Integrated Corridor Management

From the USDOT, Intelligent Transportation Systems Joint Program Office: Transportation corridors often contain underutilized capacity in the form of parallel roadways, single-occupant vehicles, and transit services that could be better leveraged to improve person throughput and reduce congestion. Facilities and services on a corridor are often independently operated, and efforts to date to reduce congestion have focused on the optimization of the performance of individual assets.

The vision of Integrated Corridor Management (ICM) is that transportation networks will realize significant improvements in the efficient movement of people and goods through institutional collaboration and aggressive, proactive integration of existing infrastructure along major corridors. Through an ICM approach, transportation professionals manage the corridor as a multimodal system and make operational decisions for the benefit of the corridor as a whole.

ICM by its nature involves multiple transportation systems, jurisdictions, and areas of responsibility, and technical or operational improvements are therefore possible only in collaboration with institutional partners and other stakeholders.

Intelligent Transportation Systems

Intelligent Transportation Systems (ITS) technologies advance transportation safety and mobility and enhance productivity by integrating advanced communications technologies into transportation infrastructure and into vehicles. ITS encompasses a broad range of wireless and traditional communications-based information and electronic technologies.

To help achieve its new multi-modal, multi-agency collaborative vision, Caltrans looks at all opportunities to move people and goods within transportation corridors in the most efficient and safest manner possible, to ensure the greatest potential gains in operational performance across all available transportation systems. This includes seeking ways to improve how freeways, arterials, transit, and parking systems, bicycle and pedestrian facilities work together. Travel demand management strategies and agency collaboration are also actively considered.

US DOT Training

The US Department of Transportation offers a variety of resources for transportation professionals. The Intelligent Transportation Systems Joint Program Office (ITS JPO) provides in-person and web-based courses and webinars on a range of ITS topics including ICM. Many of their seminars and courses are archived in addition to publishing research and guidance on ITS advances. Visit the ITS Professional Capacity Building Program for more information.

The Federal Highway Administration also provides guidance, case studies, and training on TSMO. Several of their web-based information sessions may be of interest to transportation professionals and can be accessed from the link above.

Consortium for ITS Training and Education

The Consortium for ITS Training and Education (CITE) is a unique organization of university and industry partners focused on providing comprehensive advanced transportation training and education. CITE develops interactive online courses for current professionals and college students. Training courses for continuing education units (CEUs) are available directly through CITE. The consortium offers independent online courses (for a fee and free) in areas of information technology, traffic engineering, project management, systems engineering, ITS technology and Transportation Systems Management and Operations (TSMO). They also offer certificate programs, blended courses (online and conference calls with instructor) and full semester-long courses. More information about current instructional opportunities can be found on CITE's website.

Technology Transfer Program

The Technology Transfer (TechTransfer) Program is a division of the Institute of Transportation Studies at the University of California, Berkeley. The TechTransfer Program provides training, workshops, conferences, technical assistance and information resources in the transportation-related areas of planning and policy, traffic engineering, project development, infrastructure design and maintenance, safety, environmental issues, complete streets, multimodal transportation, railroad, aviation. Trainings and workshops are held throughout the state and online and many currently available through Caltrans. Visit their course catalog and current calendar.

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Developing Stakeholder Agreements

An important aspect of stakeholder engagement is developing written agreements that express participants' interest, support, and commitment to the project. Types of agreements can include:

  • Resolution of Support - A resolution expresses general interest and support for the project without specifying any further commitment or involvement on the part of the agency. For example, the ICM team may request and receive a Resolution of Support (PDF) from the local Council of Governments (COG).
  • Project Charter - The Project Charter describes the initial stakeholder agreement and responsibilities. While not a legally binding document, stakeholders sign the Charter to express their commitment to the project.
  • Cooperative Agreement and/or Memorandum of Understanding (MOU) - These documents are legally binding and take more time to draft, review, and execute. They often require review by the agency's legal advisor. The MOU for the I-80 ICM project (PDF) illustrates this type of agreement.

In addition to specific agreements, stakeholders also contribute to the other project documents such as:

  • Letters of Support for funding applications - Stakeholders support can be vital in securing funding.

Develop Vision, Goals, and Objectives

Developing a vision and goals is an important step for any project. In addition to being required for numerous types of funding, a clear vision, goals, and objectives will provide a framework for stakeholders and partner agencies to rally around.

As the project progresses, the goals and objectives may change and become more refined. It is important to involve stakeholders in those changes to ensure consensus is maintained. The project's vision, goals, and objectives should be included in the project management pain, Concept of Operations, any stakeholder agreements including project charters and MOUs, grant applications, and stakeholder and media material as necessary.

Develop Systems Engineering Documents

As part of the ICM planning process, a number of critical systems engineering documents are required to be created and maintained.

One of the major milestones in planning an ICM system is developing a Concept of Operations (ConOps) document. A ConOps, according to the U.S. Department of Transportation, provides a high-level description of the "who, what, when, where, why, and how" of an ICM system.

A ConOps document is used to outline ICM goals such as:

  • Improve operational situational awareness
  • Promote collaboration among corridor stakeholders
  • Improve incident response
  • Improve travel reliability
  • Improve overall corridor mobility
  • Empower travelers to make informed travel decisions
  • Facilitate multi-modal movements across the region
  • Promote transportation sustainability by reducing impacts on the environment
  • Improve corridor safety
  • Reduce congestion and improve mobility, travel-time reliability, safety, and system efficiency in the corridor
  • Make better use of existing capacities across all transportation modes (car, bus, train, bicycle, pedestrian, etc.) to increase the throughput of vehicles, people, and goods with minimal or no new infrastructure
  • Bring together corridor stakeholders to create an environment for mutual cooperation, including sharing knowledge, developing working pilots, and researching and resolving key issues
  • Improve the availability and quality of data on travel conditions in the corridor to better understand corridor behavior and improve performance
  • Provide corridor users with timely, accurate information so they can make informed choices about when, how, and by what route to travel
  • Equip traffic managers and first responders with the information and tools to make real-time decisions and quickly improve traffic flow along the corridor
  • Foster positive, collaborative, ongoing corridor management practices
  • Evaluate program effectiveness to help future ICM implementations in the state and across the country

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Systems Engineering Process

Follow the Systems Engineering Framework and Documentation

Systems engineering is a structured, interdisciplinary development process for planning, designing, implementing, managing, operating, and retiring a system. This approach, as outlined in the Federal Highway Administration's Systems Engineering Guidebook for ITS, emphasized defining customer needs and required functionality early in the development cycle, before moving on to design, build, and deploy the system. The purpose is to plan for the entire life cycle of a project up-front, to minimize the risk to budget, scope, and schedule.

