Project Planning

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 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

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

• 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

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

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

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

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

• 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

• 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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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

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 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.

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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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 include:

• 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