Dynamic Mobility Applications (DMA) Program

Multi-Modal Intelligent Traffic Safety System (MMITSS)

Multi-Modal Intelligent Traffic Signal System is the next generation of traffic signal systems that seeks to provide a comprehensive traffic information framework to service all modes of transportation, including general vehicles, transit, emergency vehicles, freight fleets, and pedestrians and bicyclists in a connected vehicle environment.

The vision for the MMITSS application is to provide overarching system optimization that accommodates transit and freight signal priority, preemption for emergency vehicles, and pedestrian movements while maximizing overall arterial network performance.

Research Plan

Traffic signal control has experienced very few fundamental improvements in the past 50 years. While tools and methods have been developed to enable traffic engineers’ better use of traffic signal control, the fundamental logic and operations of the controller have not changed. Further, most systems today depend on loop detectors or video-based systems that are located at fixed locations in space to call and extend signal control phases. These detection systems provide basic information such as vehicle count, occupancy, and/or presence/passage information. This limits the use of advanced logic that can potentially be built into modern day traffic signal controllers.

Modern traffic control management systems provide the ability to monitor signal operations, change signal control plans by time of day or in a traffic responsive manner, and some provide adaptive signal timing where the signal timing parameters are adjusted based on traditional vehicle detector data. Traffic management systems provide a traffic engineer the ability to manipulate signals from a central traffic control center, but have limited strategic control capability and rely heavily on the innovation and skill of the traffic signal engineer user.

The advances in Connected Vehicle technologies provide the first real opportunity for transforming traffic signal control in terms of the traffic signal controller logic, operations, and performance. The advent of Dedicated Short Range Communications (DSRC) in vehicular communication provides a critical component that, when coupled with meaningful messages (SAE Standards J2735-2009), has the potential to provide detailed information required for intelligent traffic signal control. DSRC can be leveraged to provide real-time knowledge of vehicle class (passenger, transit, emergency, or commercial), position, speed, and acceleration on each approach. The widespread availability of other wireless communications media (such as Wi-Fi, 3G/4G, and Bluetooth enabled Smartphones) provide coverage for other users including pedestrians and cyclists as well as coverage for other long-range messages from vehicles that can support traffic signal system management in areas with sparse deployments of DSRC roadside equipment. The potential for safer and more efficient multimodal traffic signal operations is finally possible.

To realize these new opportunities, the Multi-Modal Intelligent Traffic Safety System (MMITSS) applications bundle has been conceived. It incorporates, at a minimum, the following arterial traffic signal applications:

• Intelligent Traffic Signal System (ISIG): Using high-fidelity data collected from vehicles through V2V and V2I wireless communications as well as pedestrian and non-motorized travelers, this proposed application seeks to control signals and maximize flows in real time. The ISIG application also plays the role of an overarching system optimization application, accommodating transit or freight signal priority, preemption, and pedestrian movements to maximize overall network performance.

• Transit Signal Priority (TSP): This proposed application allows transit agencies to manage bus service by adding the capability to grant buses priority based on a number of factors. The proposed application provides the ability for transit vehicles to communicate passenger count data, service type, scheduled and actual arrival time, and heading information to roadside equipment via an on-board device.

• Mobile Accessible Pedestrian Signal System (PED-SIG): This application integrates information from roadside or intersection sensors and new forms of data from pedestrian-carried mobile devices. Such systems will be used to inform visually impaired pedestrians when to cross and how to remain aligned with the crosswalk. This application may also support the accommodation of safe and efficient pedestrian movement of a more general nature.

• Emergency Vehicle Preemption (PREEMPT): This proposed application, while similar to existing technologies, will integrate with V2V and V2I communication systems. The application would account for non-linear effects of multiple emergency responses through the same traffic network.

• Freight Signal Priority (FSP): This application provides signal priority near freight facilities based on current and projected freight movements. The goal is to reduce delays and increase travel time reliability for freight traffic, while enhancing safety at key intersections.

The interaction of these applications, as part of the connected vehicle environment, provides a transformational opportunity to change the fundamentals of traffic signal control. The final goal is to field test or demonstrate MMITSS.