As a comprehensive planning approach, systems engineering relies heavily on traceability and documentation, as well as on the use of "decision gates" to determine when to pass from one step in the process to the next. Its overall trajectory is often represented by the "V" diagram:

"v" diagram

The left side of the diagram focusing on the definition and decomposition of the system to be built, the base of the building of the system components, and the right side on the integration and testing of system components, as well as acceptance and operation of the system. There are significant interactions between the two sides of the diagram: verification and validation plans developed during the decomposition of the system on the left side of the process are used on the right side to make sure the resulting components and integrated system meet the needs and requirements of the stakeholders. Throughout the process, "decision gates" are used as decision points to determine if a particular step has been completed to the satisfaction of the initially established criteria.

Systems Engineering Documentation

Document Purpose

Project Management Plan (PMP)

Primary planning document for the project, covering all phases from initiation through planning, execution, and closure. Describes what the project is to achieve; how and by whom; and how it will be reported, measured, and communicated.

Project Timeline

Overview of project schedule and milestones.

Corridor Description and System Inventory

Description of the corridor's transportation systems, management assets, and current operational status.

Systems Engineering Management Plan (SEMP)

Defines the framework for carrying out the technical tasks of the project and the systems engineering processes to be used, including plans to manage system and software development, integration, testing, validation, and deployment. Meant to be a living document, updated as the project progresses.

Concept of Operations (ConOps)

The vision and rationale for the proposed ICM system on I-210. Describes corridor operations, system stakeholders, user needs, system concept for improving corridor performance, operational scenarios illustrating what the system will do.

System Requirements

Describes what the system must do in terms of function and performance. Maps system requirements to user needs. Forms the basis for the design/build phases.

Design Documents

Contain design details for building specific components.

System Test/Acceptance Plan

Describes steps/information required for testing functional accuracy and robustness of sub-systems and overall system. Iteratively updated as development proceeds.

 

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Corridor Analysis & Inventory

Freeways & Arterials
An ICM project requires sufficient modal capacity for demand to be managed and/or shifted to alternative routes and modes when necessary. Freeways and arterials included in an ICM should have:


Freeways
Three to four travel lanes in each direction. It is preferred that at least one lane be designated as a high-occupancy vehicle (HOV) lane during peak hours or 24 hours per day, or a high-occupancy toll (HOT) lane, with shoulders and metered ramps on all or a portion of the freeway. The freeway should be instrumented and have data available (such as Caltrans Performance Measurement System (PeMS) or mobile probe data). The freeway will have recurrent, severe congestion and bottlenecks due to commute traffic as well as non-recurrent traffic due to incidents or events.

Arterials
One or two somewhat arterial networks with at least two travel lanes in each direction on either side of the freeway with no on-street parking. It is best if the arterials are instrumented, and intersections signalized.

Transportation Management Centers
According to the USDOT, FHWA, Freeway Management Program, the Transportation Management Center (TMC) is the hub or nerve center of most freeway and many large local agency management systems. A TMC, among many other tasks, houses data collected from roadway ITS, processes and fuses it with other available operational and control data, synthesizes it to produce "information", and distributes it internally and with stakeholders such as control agencies, and the traveling public. TMC staff uses information to monitor the operation of the freeway and arterials and to initiate command and control strategies to affect changes in the operation of the freeway network. A TMC is also the focus for agencies to coordinate responses to planned and unplanned events that impact traffic.

The role of a TMC often goes beyond the freeway network and/or one particular responsible agency, functioning as the key technical and institutional hub to bring together the various jurisdictions, modal interests, and service providers to focus on the common goal of optimizing the performance of the entire surface transportation system. Because of its critical role in the successful operation of a freeway management system (and perhaps the broader surface transportation network), it is essential that the TMC be planned for, designed, commissioned and maintained to allow operators and other practitioners to control and manage the functional elements of the transportation network.

Traffic Monitoring
Traffic monitoring systems are important to evaluate traffic conditions during all phases of the project including pre, post and during ICM deployment. Traffic monitoring systems may include:
  • Freeway traffic detectors- mainline, on/off-ramp, HOV
  • Arterial traffic detectors
  • Closed-circuit television (CCTV) cameras
  • Traffic signal systems
  • Data/information provided by 3rd party contractors
  • Transit, rail, and bus monitoring systems

If a section of the corridor lacks sufficient traffic monitoring systems, funding should be identified and allocated as early as possible to support necessary new or improved systems to ensure adequate coverage of all freeways and major arterials within the corridor. Obtaining third-party probe data should also be considered to supplement existing systems.

Improving and maintaining traffic monitoring system health for the entire corridor must also be a priority as they provide the information and command and control tolls necessary to plan for, implement and conduct ICM.

Data Collection

illustration of how a fully developed ICM system could work

 

The figure above from the I-210 Pilot Concept of Operations document is an illustration of how a fully developed ICM system could work. The large blue box at the bottom of the diagram represents the transportation corridor being managed. Within the box, the seven smaller blue boxes show the various transportation system elements. Improving system operations begins with the need to collect comprehensive and reliable information about how individual elements are operating. This is illustrated by the gray boxes representing various data streams from the Transportation Corridor into the Data Collection/Validation/Fusion box. This need includes collecting information from traffic sensors, control devices, probe vehicles, transit monitoring systems, parking monitoring systems, and user-generated data through mobile applications and social networks on a 24-hour/7-day-a-week basis. Information about active incidents, weather, construction and maintenance schedules, and other planned events may also be collected. All collected data must further be validated prior to being used to ensure that no erroneous information is used in system evaluations. Data processing may also involve the application of data fusion algorithms designed to address potential discrepancies among data collected from various sources and gaps in collected data.

The following lists identify the types of data that have been identified as critical for supporting the operation of an ICM system:

Characterization of traffic conditions on I-210 and other considered freeways

  • Traffic volumes, speeds, and density on mainline and HOV traffic lanes
  • Traffic volumes on both on-ramps and off-ramps
  • Actual travel times along freeway segments

Characterization of traffic conditions on corridor arterials

  • Traffic volumes from key intersection approach
  • Proportion of vehicles turning left, going through and turning right at key intersections
  • Queue length estimates for key intersection approaches
  • Average traffic speed between intersections along arterials of interest
  • Actual travel times between intersections along arterials of interest

Characterization of parking availability

  • Occupancy of park-and-ride facilities linked to the ICM system

Characterization of transit operations

  • Frequency of passage of transit vehicles along relevant transit routes
  • Average occupancy of transit vehicles operating along each relevant transit routes
  • Active service deviations

Status of devices used to monitor traffic

  • Health status of loop detectors, video detection systems, Bluetooth devices and any other types of monitoring devices used to collect traffic data

Status of traffic control devices

  • Active metering rate at each freeway on-ramp
  • Signal timing plan in operation at each intersection
  • Health status of traffic signal control equipment

Status of informational devices

  • Message currently displayed on freeway changeable message signs (CMS)
  • Message currently displayed on arterial trailblazer signs or CMS
  • Messages being pushed or recently provided to the regional 511 system and third-party information providers
  • Health status of freeway CMS
  • Health status of arterial CMS or trailblazer signs

ICM system status

  • Information indicating whether the ICM system is currently idle
  • Health status of various ICM system components

Information characterizing the status of devices used to support ICM operations further needs to be available on an on-demand basis. For instance, information indicating which signal timing plans are currently being run at given intersections or the active ramp metering rate on given freeway on-ramps must be available when the ICM system needs the information to assess corridor operations or develop response plans. In many cases, information availability is facilitated by systems monitoring devices on a real-time basis, such as traffic signal control systems monitoring signal indications every second or compiling signal operational statistics on a cycle-by-cycle basis. Where such monitoring capability does not exist, appropriate remedial actions will need to be considered.

