Cross-cutting Issues

The paper develops a reactive-driving agent based algorithm for modeling driver left turn gap
acceptance behavior at signalized intersections (in right-hand traffic). This model considers
the interaction between driver characteristics and vehicle physical capabilities. The model
explicitly captures the vehicle constraints on driving behavior using a vehicle dynamics
model. In addition, the model uses the driver’s input and the psychological deliberation in
accepting/rejecting a gap. The model is developed using a total of 301 accepted gaps and
subsequently validated using 2,429 rejected gaps at the same site and also validated using
1,485 gap decisions (323 accepted and 1,162 rejected) at another site. The proposed model is
considered as a mix between traditional and reactive methods for decision making and
consists of three main components: input, data processing and output. The input component
uses sensing information, vehicle and driver characteristics to process the data and estimate
the critical gap value. Thereafter, the agent decides to either accept or reject the offered gap
by comparing to a driver-specific critical gap (the offered gap should be greater than the
critical gap for it to be accepted). The proposed modeling framework can be generalized to
capture different vehicle types, roadway, movement, intersection characteristics, and weather
effects on driver gap acceptance behavior. It is anticipated that these findings may be used to
develop weather-specific traffic signal timings and also for the future of vehicle-to-vehicle
communications.

Authors: Ismail Zohdy, Hesham A. Rakha

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida

A common method of Dilemma zone (DZ) protection at isolated intersections is to hold the green until the number of vehicles in DZ is lower than a threshold number. Since the threshold number is empirical and fixed, it cannot accommodate the dynamic and time-varying traffic patterns and therefore have to be adjusted regularly. This paper presents a new Markov-process-based DZ protection algorithm, which considers each time step, the algorithm first predicts the future states with the Markov state-transit matrix then compare them with the current state to determine whether to end the green or not. As a result, the new end-green criterion is determined not by the fixed threshold values but by the current state and the Markov state-transit matrix. Meanwhile, the Markov matrix is automatically updated when the new observed detected state transitions come in. The simulation results showed that the new algorithm maintains reliable and effective protection in a dynamic traffic environment. At last, we present an evaluation of the new algorithm performance using two methods of calculating the current state: low-fidelity prediction with advance detectors and high-fidelity prediction with future Connected Vehicles Technologies.

University of Kentucky

Virginia Polytechnic Institute and State University

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida

Under the initiative of U.S. Department of Transportation a safety-critical, dual redundant, open source traffic signal control application is currently being developed. The system named SCOPE, for Signal Control Program Environment, currently implements standard 8-phase NEMA logic and some concept of the National Cooperative Highway Research Program3-66. SCOPE is designed to be part of the Advanced Traffic Controller (ATC), making use of API standard 2.06b to integrate with the hardware. In addition to executing on the ATC platform, SCOPE can run on desktop workstations and PowerPC Linux based prototype boards. It is easily ported to any CPU. Safety-critical status is achieved through redundancy of application logic that constantly compares expected signal phase information. From baseline requirements, engineers independently program application code, one using Ada95 andthe other using C++. The Traffic EXperimental Analytical Simulation (TEXAS) Model is currently used for validation and testing with Formal Qualification Testing to occur late in 2011. Upon validation and subsequent release to the open source community SCOPE will provide users the ability to replace the proprietary application software residing in ATC cabinets. Transparency will be provided into another aspect of the traffic control signal thus taking the initiative of ATC one step further.

University of Central Florida

Advanced Technologies Incorporated

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida

Accommodating pedestrians at urban intersections is challenging as multimodal service demands compete highly on limited green time. Highway Capacity Manual prescribes the parallel vehicle green must exceed "WALK" plus "pedestrian clearance interval (PCI)" timed by a design walking speed. This static "PCI" timing is unsafe since seniors or children are usually slower than the design pedestrian. Furthermore, a vehicle flow issue arises when the prolonged "PCI" exceeds the operationally efficient parallel green: additional vehicle right-of-way, unnecessary for operational efficiency, preempts green time from a conflicting phase, increasing intersection-level queuing delays. It is necessary to achieve a tradeoff among competing multifaceted traveler needs. A pedestrian-detection-based NEMA signal system was developed for an urban isolated intersection. During each phase, the dynamic "PCI" function offers all pedestrians the crossing time in real-time need. In simulation setting, the new signal system was evaluated against the conventional NEMA system adopting two design walking speeds and proved advantageous for protecting pedestrians and offering competitive performance.

University of Vermont

Department of Civil Engineering & Environmental Engineering

Research Center for Groundwater Remediation Design

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida

The experience at the Mid Region Council of Governments (MRCOG) has shown that

coordination among ITS stakeholders at the planning, policy, and technical levels provides

critical benefit to ensure that ITS is deployed in a fully integrated manner. To this end, our ITS

stakeholders have involved themselves directly or indirectly at nearly all phases of project

development ranging from initial project planning, project design and implementation, and

finally with coordination with systems operators and data users upon project completion. The

MRCOG, as the Metropolitan Planning Organization (MPO), is responsible for carrying out a

collaborative transportation planning process for agencies within the urbanized region. The

supporting committee structure facilitated by MRCOG involves agency representation ranging

from elected officials comprising the Metropolitan Transportation Planning Board (MTB) to the

supporting technical committees comprised of all levels of staff such as department heads and

technical project planners, engineers, managers, and the public. It is in this capacity as

coordinating facilitator that the MPO’s ability and opportunity to be a central point of regional

transportation planning consensus has proven itself a powerful mechanism in the pursuit of ITS.

Council of Governments

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida