Integrated Corridor Management Initiative – ICMS Surveillance and Detection Needs Analysis for the Transit Data Gap

7.0 Transit Data Types and Performance Measures

7.1    Overview of Transit Performance Measures

Transit performance measures can be divided into two categories:  quantitative and qualitative. The quantitative category elements are typically measured on a route basis. These include:

1. Number of passengers per vehicle mile
2. Number of passengers per revenue hour
3. Speed
4. Travel time
5. Passenger/Platform wait time
6. Schedule adherence
7. Headway regularity
8. Cost per passenger
9. Cost per revenue mile
10. Cost per revenue hour

The qualitative category reflects systemwide performance and includes:

1. Quality of service from the consumer’s point of view
2. Effectiveness of routing
3. Effectiveness of scheduling

The consumer’s view of the quality of service is dependent upon the convenience of the routes and schedules, the availability of parking, comfort, speed, safety, and reliability of the system.

Other transit performance measures also exist. The additional measures are related to region-specific issues such as source of funding, employment opportunities, mobility service requirements, and regional policies.

7.2    Pioneer Site Performance Measures

Many of the pioneer sites expressed a need for the ability to provide travelers with enough information to compare travel times between freeways, arterials, and transit as a means to promote mode shift and improve the performance of the ICMS. In order for a mode shift to occur, there needs to be unused transit and associated parking capacity which is readily available to the traveler so that the destination can be reached in a reasonable length of time. Transit performance measures which were identified to assist with this were:

1. Transit vehicle schedule adherence
2. Transit vehicle speed/travel time
3. Transit vehicle capacity which is sometimes referred to as “Passenger Crowding.”
4. Parking space utilization/availability

Each site identified improvement in overall throughput of the corridor as a desired performance measure. In order to demonstrate improvement, the current level of corridor throughput must be calculated across all modes of transportation and all segments of the participating networks. The following surveillance and detection capabilities as defined in Section 3.2 are needed to calculate the improvement:

1. Freeway and tollway monitoring
2. Transit monitoring
3. Arterial monitoring

In addition to corridor throughput, each pioneer site identified specific performance measures for the corridor that were desired. These included:

1. Travel time including mean, maximum, buffer, and range
2. Vehicle speed
3. Travel delay time and predictability
4. Incident duration and frequency
5. Fuel consumption savings
6. Pollutant emissions savings

Some of the pioneer sites identified specific performance measures for the freeway, transit, or arterials. The performance measures identified for transit included:

1. Transit speed based on transit vehicle AVL data
2. Transit capacity based on APC data
3. Transit frequency
   • Number of passengers per route
   • Number of passengers per service type
4. Transit route performance
   • Travel time
   • Trip mileage
   • Passenger/Platform wait time
   • Dwell time
   • Number of passengers per mile
   • Average passenger load
5. Schedule adherence
6. Parking lot utilization

7.3    Performance Measures for ICMS

Performance measures figure heavily in the design and expansion of transit systems. Most transit planning is based on current demand and forecasts of future demand based on demographic measures such as population growth, population shifts, new construction, and economic forecasts of fuel costs and operator salaries. These studies are essentially a demand forecast which is then equated to a capacity requirement. The modeling exercise is focused on determining where to add capacity, how much capacity to add, and how to add the required capacity in the most cost-effective way.

Current models that handle multiple transportation modes typically use a cost per unit of additional capacity as a measure of comparison between alternatives involving multiple modes of transportation within the planning model. As a performance measure for planning, incremental cost of construction/procurement for equivalent capacity works for comparing multiple transportation modes.

Incremental cost of construction/procurement does not work for real-time management or event planning. This difference between construction/procurement planning and operational planning establishes a time-event horizon between construction/procurement planning and operational planning and management. Real-time management and event planning must be based on the assets at hand. This means that controls and strategies for operation of corridor assets must be based on using existing assets without exceeding capacity limits.