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Transit

Incorporating transit information allows for an even greater number of technologies, resources and strategies to be considered and implemented within the corridor. Transit offers additional capacity within the corridor and can assist with overall demand management. Where possible, rail and bus information should be incorporated, including real-time status, vehicle volumes and ridership data and transit related strategies implemented in the corridor such as transit signal prioritization/preemption.

ICM transit strategies include:

  • Adjusting transit capacity during special events and/or lengthy incidents or based on anticipated demand
  • Implementing transit-only lanes along select arterials and/or at select intersections
  • Providing dynamic connection protection at key transit transfer points

Active Transportation and Micromobility

Incorporating active transportation information (pedestrian and bicycle) and micromobility information (small, low-speed, human- or electric-powered transportation device, including bicycles, scooters, electric-assist bicycles, electrical scooters (e-scooters), and other small, lightweight, wheeled conveyances) assists in creating a more complete estimate of corridor mobility. Inclusion of such data also allows consideration of a host of additional management strategies and estimation of potential roadway and transit strategies on travelers not using transit or autos.

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Parking

Parking availability and information, from both publicly and privately operated facilities, should be incorporated into an ICM program whenever possible. Park and ride information can be provided to encourage drivers to park and take transit or possibly walk to their destination. A lack of parking may be an impediment to the promotion of transit alternatives or transit use in general.

 

Depending on real-time parking information availability, multiple situations may occur a) drivers arrive at a station only to find no parking and then decide to drive (or park illegally and face a fine) b) drivers may travel further than necessary to a station they know does not regularly fill up and c) drivers may skip transit altogether to avoid the hassle. All of these situations result in more vehicles on the road and could be substantially reduced by real-time parking information programs.

Traveler Information

Traveler information systems are used to communicate current travel conditions, suggest alternate routes, and encourage mode shift. Traveler information systems include:
  • CMS
  • Highway advisory radios (HARs)
  • Bus/train tracking information systems
  • 511 traveler information services
  • Personalized traveler information applications and services
  • Offline navigation applications
  • Connected mobile navigation applications such as Waze and Apple Maps

Enhancing information dissemination may enable travelers to make informed decisions that may lead to a more efficient distribution of trips across time and modes. While travelers often make decisions based on their experience, they do not always have comprehensive or accurate knowledge of the alternative travel options that are available to them. As a result, travelers often reject alternative travel options based on inaccurately perceived difficulties. In this case, more information would help alleviate these challenges.

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Integration With Other Systems

Enabling communication so the ICM system can receive data and send response plans is an essential component of ICM. This will most likely require integrating multiple systems used by project stakeholders. Types of systems that should be considered for integration include:

  • Ramp Metering Systems
  • Traffic Signal Systems
  • Arterial and Freeway Sensor Data Systems
  • Changeable and Dynamic Message Sign Systems
  • CCTV Systems
  • HARs
  • Parking Information Systems
  • Transit Information Systems
  • Information Exchange Networks

Systems should be reviewed and evaluated early in the planning process as upgrades are likely to be required for proper integration.

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Corridor Criteria

Core Considerations for Selection

When considering ICM implementation, Caltrans districts should identify and select corridors that the district believes the most benefits can be gained in terms of performance improvement per the most recent Caltrans Strategic Plan Goals. District Deputies of Traffic Operations need to take full ownership of the performance improvements for corridor(s) selected for this focused effort, thereby contributing to both district and statewide performance goals and targets.

Selecting a Corridor for ICM

A number of processes can be used to select an ICM corridor including:

  • Defining selection criteria including operational and institutional criteria
  • Identifying and contacting project stakeholders
  • Working with stakeholders to identify potential corridors
  • Conducting a detailed assessment of the candidate corridor
  • Narrowing the choices and making an initial selection
  • Evaluating the assessment results against selection criteria
  • Making a “go or no-go” decision
  • Considering alternatives, if necessary

Operational Criteria

The corridor operational criteria are the physical features and modes of transportation found along a corridor. These criteria are important because certain operational characteristics are more likely to lead to positive ICM project results.

  • Corridor Length and Components – An ideal corridor is ten to twenty miles in length and linear, consisting of a freeway, parallel arterials, and transit. Entertainment venues, businesses, residences, and educational uses located adjacent to the corridor should be identified.
  • Congestion – Since reducing corridor congestion is a goal of ICM, it is key that the corridor has a high level of congestion.
  • Freeways – The freeway should include three to four travel lanes in each direction with at least one HOV lane, with metered ramps. The freeway should have sensors, mobile probe data or some other data source to monitor traffic flow.
  • Arterials – Arterial networks on either side of the freeway, with timed signals approximately one-half mile apart, at least two travel lanes in each direction, and no on-street parking, are best.
  • Bus/Rail Transit – Regional or other transit-serving bus service on the freeway operating in the HOV lanes, local bus service on the arterials, and Bus Rapid Transit or express bus service are important. Light rail transit can also be useful as it provides additional re-routing options and opportunities for mode shift. The availability of parking and park-and-ride facilities should also be considered.

The operational characteristics of a corridor have implications on the social, economic, and environmental aspects of the communities and region in which it is located. For example, a congested urban corridor can negatively impact residents’ and travelers’ quality of life if travel times are increasing, unpredictable travel times, and delays in freight delivery. Also important are the transit services and the ability for the elderly, disabled, or those who choose not to own an automobile to move through the corridor and access jobs, schools, and services.

Operational criteria includes:

  • A well-instrumented roadway (in-pavement sensors on the freeway mainline and ramps, with collected data automatically processed through the PeMS or Advanced Transportation Management System)
  • Directional traffic flow corresponding to morning and evening commute hours
  • A network of parallel arterials linked to the congested freeway
  • Existing infrastructure investments that can be leveraged
  • Extensive transit service, a network of bicycle lanes, and parking/park-and-ride facilities

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Engaging Corridor Stakeholders

In a project as multi-dimensional and collaborative as ICM, engaging stakeholders is a fundamental and ongoing activity. It is the context in which the system is planned, developed, deployed, and operated. Outreach and communications efforts and stakeholder engagement continues during the entire project and takes a variety of forms, including:

  • Contacting stakeholders
  • Enlisting participation
  • Keeping participants informed
  • Educating stakeholders about various aspects of the project
  • Holding routine/scheduled stakeholder meetings
  • Listening to and addressing concerns
  • Coordinating activities among stakeholders, including reviewing and executing agreements
  • Building relationships with stakeholders and partners
  • Publicizing the project and communicating with the public
  • Developing a common understanding and consensus for moving the project forward
  • Engaging/informing agency external affairs/communications staff and legislative partners is important to project support, implementation and success and should be strategically considered and conducted when appropriate.

