Cross-cutting Issues

The Colorado Department of Transportation (CDOT) is preparing a three-tiered communications network strategy that is intended to be deployed throughout the state. The first tier (Tier 1) is a statewide network connecting all of the CDOT offices. The second tier (Tier 2) is a regional network connecting CDOT offices, cities, counties and other agencies. The third tier (Tier 3) is a local network that is intended to reduce fiber needs along each corridor and provide system access throughout the Tier 1 and 2 networks. The intent of this three-tiered network is to provide a statewide standard for communications for Intelligent Transportation Systems (ITS) to meet the growing demand for a statewide system. By providing this standard both new and existing ITS deployments can be designed to tie into the statewide communications network, thus providing the opportunity to share data and video throughout the state. This paper describes the concept of the Tier 3 communications network. The development of the Tier 2 network has been described in previous papers presented at ITS America in 1998 and 1999. The development of the network, including a “proof of concept” stage are occurring during late 2000 and early 2001, and will be added to the final paper.

Kimley-Horn and Associates, Inc.

Colorado Department of Transportation

Presented at the ITS America Annual Conference and Exposition, June 4-7, 2001 Miami Beach, Florida

Many technological advances have enabled new methods of collecting transportation data that can be used to plan and maintain effective roadway policies. Automated license plate reading technologies are beginning to gain acceptance because of the wide range of applications to which they can be applied. Typically, automatic license plate reading (ALPR) systems are used for enforcement type applications and data collection applications including parking lot management, origin-destination studies, traffic flow studies, high occupancy vehicle analysis, and weigh in motion systems. An ALPR system consists of three main components; a device for detecting vehicle presence, a digital video camera and an image processor. The image processor identifies the license plate according to embedded pattern recognition algorithms. The accuracy of the pattern recognition algorithms used in the image processor is an important concern when evaluating ALPR systems. The required accuracy depends on the application. For example, an enforcement application may require a high degree of accuracy while a traffic flow study may only require that an image obtained at an entry point be matched to an image obtained at an exit point. Other issues for consideration when evaluating ALPR systems are mobility and simplicity of use, range of vehicle types that can be read, necessary lighting conditions, range of states of origin that can be read, range of vehicular volumes and speeds that do not overload the image processor, and human impact/public relations.

Department of Industrial Engineering, University of Arkansas

United States Navy

Presented at the ITS America Annual Conference and Exposition, June 4-7, 2001 Miami Beach, Florida

A preliminary study revealed that Washington State Department of Transportation’s dual-loop detection system was not functioning properly. In order to identify types and severity of dual-loop errors, an in-depth evaluation on the accuracy of aggregated dual-loop data was performed. The sample dual loops were all under optimal working condition, which minimized the possibility that system failure resulted in inaccurate loop measurements. Aggregated dual-loop data were compared to video data on 20-second intervals so that errors were captured whenever they occurred with an error range of ±20 seconds. Two major errors, miscount and misclassification, were quantitatively identified; possible causes of dual-loop errors were investigated; further research directions were also recommended.

University of Washington

Presented at the ITS America Annual Conference and Exposition, May 19-22, 2003 Minneapolis, Minnesota

Data from inductive loop detectors is widely used as input to many ATMS applications. However, for several reasons, loop detectors are prone to failures. This leads to erroneous data that significantly reduces the accuracy of the applications that utilize detector data as input. The work that has been done in the past to develop procedures to test the quality of detector data is inadequate since there are several forms of corrupt data that still remain undetected. Moreover, procedures to correct erroneous data identified are also lacking. This paper presents an improved procedure to test the reliability of detector data as well as a procedure for correcting erroneous data. The data screening and correction procedure is applied to detector data from sensors of a real freeway section to demonstrate its effectiveness and applicability.

University of Minnesota

Presented at the ITS America Annual Conference and Exposition, May 19-22, 2003 Minneapolis, Minnesota

An Intelligent Transportation Systems (ITS) communications architecture is emerging with ITS-specific standards for several layers of the International Standards Organization Open Systems Interconnections (OSI) communications reference model. However, these standards neither fully leverage the advantages of a standards-based architecture, nor fully address ITS-specific security and networking requirements. This paper rectifies these shortcomings by describing a reorganization of the emerging standards and the addition of protocols for two additional OSI layers. The result is an improved communications architecture for ITS networks.

The George Washington University

Presented at the ITS America Annual Conference and Exposition, May 19-22, 2003 Minneapolis, Minnesota