Cross-cutting Issues

Over the past two years, the South African National Roads Agency Limited (SANRAL) engaged in a comprehensive assessment of its overall Intelligent Transportation System Program. This assessment included its existing ITS deployment and operations in the Gauteng Province as well as plans and systems for its recently commissioned deployments in the provinces of Kwazulu-Natal and the Western Cape. The assessment resulted in the identification of several areas for which SANRAL could enhance the level of benefit it was delivering to the travelling public. These included modifications to their institutional environment as well as enhancement and expansion of their operations and systems. To implement the operations and systems changes, SANRAL assessed several approaches and elected to go out on Tender to acquire the services of a DBOM contractor. The DBOM contractor is to operate SANRAL’s three Transportation Management Centers, expand the deployments in each region in accordance with the Agency’s strategic deployment plan and concept of operations, and provide and implement new systems software. This paper describes the procurement and evaluation process, the procurement vehicle and some lessons learned.

South African National Roads Agency Ltd

Techso

Kimley-Horn and Associates, Inc.

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

Priority control systems, whether vehicle, central control or intersection based, are all composed of hardware devices running software programs. These devices may include, but are not limited to, signaling emitters, signal detectors, intersection communications devices, and assorted associated supporting devices.

The traditional use of priority control has been to implement emergency vehicle preemption (EVP). Emergency vehicle priority preemption of normal traffic signal operation provides safe, rapid progress for authorized emergency vehicles through priority control equipped intersections. If an EVP request is forwarded to, and granted by the intersection controller, a green light is applied to the phase requested by the requesting vehicle or agency. Since this detection occurs in real-time, and by the nature of the request priority, there is little chance that emergency vehicles will be denied a green light.

Global Traffic Technologies

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

Microscopic simulation can provide significant support to traffic management center (TMC) operations.  However, traffic simulation applications require data that are expensive and time-consuming to collect.  Data collected by TMCs can be used as a primary source for the provision of the required data.  The goal of this study is to explore the development of methods and tools for the use of microscopic traffic simulation models to support the TMC software implementation, operation, and testing on one hand, and the use of ITS data to support the development and calibration of simulation models on the other. 

The study developments include methods and software utilities that use the existing TMC databases and other available information for the preparation and calibration of microscopic simulation tools.  In addition, the development includes methods and utilities to support testing of the TMC software modules and data archiving processes. The use cases of this study demonstrate the capabilities of the developed simulation environment, which can provide a powerful support for the evaluation of TMC software.  In addition, the environment can provide an effective mechanism for operator training with the TMC software.

Department of Civil and Environmental Engineering

Florida DOT

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

Methods to effectively monitor arterial traffic have commanded center stage as new tools and technologies such as vehicle probe data and Bluetooth^TM traffic monitoring have emerged to cost-effectively provide accurate, real-time, continuous, network-wide monitoring of freeway systems.  Within metropolitan areas, the network of high-volume, multi-lane arterials is critical to the daily movement of commuters to jobs and services, to distribute freeway traffic to local streets, and to provide diversion routes during major incidents.  Many of the same technologies that have revolutionized freeway traffic monitoring promise to do the same for signal-controlled arterials.  However, initial demonstrations and implementations reveal a variety of issues, many of which are inherent to the fundamental nature of traffic flow that differentiates arterials from freeways.  The I-95 Corridor Coalition’s Vehicle Probe Project (VPP) has successfully delivered high quality freeway travel time data on a roadway network comprised of over 5,000 centerline miles since its inception in 2008. The project also includes a component consisting of approximately 900 miles of arterials that link the major freeways and provide diversion routes in the event of incidents.  The validation program that monitors data quality for freeways also collects data samples on the arterial network. This paper characterizes the critical challenges in providing quality traffic data on arterials based on data collected as part of the I-95 VPP and through interaction of a committee of transportation professionals that provide guidance to the project.  The findings from the I-95 VPP are germane to any probe-based arterial traffic monitoring system.

University of Maryland

KMJ Consulting, Inc.

I-95 Corridor Coalition

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

The primary objective of this paper is to study and analyze the temporal characteristics of
traffic congestions and the associated speed distributions for congested expressways based on
the Floating Car Data (FCD) in Beijing. First, the temporal distributions of congestions with
different intensities are analyzed using the FCD of 5 workdays for a particular expressway
Link N26376. Results show that the longer the continuous congestion lasts, the lower the
speed distribution interval is. Then, the distribution curve is fitted, which finds that the
Log-Logistic model can well describe the survival function distribution of the severe
congestion durations for morning peak-hours of Tuesday. By comparison, it is found that the
duration distribution value of severe congestions at the aggregation interval of 2-minute is
lower than that at the 5-minute interval, and the duration distribution value of severe
congestions on Link N26376 is higher than that on its downstream Links N24162 and N23971.
Finally, the speed distributions in two proposed categories of congestion periods are analyzed
and compared. Results show that if the speed in the present time period falls in a higher
distribution interval, then the probability that the severe congestion will dissipate in the next
time period will be higher.

Authors: Lin Zhu, Lei Yu, Huimin Wen

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