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User Needs

User needs govern the development of the ICM system concept and are determined based upon a conceptual system analysis and input from the stakeholders and the system development team.

Project Management Plan

The Project Management Plan (PMP) is the primary planning document of a project. Elements captured in the PMP normally cover all phases of a project, from initiation through planning, execution, and closure. The PMP provides a comprehensive baseline of what has to be achieved by the project, how it is to be achieved, who will be involved, how it will be reported and measured, and how information will be communicated. Specific elements addressed by the PMP typically include the following:

Overview Why the project is being conducted and its primary objectives
Scope Business needs, requirements, deliverables, constraints, and work breakdown structure
Project Team The people working on the project, their roles and responsibilities
Schedules Activities schedule and project milestones
Communications Communication type, channels, and the reporting approach 
Costs
Project budget and its funding approach
Quality Control Quality measurement and control approach
Closure Closure approach, including protocols for handing-off deliverables
Changes  Procedures used to track changes in the project
Baselines Scope, schedule, and budget baselines
Project Evaluation
Methods to assess project activities and outcomes

 

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Concepts of Operations

The development of the ConOps is part of the systems engineering analysis process that the Federal Highway Administration (FHWA) requires be followed for the development of Intelligent Transportation System (ITS) projects. The development of a ConOps typically occurs after a needs assessment and some portion of a preliminary project planning have been conducted; but before a full design is initiated. In this context, the primary functions of a ConOps are to:

  • Establish the rationale for the system
  • Refine the vision, goals, and objectives of the proposed system
  • Develop representative's operational scenarios illustrating what the proposed system will do
  • Ensure that the needs and expectations of stakeholders are captured early in the system development process
  • Ensure that the system functionalities are linked to the mission, goals, and objectives of participating agencies
  • Begin the traceability of the Systems Engineering Process

A ConOps seeks more specifically to illustrate the benefits that can be obtained from the application of advanced technologies; the coordination of systems traditionally used independently to manage the movements of vehicles, persons, and goods within a corridor; and the development of cooperative operations among corridor systems and stakeholders. Only high-level descriptions are typically provided in a ConOps as this document is primarily meant to act as a discussion vehicle and consensus-building tool among potential project stakeholders.

Specific questions that the ConOps seeks to address regarding the proposed ICM system include:

  • What are the goals and objectives of the system?
  • How will the system achieve its stated goals?
  • How can corridor performance be adequately captured?
  • How will existing corridor operations be enhanced by the proposed system?
  • What new functionalities will be provided by the system?
  • Who are the system users?
  • Who are the various system stakeholders?
  • What are the stakeholders’ specific roles?
  • What are the operational and institutional environments in which the system will operate?
  • What would be the main system components and functionalities?
  • What sequences of activities will typically be performed to address specific situations or requests of interest?
  • What resources would be needed to design, build, operate, and maintain the system?
  • What operational, technical, and institutional elements may influence the design and implementation of an actual system?

While it is expected that the ConOps will inform and guide future system design activities, it must be kept in mind that it is meant to be living document, i.e., to be altered to address changes in user needs, system requirements, operating environment, desired functionalities, or constraining elements.

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Systems Engineering Management Plan

The document is typically developed early in the process as a supplement to the PMP.  While the PMP addresses general project management details, such as project scope, participating personnel, schedule of activities, task scheduling, and costs, the Systems Engineering Management Plan (SEMP) focuses on the technical plans and systems engineering activities that will be used to carry the project to its end. Its purpose is to detail the processes that will be used to support the design, implementation, integration, verification, and eventual operation of the proposed system.  Its development typically uses the foundation laid by the PMP to build the framework for implementing the technical tasks of the project.

systems engineering managment plan diagram

The SEMP does not attempt to answer what is to be done, but rather how what needs to be done should be executed.  For example, the SEMP does not seek to define what the product concept is. It asks instead how the product concept is to be determined. This distinction between “how” and “what” is important in understanding the purpose of the SEMP.  While the SEMP answers “how” questions, the various documents and processes it describes are used to answer the “what" questions.

Because the SEMP is developed early in the life cycle of a project, it is generally written with only a partial understanding of what is to be developed.  Available information typically includes only the results of preliminary corridor operational evaluations and needs assessments, as well as preliminary concept explorations that might have been conducted to assess project feasibility. As a result, several versions the SEMP may be released during a project, usually within the first half of the systems engineering process:

  • A first version is generally produced by the project management staff early in the project life cycle to define the framework within which systems engineering activities are to be conducted. At this stage, only enough detail is included to allow the identification of all needed tasks and important constraints on the execution of each task. 
  • As the project progresses through the Concept of Operations, definition of system requirements, and system design, the various sections or plans identified in the SEMP framework are gradually completed. Examples of elements that are commonly defined at this stage include details of the tools that will be used to manage the requirements, the methodology that will be used to design software components, the processes that will be used to manage system configurations, methods to be followed for verifying system components, etc.

As indicated, the SEMP is not meant to be a static document. Instead, it is meant to be a living document subject to various updates until it reaches a final, stable version.

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Analysis, Modeling, and Simulation Report

Assessing Potential Project Benefits: Analysis, Modeling, and Simulation

The data collected about a corridor can provide a broad and detailed picture of its attributes, operations, and user needs. This information then raises key questions for the ICM project:

  • How could ICM improve corridor performance?
  • What are the most important scenarios that can be addressed by the project (recurrent congestion, incidents, weather, planned events, etc.)?
  • Which arterials should be included?
  • What response strategies should be considered?
  • How should the effectiveness of response strategies be measured?
  • How should benefits and costs be assessed?

These questions are explored through analysis, modeling, and simulation (AMS)—the use of modeling and simulation tools to test the impact of various control strategies and assess the potential benefits and implications of ICM.

An Evaluation Process

AMS is an evaluation process used to understand traffic operations along a corridor, identify key transportation challenges, and explore potential management strategies to improve corridor operational performance. A vital part of the systems engineering methodology, AMS is tasked with ensuring that solutions are chosen correctly, funds are spent effectively, and performance is measured quantitatively.

Core Components

The core components of AMS are:

  1. Analysis—Developing as thorough an understanding of the corridor as possible through detailed investigation of available information about the corridor.
  2. Modeling—Developing and calibrating a model that captures existing traffic conditions. Model building is an iterative process that begins with the best data and best understood parts of the corridor and continues as additional data are analyzed and the extent of the model is expanded.
  3. Simulation—Using the developed model to improve understanding of traffic behavior on the corridor and to define and select the best management strategies and control interventions to address its key challenges.