The forward-looking nature of event planning allows operations staff to move or re-allocate existing transportation resources. Real-time responses do not usually result in changes to existing transportation mode capacities.

Real-time responses to incidents call for messages on existing Dynamic Message Signs and Highway Advisory Radio, as well as information broadcasts to the public through the media, text messaging, and the Internet. The responses may require lanes or entire roadways to be closed. In the case of incidents involving transit, schedules may be disrupted or routes altered or dropped for a short time. For incidents lasting less than an hour or two, route shifting and travel plan changes are the primary responses to the reduced capacity caused by the incident.

Event planning may involve substantial modifications to the deployment of equipment, and the allocation of lanes, roadways, intersections, and other capacity-related assets. The differences between events (construction, parade, or large venue event) and disaster planning (evacuations, road closures due to flooding, weather, or roadway damage) are more a matter of degree than method. For example, planning can involve capacity changes such as:

1. Transit vehicles can be added to and/or diverted from established routes to expand transit capacity between desired locations.
2. Transit vehicles can be given dedicated lanes or rights-of-way.
3. Temporary parking areas can be opened to facilitate additional transit utilization.
4. Event related timing plans can be implemented on arterial signal systems.
5. Intersections can be closed and detour routes established to modify conventional traffic patterns.
6. Lanes or whole roadways can be closed and detour routes established.
7. Lanes or roadways can be blocked and put into contra-flow operation to expand capacity in desired directions.
8. Portable Dynamic Message Signs and CCTV cameras can be deployed to key locations to provide additional surveillance and direct communication with travelers.

The goal of incident management is to keep an incident from cascading into a situation where there is a substantial loss of capacity at a critical time, but incidents do frequently result in major congestion. The goal of ramp metering is to smooth out traffic density and manage volume to avoid recurring congestion on highways (without causing equally detrimental congestion on arterial roadways). The goal of transit priority-based signal strategies is to quickly move people in high occupancy vehicles without creating traffic problems for people in other vehicles. None of these goals are conflicting unless, and until, they negatively impact the capacity of other transportation modes. Viewed as a common goal to maximize the utilized capacity to move goods and people through the corridor, a common feedback value can be derived that is suitable for evaluating and managing use of the corridor transportation resources. This concept establishes a basis for Integrated Corridor Management that can usually be agreed upon by all participants:

Integrated Corridor Management should be based on the concept of reducing or avoiding capacity overloading on all corridor transportation modes and maximizing the volume of people and goods moved through the corridor for any given transportation demand.

To achieve this goal, the ICMS must have the following information:

1. Data about each transit vehicle including capacity and amenities
2. Data about each route, run, stop, schedule, and payment option
3. Data about each parking lot including capacity, location, fees, and associated transit stops
4. Current information associating each operational vehicle with an assigned run, route, and schedule
5. Current information about each in-service transit vehicle – location (30 second reporting desired, 60 second reporting acceptable) and current passenger count (reported after each pull-out preferred, reported at 60 second intervals acceptable)
6. Current information about each parking lot – either current utilization or current un-utilized capacity (60 second reporting desired, 5 minute reporting acceptable)

In order to “reduce or avoid capacity overloading” it is necessary to know the capacity of the system, the current utilization of the system, and the overload point. Without knowing the current utilization of transit vehicles and parking lots, predicting capacity overloading before it happens is not easy. The key to an effective strategy is having timely information that will facilitate a timely response.

All of the pioneer sites have (or can obtain) the data listed above.

Of the eight sites, only San Antonio indicated that information about current parking availability would not be available to the ICMS. Three sites indicated they would estimate occupancy of parking lots and four sites indicated they would calculate the number of available parking spaces. Five of the sites indicated plans for disseminating parking information.

Only Montgomery County indicated that they plan to have current passenger counts for the ICMS. Three of the sites (Dallas, Oakland, and Minnesota) indicated that they plan to have estimated passenger counts (based on historical data).