Deploying Advanced Technology Infrastructure for Transportation Systems Management & Operations in Maryland: US 1 Innovative Technology Deployment Corridor
Appendix H: Additional Performance Metrics
Improvement in System Reliability
Better freeway-arterial operations will improve system reliability, and the elements of this project are geared towards producing benefits in this area. For a motorist, knowing that one can expect a reliable commute with fairly stable travel times, even when incidents occur, is an ideal scenario. This project, through combined freeway and arterial operations efforts, will use the equipment and strategies being proposed to manage recurring and non-recurring congestion issues and facilitate greater system reliability within the corridor, which, as mentioned before, will also provide benefits to other routes within the regional transportation network.
Travel Time & Travel Time Reliability
Travel time and travel time reliability as experienced by the end user can be directly sampled by re-identification data, while central tendencies are reflected by probe data. The data and approach provide the ability to benchmark performance by the hour and across time, show the portion of the travelers that experience good versus poor performance, and support all major forms of travel time and reliability metrics such as a Travel Time (TTI), Planning Time Index (PTI), and Buffer Time Index (BTI).
Percent Arrivals on Green
Whereas re-identification provides effective metrics for a network of signals, high-resolution controller data detail the performance of individual signalized intersections. In addition to mining the hi-res data for streamlining maintenance, the sensor actuation data combined with SPaT can be utilized to judge the health of signal coordination by measuring the percent of vehicles that arrive on the green phase. This will provide an effective visual of the quality of progression, which can be cascaded to all signals in a corridor.
Capacity Utilization at Intersections
The inability of vehicles to clear a light on a single cycle evokes dissatisfaction and complaints. Techniques to monitor capacity utilization and the frequency of split failures are available through the available data streams. These metrics will tell the agency when demand for a movement is over-capacity and the phase requires more green – or if multiple phases are repeatedly failing simultaneously, the agency can optimize the network with the minimal wasted capacity.
Red-Light and Back-of-Queue Collision Reduction
In addition to the RLVW application through the CAV deployment, MDOT SHA will be able to share its real-time SPaT data with third party traveler information and navigation providers to alert users of impending red lights, queues ahead, etc. – This is already being piloted by WAZE and others in smaller regions. WAZE has interest in partnering with MDOT SHA for pilot implementations of various safety and traveler information initiatives. The first step would be to define performance measures that quantify the direct safety benefits of the deployments being considered.