System Requirements

The purpose of system requirements is to define what the ICM system should do. This represents a key decision point in developing the system, as the requirements set the direction for how the system will be designed, built, and ultimately implemented. The process of generating requirements must therefore make sure that stakeholders, implementers, users, and future reviewers of the system clearly understand what it must do to function effectively.

To define what the ICM system should do, it is essential to understand what is meant by the "system." Not simply a piece of technology, the system is considered a total entity made up of people, organizations, hardware, and software. All these components must work together to achieve the goals of the project, and the system requirements must specify what is expected from each.


ICM system component diagram 

Defining what is required of each component is a challenging task, because no single person understands the system fully when requirements-gathering begins. Nor can they, for the requirements emerge from the additive process of each person defining what they believe the system must do in order to meet their agency's particular needs.

In a successful requirements-gathering process, each participant will learn more about their fellow users and how their requirements can fit in with the requirements of others. This process is iterative and can require creativity and compromise. It is thus both educational and definitional:

  • To educate stakeholders about the range of needs along the corridor
  • To define how those needs can be met to benefit corridor operations as a whole

Sources of Information

For ICM, requirements are based primarily on information gathered from system stakeholders on the purpose and desired functionalities of the system, supplemented by additional criteria, guidelines, and technical expertise. Sources of information include:

  1. User Needs gathered from local partners and stakeholders
  2. The Concept of Operations developed based on the identified user needs
  3. Comments gathered from interviews with individuals and meetings focused on requirements-gathering
  4. Transportation Systems Management and Operations (TSM&O) success criteria
  5. ICM Capability Maturity Matrix (CMM) developed by Caltrans
  6. Review of system requirements developed for existing ICM systems across the U.S.
  7. Review of various technical documents, websites, and presentations related to ICM
  8. Advice provided by informed personnel from other U.S. ICM sites
  9. Advice from knowledgeable consultants
  10. Management judgment

Challenges

Defining the breadth and depth of the requirements.

  • Breadth – The project team should understand that requirements include people, organizations, software, and hardware; all facets of the ICM CMM. This is in contrast to the view that requirements should focus mainly on software. Many of the requirements are based on an assumption that the largest challenges of ICM are not in the software but in the successful integration of people and processes to create and manage a real-time operational system. Many essential requirements would be missed if only requirements for software elements were included.
  • Depth – Requirements should be specified to the level that identifies and resolves significant differences in stakeholder opinion and/or beliefs, particularly before design of the proposed system is initiated, where it would be preferable not to discover fundamental differences between stakeholders. One of the purposes of requirements-gathering is to ensure that the project team has educated personnel on ICM and arrives at real agreement. This requires in-depth discussions on who or what will perform each function.

Defining the difference between a requirement, a design constraint, and a design decision-a traditional answer is that requirements define what the system must do to meet the user needs, design constraints limit the possible implementation methods, and design decisions determine how to implement the requirements. In practice, it can be difficult to distinguish between a low-level requirement, a design constraint, and a high-level design decision. By its definition, a requirement is something that a person believes is required for the system to function correctly. One person’s beliefs are frequently different from another’s and often related to how a function will be implemented. The following rule may be applied: If a specific item that could reasonably be considered a design decision was mentioned by more than one person, this item can then be listed as a potential requirement.

For areas where requirements are missing, the following actions may be taken:

  • If, when looking across the process flows discussed in the user meetings, a missing piece is identified that was at the same level as other requirements, it could be included as a requirement.
  • If a requirement is at such a high-level that it is unclear how or whom to ask to implement, then it may be broken down into smaller requirements.
  • As source material from different areas are reviewed it may be discovered that certain items were omitted from partner discussions and interviews. In such cases, professional judgment is necessary to determine whether to add a requirement or not.

Unfamiliarity with the ICM concept - The concept of ICM is new to many people who will be asked to provide requirements. As such, they will look to the management team to help define the requirements. The management team, including the contractor, should use their professional expertise combined with knowledge gained from previous efforts and the input from experts wherever available to assist in guiding the project.

Categories of Requirements

As illustrated in the following diagram, requirements may be organized into categories that match the major functions in the corridor management workflow:


connected cooridors requirements chart

 

The main categories shown above in blue support these workflow functions:

Institutional Support People and organizations work together to manage, resource, fund, and maintain a working ICM system that is accepted by all stakeholders
Strategic Incident Response Planning Stakeholders routinely plan, review, and update responses to incidents
Corridor Monitoring Real-time corridor status information is continually monitored
Real-time Response Planning Predefined response plan components and the current corridor state suggest tailored response plans
Response Plan Implementation Once a response plan is chosen, it will then be implemented by corridor resources

 

To learn more about user needs, themes, actors and stories, and the categories of requirements, please visit the System Requirements section on the Caltrans ICM website.

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High-Level Design

The high-level design process results in the development of a document that identifies the primary subsystems and major components of the proposed ICM System. The document also explains the selection, development and integration of these components into a system that satisfies the system requirements as defined previously in the Systems Requirements Document.

The high-level design and detailed design steps are part of the System Definition and Design phase in the systems engineering process. The resulting high-level design elements are in turn used to inform and guide the more detailed design of the various system and subsystem components.

The high-level design below illustrates the various system components that may be included in an ICM including the field elements (green), data hub (red), the Decision Support System (blue), and the Corridor Management System (purple). An example of a high-level design document is available on the UC Berkeley Connected Corridors website. 

high level design process chart

 

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Headquarters Funding

Programmatic funding provided by the Caltrans Traffic Operations Program for ongoing support of ICM has not been identified. All ongoing operations costs, contractor, and employee related support costs must be carefully estimated, and resources identified.

District Funding

Outside Funding

General

Initial research will need to be conducted to determine whether federal, state, regional, and/or local funds are available for ICM projects in the corridor area. General approaches include:

Approach Description
Identify and monitor state and federal funding sources Discussions with Caltrans and FHWA experts to identify state and federal funding through grants and awards, and through both public and private sector sources. A spreadsheet should be prepared to document potential funding possibilities, awards, and grants and updated when necessary.
Identify and monitor regional and local funding The same process outlined above should be followed, except at the regional and local level, including local transportation sales tax measures and pass-throughs from state and/or regional agencies.
Identify and monitor sources of Caltrans funds Caltrans Programs provide resources for ongoing operational support and upgrade of existing systems, while Caltrans Districts also have the ability to pay for certain items, many potentially included as part of the State Highway Operations and Protection Program (SHOPP) requests. It is incumbent on the ICM project team to identify necessary and available resources from all Caltrans' sources.
Investigate grants Grants may be available from the Federal Highway Administration (or agencies under the FHWA), United States Department of Transportation (DOT), through postings in the Federal Register, and/or through California Grants.
Consider awards

There are various awards in specific categories for transportation projects. While these awards to not necessarily provide funding, they can be advantageous for the project by raising its visibility and recognizing its value. Awards include, but are not limited to:

  • American Association of State and Highway Transportation Officials (AASHTO) Alfred E. Johnson Achievement Award (engineering and management)
  • American Public Transportation Association (APTA) State Distinguished Service Award
  • American Society of Civil Engineers Francis C. Turner Award (transportation engineering)
  • California Sustainability Alliance's Sustainable Showcase Awards
  • Institute for Local Government Beacon Awards (climate change)
  • Institute of Transportation Engineers Transportation Achievement Award
  • LA Metro/Orange County Transportation Authority (OCTA)/Ventura County Transportation Commission (VCTC) Diamond Awards (regional transportation)
  • Transportation Research Forum's Herbert O. Whitten Service Award (transportation)
  • various Transportation Research Board (TRB) awards
Research transportation sales tax measures In California, 20 counties have transportation sales tax measures.

