Institutional and Operational Elements

Institutional Needs (the "people" and the "organizations")

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. In most of the stakeholder and expert interviews, these institutional requirements were identified as the requirements most affecting the success of an ICM effort, and it 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 KSAs (knowledge, skills, and abilities)
  • 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 (MOUs) and other agreements with stakeholders, organizations, agencies, and/or private companies and ensuring that they remain updated

CT Internal Changes for Corridor Management

SMG and ETC were the consultants for the “Organizing of District 7 Traffic Operations for Corridor Management” effort. The goal was to help CT D7 align the Division of Traffic Operations with the principles of system management in order to maximize the performance of the existing and future transportation system. The project addressed only District 7 as a pilot that other urban districts could use as a “template” in the future.
The project called for developing several organizational charts, presenting them to District management, and revising them to ultimately lead to a more detailed, preferred option. Then the consultants worked on an implementation plan. This work was done via a Strategic Team that was assembled to oversee the project from beginning to end.
The consultants came up with four organizational options that were vetted with executive management, Operations Office Chiefs, Senior Operations staff, and the Strategic Team. Ultimately, Option 4 was selected as the preferred option by staff at all levels. The preferred option builds off of the prior reorganization work done in the District to organize geographically and staff support will be assigned under a Corridor Manager. This 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 (the “long-term option”).

View full-size image (1)
corridor managment organizational chart

This option 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:

This option 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

Kimley-Horn KSAs, Performance Metrics, etc.

Caltrans HQ is currently managing a contract with Kimley-Horn entitled “Organizing for Corridor Management” that has six deliverables. The deliverables are in the draft stage and include: The 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 Training Plan, and a sixth deliverable that is under development. The deliverables from this contract will be shared when they are final.

Performance Metrics

Key performance measures for the following areas will be developed and tracked for the I-210 Pilot:

  • 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

From the I-210 Concept of Operations: The ability of the ICM system to produce corridor improvements satisfying all stakeholders will depend on the metrics used for assessing corridor operations.  The selection of such metrics is a somewhat complex problem, 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 corridor operations.  This will not only simplify data processing needs, but also facilitate the understanding of the decisions made by the ICM system.  In this perspective, based on corridor stakeholder input and experiences from other ICM systems, the following base metrics are suggested for evaluating corridor performance:

Potential Corridor Metrics

Category

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 travel time

 

Median travel time

 

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 period)

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.  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 these metrics should be combined to determine recommended response plans, will be determined collectively by corridor stakeholders during the design phase of the ICM system.

The following are Performance Measure Targets from the ICMS Concept of Operations for a Generic Corridor produced by the FHWA:

Average Travel Time per Trip for the corridor and each network (includes long and short trips)
  • Corridor – 20 minutes
  • Freeway – 15 minutes
  • Freeway HOV – 10 minutes
  • Arterials – 25 minutes
  • Rail – 20 minutes
  • Bus – 25 minutes
Average Delay per Trip for the corridor and each network
  • Corridor – 10 minutes
  • Freeway – 5 minutes
  • Arterials – 7 minutes
  • Rail – 5 minutes
  • Bus – 8 minutes
Travel Time Index
  • Corridor daily vs. off peak – 1.2
  • Corridor Incident vs. peak – 1.3
  • Freeway daily vs. off peak – 1.1
  • Freeway incident vs. peak – 1.4
  • Arterials daily vs. off-peak – 1.3
  • Arterials incident vs. peak – 1.4
  • Rail daily vs. off peak – 1.0
  • 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 percent
Average parking availability per facility per time of day
  • Zero average availability at end of peak period only 90 percent of the time
Customer satisfaction as obtained from traveler surveys
  • 80 percent overall satisfaction with corridor
  • 80 percent satisfaction with corridor traveler information and accuracy

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 can be expanded. 

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

View full size image (2)


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:
    View full-size image (3)
    illustration of informaiton needed for modeling and simulation
  • Some of the processed data is used to construct the model, some to calibrate the model, and some 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

The model is vital to the I-210 Pilot and is currently one of the largest corridor micro-models in the country.  The model extends about 16 miles in the east-west direction, and about 4 miles in the north-south direction. It contains 4064 sections,
1620 nodes, 389 centroids, 459 signalized intersections, 62 freeway ramp meters, 94 Transit Lines (light-rail, buses), 819 Transit Stops, and over 1000 lane-miles of roadway. The signal plans and transit time tables cover 24/7 traffic operations.

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 do trips originate, which routes are taken, etc. New sensors, one of the improvements funded through Metro’s Call for Projects, will help fill some critical gaps and the team continues to work with stakeholders to fix existing sensors. 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 the I-210 Pilot, the 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 do we decide – 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, was the identification of approximately 300 preliminary alternate routes within the corridor. The list went through several iterations to refine the number of options and match them with available ITS element resources. The list was later refined to approximately 60 alternate routes for both the east and west directions. Funding approved by Metro and Caltrans was identified to purchase and install the traffic signals, traffic sensors and the necessary changeable message signs needed to guide travelers along these pre-agreed upon alternate routes.  

A response plan is not limited to just 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 are currently defining all these response plan components and when and where they will be used. Rules are being developed in the form of: “If an event occurs at location X, do Y and notify Z.” These rules will be processed by a rules engine, which will evaluate many rules and determine the best response plans.

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.

So 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 the I-210 Pilot, this will mostly be done by Caltrans TMC operators as they monitor the corridor 24/7. This information will then be passed to the Decision Support System (DSS) which will use the rules engine to suggest one or more response plans. Simulation models will then be 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. It will take approximately 10 minutes for this process to take place from start to finish.

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

View full-size image (4)
flow chart of role of rules engine