Cross-cutting Issues

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.

Authors: George X. Lu, David A Noyce, George F. Pinder

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 the number of vehicles in DZ (state) as a Markov process. At 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.

Authors: Pengfei Li Ph.D., Montasir M. Abbas, Ph.D., P.E., Raghu Pasupathy, Ph.D.

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

Integrated Corridor Management (ICM) and Active Traffic Management (ATM) have currently captured the practitioners’ imaginations in the USA. ICM allows for the integration of all facility types (freeways and arterials) and modes along a specific corridor, and optimizes flow for all modes of transportation. ATM optimizes the flow along a given section of freeway by utilizing hard shoulders as an extra lane during peak hours, ramp metering, and variable speed limits.
Individually, each of these is a powerful tool in the hands of operators that can significantly improve the quality and quantity of transportation capacity along specific links and corridors. Various corridors have been identified for the implementation of both ICM and ATM across the US, but to my knowledge there has not been a corridor identified that incorporates both. Together, these two tools are capable of transforming transportation in the US and creation of remarkable improvements and benefits for both the transportation operator and transportation users. Ultimately, the combination of these two tools into a single management tool will allow us to operate and manage facilities to optimize corridors in a real-time manner to address both normal peak hour congestion and those conditions caused by incidents.

Authors: Joel K. Marcuson

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

Delivery of Intelligent Transportation Systems (ITS) as part of a large design-build project

results in numerous challenges for government contracting agencies. This paper presents the

challenges faced by the Washington State Department of Transportation (WSDOT) in

developing design-build contracts for the delivery of ITS on several large design-build

transportation projects over the last ten years. This paper describes the two-phase selection

process – Request-for-Qualification (RFQ) and Request-for-Proposal (RFP), and innovated

procurement strategies that WSDOT has used on its design-build contracts with a focus on

ITS delivery. A key discussion will include how to use the Systems Engineering Process (SEP)

in design-build and how to provide flexibility and encourage design-build contractor (designbuilder)

innovation while meeting existing system integration requirements. This paper also

outlines several significant findings from the recent SR 520 Bridge Replacement and HOV

design-build projects. Finally, recommendations are provided for addressing ITS delivery

issues on large design-build transportation projects.

HDR Engineering, Inc.

Washington DOT

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

Early intelligent transportation systems (ITS) were integrated exclusive of standing
information technology (IT) departments. The closed, isolated nature of these systems
enabled the ITS network to avoid existing IT security issues and policies. Typically, these
systems were dominated by low bandwidth, serial communication technology in concert with
analog signal transmission for closed circuit television cameras (CCTVs). With the
emergence of Ethernet/Internet Protocol (IP) networks, cost efficient high quality digitized
video, and a desire to share data with partner agencies, ITS networks transitioned from
segregated networks to merged networks where IT professionals, ITS engineers, and
transportation managers find themselves working hand in hand toward similar objectives.
This paper explores the challenges, successes, and lessons learned from real world ITS/IT
collaborations.

Authors: Mark Dunzo, Debbie Self, Cole Dagerhardt

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