 

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Local Funds

Local funds may be available from existing or expanded budgets, for Operations and Maintenance, or from "return to source" funds from regional sales tax measures (for example). Local agency partners should be encouraged to provide local funds in addition to providing staff time and other resources.

Regional Funding

  • Funding for the arterial improvements is the responsibility of the local jurisdictions and transit agencies, either individually, or as a group. Funding may come from a variety of local, state, and federal sources such as Proposition funds, Regional Improvement Funds, and Congestion Mitigation and Air Quality Improvement Program funds.
  • Transportation Sales Tax Measures - In California, 20 counties have transportation sales tax measures.

Federal Funding

As with state sources, the programs, project types, criteria, etc. change year to year. There are several websites that can be searched for information:

The Fixing America's Surface Transportation (FAST) Act established the Advanced Transportation and Congestion Management Technologies Deployment Program (ATCMTD) to make competitive grants available for large scale installation and operation of advanced transportation technologies to improve safety, efficiency, system performance, and infrastructure return on investment. The Program is currently authorized through 2020 for $60 million per year. Eligible activities include:

  • advanced traveler information systems
  • advanced transportation management technologies
  • infrastructure maintenance, monitoring, and condition assessment
  • advanced public transportation systems
  • transportation system performance data collection, analysis, and dissemination systems
  • advanced safety systems, including vehicle-to-vehicle and vehicle-to-infrastructure communications
  • technologies associated with autonomous vehicles, and other collision avoidance technologies, including systems using cellular technology
  • integration of intelligent transportation systems with the Smart Grid and other energy distribution and charging systems
  • electronic pricing and payment systems or
  • advanced mobility and access technologies, such as dynamic ridesharing and information systems to support human services for elderly and disabled individuals. [23U.S.C. 503(c)(4)(E)]

The Program will cover up to 50% of the project cost and matching funds must be considered before applying. The application is due at the beginning of June each year. More information is available on the FHWA's Grants Program webpage.

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Strategic Management Plan

ICM is a collaborative effort to improve overall mobility and safety within the corridor by managing travel conditions during incidents and events having a significant impact on travel. Expected benefits of ICM include improved travel time reliability, reduction in delay, reduced incident response times, reductions in secondary incidents, and improved coordination between stakeholders. ICM is also related to other Caltrans efforts.

Statewide Planning for Operations

 Planning for Operations is a concept to promote multimodal planning that supports transportation system management and operations. System management strategies typically have high benefit/cost ratios and help Caltrans achieve its goals of system performance, stewardship, safety, and operational efficiency. New and evolving federal and state policies direct Caltrans to improve its system management planning practices as a basis for performance-based decision-making. Intelligent Transportation Systems (ITS) planning and deployment is an important component of Planning for Operations activities.

Capability Maturity Model Framework

The Capability Maturity Model (CMM) Framework is intended to improve the effectiveness of Transportation System Management and Operations (TSMO) applications and activities by assisting staff and management who are central players in statewide and regional TSMO agencies to understand all dimensions of TSMO and identify deficiencies. The CMM framework provides a structured focus on the six dimensions of capability, together with a facilitated self-assessment process or workshop at which participants evaluate their current TSMO-related activities using criteria from the CMM framework that define capability levels. The current challenges and low capability levels identified by workshop participants are used to identify actions needed to improve capability and are subsequently embodied in an implementation plan to improve an agency's ability to implement TSMO.

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Transportation System Management and Operations

Caltrans has embarked on the development of a comprehensive program to further California's TSMO capabilities. TSMO offers the potential to provide an integrated program to optimize the performance of existing infrastructure through the implementation of specific systems and services that preserve capacity and improve reliability and safety.

Caltrans has hosted TSMO Regional Operations Forums throughout the State with Caltrans Districts and local agencies to identify specific corridors where TSMO activities such as incident management, traffic signal timing, ramp metering, road weather management, and others could potentially improve transportation network performance.

Transportation System Management and Operations Pyramid

In the early 2000's, Caltrans established a mobility model with a foundation in maintenance and management of our existing transportation system. Efforts over time have evolved and continue to reinforce that transportation investments have more impact if built upon the philosophy embodied by our TSMO pyramid.

The base of the pyramid is system monitoring and evaluation where system performance is determined. The next level is smart land use/demand management which focus on aligning travel demand and transportation system capacity. The next level includes intelligent transportation systems (traffic signals, ramp meters, changeable message signs, etc.) that are used for monitoring and control to increase the efficient use of the transportation network. The next level includes operational improvements taken to also improve the efficient use of the transportation network. The final level, taken after all other actions have been taken, is system completion and expansion.

 

Transportation System Management and Operations Pyramid

 

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Institutional Needs

Institutional needs or requirements generally focus on strategic planning and on the organizations and people needed to execute those plans. They focus on how people and organizations are structured, funded, motivated, and informed. These requirements are based on the premise that active collaboration among people and organizations is the cornerstone on which an ICM effort is built. Stakeholders and expert frequently identify institutional requirements as the requirements most affecting the success of an ICM effort, which is why they are listed first. They include:

  • Maintaining and executing a corridor strategic plan for data collection, corridor control, and performance metric calculation
  • Ensuring that assets defined in the strategic plan are in existence
  • Maintaining project champions
  • Defining and implementing a solid management infrastructure, associated business processes, and corresponding knowledge, skills, and abilities (KSAs)
  • Ensuring all stakeholders are included and engaged in corridor decision-making and that these decisions are made within a culture of trust and communication
  • Ensuring required resources are committed to corridor day-to-day operations
  • Providing a properly skilled, educated, organized, trained, and motivated work force
  • Establishing and maintaining communications channels with all stakeholders and agencies throughout the life of the I-210 Pilot
  • Locating, securing, and monitoring funding opportunities
  • Ensuring sufficient funding is available for day-to-day operations
  • Managing Memoranda of Understanding and other agreements with stakeholders, organizations, agencies, and/or private companies and ensuring that they remain updated

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Caltrans Internal Changes for Corridor Management

A Caltrans project, Organizing for Corridor Operations, was conducted to identify institutional challenges related to ICM implementation. The project had six key deliverables: Corridor Management Work Plan, Corridor Performance Monitoring and Evaluation Work Plan, Corridor Performance Report Template, Statewide Planning for Operations - Recommended Updates to Planning and Guidance Document, Inventory of KSAs and Technical Assistance, and a Training Plan. The goal was to help Caltrans align the Division of Traffic Operations, especially in ICM pilot districts, with the principles of system management to maximize the performance of the existing and future transportation system. The project developed several optional organizational charts which were presented to District management and revised to ultimately lead to a more detailed, preferred option.

The consultants developed four organizational options that were vetted with executive management, Operations Office Chiefs, Senior Operations staff, and the Strategic ICM Pilot Team. Ultimately, Option 4 was selected as the preferred option by staff at all levels. The preferred option builds from prior reorganization work done in the Caltrans districts of Traffic Operations to organize geographically and to assign staff to a new Corridor Manage position. The new organization provides for clear lines of reporting and supervision. The option is also scalable and can be deployed in small, manageable steps, a few corridors at a time. The option provides a logical path to the complete transition to a corridor management organizational structure.

 

corridor managment organizational chart

 

The option above was chosen because it most fully supports the move to a model that focuses on corridor and system management, and other Caltrans priorities. In addition to the recommended reorganization structure, an Implementation Plan was developed in coordination with District management and includes the following categories of activities:

  • Program Administration
  • Staff Recruitment and Template Development
  • Training and Staff Assignments

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Performance Metrics

Minimum ICM performance measures should be identified in the following areas:

  • Mobility: Better people and freight movement
  • Reliability: More predictable corridor travel times
  • Safety: Fewer collisions, injuries, and fatalities; and less severity
  • Productivity: Fewer bottlenecks or hotspots that reduce flow rates
  • Emissions and Fuel Consumption: Reduced greenhouse gas emissions

The ability of the ICM system to produce corridor improvements satisfying all stakeholders depends on measuring project impacts using metrics to assess corridor operations. The selection of such metrics is a somewhat complex process, as different metrics are often used to manage freeways, arterial networks, transit systems, urban mobility, and environmental impacts. As an example, the table below lists metrics commonly used to evaluate specific operational dimensions of freeways, arterials, transit, and parking systems.

Ideally, a limited set of metrics should be used to evaluate different aspects of corridor operations. This will not only simplify data processing needs, but also facilitate the understanding of the decisions made by the ICM system. From this perspective, based on corridor stakeholder input and experiences gathered from other ICM implementations, the following base metrics are suggested for evaluating corridor performance:

Potential Corridor Metrics

Metric Freeway Operations Arterial Operations Transit Operations Parking Operations
Mobility
 Average travel time  
 Average travel speed  
 Vehicle-hours of delay (VHD)  
 Person-hours of delay (PHD)  
 Average delay per vehicle
 
 Average delay per person  
 Congested lane-miles    
 Level of Service (LOS)    
 Productivity
 Vehicle Flow  
 Vehicle-miles traveled (VMT) ●   
 Vehicle--hours of travel (VHT) ●   
 Person flow ●   
 Person-miles traveled (PMT) ●   
 Person-hours of travel (PHT) ●   
 Flow density    
 Queue length    
 Saturation flow rate    
 Vehicle flow capacity ○   
 Person flow capacity ●   
 Volume-to-capacity ratio    
 Number of transit boarding/alighting     ●   
 Parking availability      
 Parking utilization rate      
 Reliability
 Travel time index  
 Buffer index  
 Mean time travel  
 Median time travel  
 Nth percentile travel time  
 On-time performance      
 Safety
 Number of accidents
 Number of accidents with fatalities
 Number of accidents with injuries
 Frequency of accidents (per time periods)
 Frequency of accidents with fatalities
 Frequency of accidents with injuries
 Rate of accidents (per million VMT)  ○
 Rate of accidents with fatalities  ○
 Rate of accidents with injuries  ○
 Environment
 Fuel consumption per vehicle  
 Fuel consumption per person  
 Emissions per vehicle  
 Emissions per person  
 ● Measure of primary interest  ○ Measure of secondary interest

 

  • Change in person-miles traveled (both on a nominal and percentage basis) to measure change in overall travel demand placed on the corridor when considering both roadways and transit services
  • Change in person-hours of delay (both on a nominal and percentage basis) to measure improvement in corridor mobility
  • Change in travel time reliability to measure potential reduction in uncertainties associated with highly variable traffic conditions
  • Reduction in the number and severity of secondary collisions (both on a nominal and percentage basis) to measure the safety benefits of the implemented corridor management strategies

As indicated, using person-based metrics allows considering both increase/reduction in motorized traffic and increase/decrease in transit ridership, thus overall changes in travel demand. However, a potential problem with the use of person-based metrics is to know how many individuals are present in each vehicle (vehicle occupancy). While information about the number of occupants in each vehicle is typically unavailable, average values may be used for passenger cars and for transit operations based on historical data from relevant occupancy surveys. While using such values would not allow developing an exact operational assessment, no existing technology currently allows such an assessment to be made. While imperfect, using average vehicle occupancy thus provide a practical approach to consider the relative carrying capacity of passenger cars and transit vehicles in the current evaluation context. Vehicle-based evaluations would nevertheless remain possible by attributing the same occupancy value (i.e., a value of 1) to all vehicle types.

Whether additional metrics should be used and how many metrics should be combined to determine recommended response plans is determined collectively by corridor stakeholders during the design phase of the ICM system.

FHWA Performance Measure Targets from the ICMS Concept of Operations for a Generic Corridor

Average travel time per trip for the corridor and each network (includes long and short trips)

Corridor: 20 mins                Arterials: 25 mins

Freeway: 15 mins               Rail: 20 mins

Freeway HOV: 10 mins      Bus: 25 mins

Average delay per trip for the corridor and each network

Corridor: 10 mins                Rail: 5 mins

Freeway: 5 mins                 Bus: 8 mins

Arterials: 7 mins

Travel time index Corridor daily vs. off peak: 1.2     Freeway daily vs. off peak: 1.1

Corridor incident vs. peak: 1.3     Freeway incident vs. peak: 1.4

Arterials daily vs. off peak: 1.3     Rail daily vs. off peak: 1.0

Arterials incident vs. peak: 1.4     Rail incident vs. peak: 1.4

Bus daily vs. off peak: 1.2

Bus arterial incident vs. peak: 1.4

Buffer index Corridor wide buffer index of 30%
Average parking availability per facility per time-of-day Zero average availability at end of peak period only 90% of the time
Customer satisfaction as obtained from traveler surveys 80% overall satisfaction with corridor

80% satisfaction with corridor traveler information and accuracy

 

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Corridor Model and Traffic Simulation

Model building is an iterative process that begins with the best data and best understood parts of the corridor and continues as additional data are analyzed and the model is expanded.

The overall model-building process is illustrated in this figure:

overall model-building process diagram

As the figure shows:

  • Information about the corridor comes from various sources and different years and needs to be checked in a pre-processing step. Does it look reasonable (i.e., not garbled or fragmentary)? Is it fairly consistent? Does it seem usable for the intended purpose?
  • After the initial checks, the data is processed to produce the information needed for modeling and simulation, including:

illustration of informaiton needed for modeling and simulation, including travel times, network geometry, speed limits, signal timing, flows, and turning ratios.

  • Processed data is used to construct the model, a portion to calibrate the model, and a portion to validate the model's simulation results against observed traffic conditions.
  • The completed model can be used to simulate traffic conditions along the corridor under various operational conditions, such as no incident, an incident with no intervention, and an incident with intervention.

The five primary purposes of the model are:

Pre-planning To inform and validate the process of building incident response plans
Real-time To score a response plan for use by the Decision Support System when the Pilot is deployed
Retrospective To improve response plans and prediction capabilities and post-incident evaluations
Special planning To inform other special planning needs
Outreach and stakeholder support To visually demonstrate progress and build confidence

 

A micro-simulation model is vital to any ICM project. The biggest limitation with model development is the available data, particularly data that can be used to determine flow patterns along arterials, such as where trips originate, which routes are taken, etc. New sensors will help fill critical gaps and the ISM team continues to work with stakeholders to ensure that all available existing sensors are functioning properly. Every bit of data helps and improves the reliability of the model.

The model is used to simulate traffic conditions and the results are compared with data from the field to determine its accuracy. Incidents and response plans are simulated to determine how a candidate action may affect traffic conditions. The model and the predicted outcomes of the response plans are currently being evaluated in close partnership with the stakeholders.

Corridor Re-Routes

Very early on in an ICM Pilot, the project team began designing corridor-wide response plans for incidents. What should a response plan do? What ITS infrastructure is needed to implement the response plans? How and when are decisions - in real time - which response plan to use? What approval mechanisms are needed and how do we know when to end a response plan?

Step one in the definition of response plans, is the identification of all potential preliminary alternate routes within the corridor. The list will undergo several iterations to refine the number of options and match them with available ITS element resources. The list is later refined to include all necessary alternate routes for all through routes in the corridor. Funding may be necessary to purchase and install the traffic signals, traffic sensors and the necessary changeable message signs needed to guide travelers along pre-agreed upon alternate arterial routes.

 A response plan is not limited to a traffic re-route. Signal and metering light timing changes, equipment and personnel requests, and communication plans could also be deployed as a part of a response plan. Stakeholders define all response plan components and when and where they will be used. Rules are then developed in the form of: "If an event occurs at location X, do Y and notify Z." These rules are then processed by a rules engine, which evaluates many rules and determines the best response plan.

The rules engine must support a complex set of conditions to account for the complexity of incidents, considering factors such as time of day, day of the week, expected duration, location of the incident, and possible issues with alternate routes such as an active school zone. A response plan should also be scaled depending on the severity and length of the incident. For example, if two lanes of the freeway are expected to be closed for one hour, that would warrant a different response plan than if the two lanes were expected to be closed for ten hours or if the closure were to occur at 3am versus 3pm.

How does a response plan get deployed? First an incident must be identified and characterized with information such as its location, severity, and anticipated clearance time. For many projects, this will mostly be done by Caltrans TMC operators as they monitor the corridor 24/7. Information is then passed to the Decision Support System (DSS) which will use the rules engine to suggest one or more response plans. Simulation models are then used by the DSS to rank the possible response plans based on how much improvement each is likely to provide. Depending on the situation, the top response plan could then be automatically implemented or reviewed by transportation management staff who could either implement, modify, or reject the response plan. The time necessary to complete this process will vary according to how the entire system is designed and operated but should take less than 10 minutes from start to finish.

The response plans (include re-routes), DSS, and rules engine will need to be modified as needed for the life of the ICM project. New construction, transit service changes, or a number of other issues can impact the corridor and require updated response plans for the betterment of the corridor.

 

flow chart of role of rules engine

 

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Over a period of months, the ICM project development team will need to work closely with stakeholders to refine the high-level design for the ICM Core System. This system comprises the majority of the IT infrastructure for the ICM system, with its three major components: the data hub, decision support system, and the corridor management system. The proposed system design is characterized by:

  • Storage (potentially cloud-based) design for flexibility, on-demand scalability, redundancy, and low deployment and operational costs
  • Multiple database technologies for optimized performance
  • Separate data management, decision support, and control functions for configurability
  • State, regional, and local layer design with flexibility for future scaling to other ICM corridor

View additional information on ICM System Components.

Decision Support System

Decision Support is a set of automated processes that assist human operators in making decision involving large amounts of data, multiple solution sets, and knowledge captured as rules. Decision support functions are used in multiple places within the ICM system. Decision support functions are meant to be used in multiple places by ICM system components and include the following reusable functions:

  • Rules capture and evaluation
  • Determination of the current state of the corridor based on limited data. When evaluating response plans, it is that analysis start with knowledge of the current conditions and state of the corridor
  • Prediction of the future state of the corridor based on limited data. When evaluating response plans, it is important to consider the likely future state of the corridor
  • Rules to determine whether corridor travel conditions are within normal expectations

Core functionalities of the ICM system are illustrated by the two circles at the center of the figure below. The inner circle, labeled DSS for Decision Support System, represents the system components that will be tasked with making decisions. Surrounding this circle, the circle labeled ICM represents various supporting functionalities of ICM system, such as data processing and communication with external systems.

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Data Hub

Data from each of the data sources are received by the ICM data hub. The primary functions are:

  • Receive data from field elements via center-to-center communications
  • Process data received from these field elements
  • Share or transmit data to the other systems via internal data bus
  • Data persistence

Corridor Management System

The Corridor Management System is the primary user interface and allows for management of the response plan lifecycle and ICM system.

Data Sources/Center-to-Center Communications

Field data sources include traffic signals, ramp meters, loop data sensors, and changeable message signs. Software systems are required to connect these field elements to the data hub and therefore to the Decision Support System. These software systems are called center-to-center communications. Sending and receiving information from the various field elements is required to activate corridor-wide response plans.

Each stakeholder may have multiple software systems in place and may require upgrades to enable system integration. In addition, it may also be necessary to install additional field elements to support the project.

For example, on a sample corridor the following five different center-to-center communication systems required integration into the ICM system.

TransCore - TransSuite The TransSuite system is used to provide two separate C2C interfaces. The first connects the City of Arcadia's TransCore system to the ICM core system. The second connects the Caltrans TSMSS system (a version of TransCore) to the ICM core system.
 Advanced Transportation Management System This system controls Caltrans' changeable message signs and ramp meters.
Kimley-Horn - KITS  The KITS system will provide the interface between the core ICM system and LA County, the City of Duarte, and the City of Monrovia.
McCain - Transparity The Transparity system will provide the connection between the core ICM system and the City of Pasadena.
Dynamic Message Signs The final C2C connection is between the dynamic message sign central control software and the ICM core system. The contract for development of this interface has not yet been awarded, so the vendor is yet to be named.

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