U.S. Department of Transportation
Federal Highway Administration
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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
This magazine is an archived publication and may contain dated technical, contact, and link information.
|Publication Number: Date: Nov/Dec 1997|
Issue No: Vol. 61 No. 3
Date: Nov/Dec 1997
In 1991, the Intermodal Surface Transportation Efficiency Act established the Intelligent Vehicle-Highway Systems Program to improve mobility, reduce congestion, and enhance safety through the widespread use of advanced technologies. Over the first six years of the program, which is now called the National Intelligent Transportation Systems (ITS) Program, most of the initiatives and focus has been on finding high-tech solutions to the transportation problems of our congested urban areas.
Now, attention is also being paid to the many applications of innovative advanced transportation technologies to promote more efficient, safer, and more environmentally sensitive solutions for common transportation problems in lower populated, rural regions.
The Colorado Department of Transportation (CDOT), in cooperation with the Federal Highway Administration, instituted a series of ITS initiatives in Colorado to develop a rural ITS (RITS) program that satisfies current and future public transportation needs, including dynamic roadway and weather information, incident management capabilities, increased safety, and streamlined mobilization of goods and services. Colorado's commitment to enhancing rural traffic operations is demonstrated by the ongoing implementation of variable message signs (VMSs), traffic operations centers (TOCs), roadway weather information systems (RWISs), and other public safety applications. Building on its early years as a basic VMS network and its evolution as a dynamic weather prediction system, the Colorado RITS program progresses into a new era.
Preserving future service expansion and innovation were primary factors in the early development of Colorado's RITS open system architecture. The main objective for the program is to develop a series of technologically advanced infrastructure improvements that support a diverse range of public needs without depleting available financial reserves. Integrating leading edge advancements into the rural transportation infrastructure requires an understanding of how to manage and implement new technologies a cost-effective way. CDOT has demonstrated, through various lea els of user services and strategies, how RITS can benefit the public.
Variable Message Signs
Traffic operation centers were constructed during CDOT's initial phase of RITS development in the early 1990s. A variable message sign is medium through which a TOC is able to communicate important travel information to the public.
Several variable message signs in Glenwood Canyon provide safety and traffic flow information to motorists.
CDOT has installed strategically placed VMSs along the rural, high volume corridors of Interstate 25 and Interstate 70. The information provided through these VMSs includes weather conditions, inside management, and real-time route guidance during roadway delays. CDOT uses both high-resolution light-emitting diode (LED) VMSs; flip disk VMSs.
VMSs are monitored daily by regional TOC computer systems; through regular on-site field inspections by maintenance personnel. example, along I-70 near Glenwood Springs, the Hanging Lake Tunnel TOC controls approximately 50 VMSs throughout 280 kilometers of interstate highway in northwestern Colorado. TOC control-room operators use cellular-based technology to transmit information to VMSs. Analog modems at the sites monitor incoming data and translate it for the VMS system computers.
CDOT is currently upgrading the communications network with direct hard-wired fiber-optic lines for more responsive and instantaneous connections. Additional CDOT VMS improvements include development of a preprogrammed software protocol for sending routine messages. This process will expedite transmissions and minimize erroneous information transfers. The VMS network is cross-linked to weather stations through a server at the TOC and provides real-time weather conditions and information on hazardous roadway conditions to motorists.
During the winter season, avalanche control is a necessary safety provision along high-elevation mountain passes. Roadway closures associated with this activity create traffic delays throughout the corridor, The activated VMS network allows CDOT to provide important travel information to the public and to mitigate traffic delays by rerouting along alternative routes when avalanche control and other major incidents occur.
Roadway Weather Information Systems
To provide the most accurate array of information on weather, traffic, and pavement conditions, CDOT installed RWISs statewide. These sites measure various atmospheric conditions, including air temperature, precipitation accumulations, wind characteristics, relative humidity, and roadway visibility. CDOT upgraded several stations with features to monitor traffic data such as: volume, speed, occupancy, gap length, weigh-in-motion, and vehicle class.
This data is downloaded to a server where traffic management software analyzes conditions to improve traffic system performance and optimize signalization within rural areas. RWIS sites transmit information using an open protocol architecture (TCP/IP) to a server that uploads the processed data for distribution on the Colorado TOC local area network.
RWIS stations were originally intended to improve the coordination of weather conditions and CDOT winter maintenance operations; however, this system later evolved to become an integral part of the RITS network. Surface pavement sensors and depth probes are integrated within the pavement structure to measure surface and subsurface temperatures. These devices also measure moisture percentages. This data is essential for winter maintenance planning and chemical deicing activities and for increasing public safety during in clement weather conditions. Recent RWIS upgrades -- including video surveillance used for real-time dynamic roadway analysis, ramp metering, and monitoring traffic movements at high-volume, rural intersections -- increase the yearround value of the RWISs. CDOT is currently experimenting with software to integrate all video footage and other RITS information on an Internet site for viewing by the public.
Traffic Operations Centers
|Cellular emergency call boxes allow motorists to directly contact the nearest traffic opera-
tions center, which can provide an immediate response through com-
munications with local police and rescue dis-
Colorado's rural TOC network uses RITS technologies to respond to regional traffic needs. Current operational TOCs are the Hanging Lake TOC, Eisenhower Tunnel TOC, Colorado Springs TOC, and CDOT's central TOC located in the Denver metropolitan area. These TOCs currently function independently on separate platforms. Future plans include integration and cross-linkage of software and technology between the centers.
In addition to the connections to VMSs, the TOCs regulate cellular emergency call boxes and provide immediate response through communications with local police and rescue dispatch centers. Loop detectors are monitored for incident man- agement and evaluating traffic volumes, speeds, and classifications. The tunnels also contain carbon monoxide sensors, linear heat detectors, high-clearance warning systems for oversized vehicles, and AM/FM rebroadcast with an override system for sending emergency messages.
Automated weigh-in-motion (WIM) detection technology is currently deployed on several rural roadway sections within Colorado, including I-70 at Dumont and I-25 at Trinidad. This automatic vehicle identification system expedites the processing of commercial carriers through port-of-entry stations. Commercial vehicles equipped with a specialized transponder transmit important information on weight, materials, and the motor carrier's safety status to the port official. By minimizing commercial vehicle delays, mainline traffic congestion is reduced, and commercial traffic continues unimpeded. Currently, the Division of Motor Carrier Services does not require that commercial operators equip their vehicles with transponders; however, state records indicate that major carriers have adopted, installed, and are proactively using these transponders for interstate travel purposes.
Public Safety Applications
The safety of Colorado roads has been enhanced through several RITS initiatives. As part of a continuing effort to take advantage of technological solutions to safety problems, CDOT has implemented radar-induced smart signs. This technology uses infrared speed detection technology combined with a VMS to give motorists advanced warning for possible speed-induced rollovers on slopes and curves. CDOT targeted this technology at commercial vehicle operators and the public.
The effectiveness of this application was demonstrated on a hazardous curve on I-70 in the Glenwood Canyon. Prior to installation of the system, this area experienced several severe truck rollover accidents. The warning system has significantly reduced accident frequency, and this model provides CDOT with a cost-effective and safe application for future statewide deployment.
Recently, CDOT used a RITS application to address the issue of head-on accidents along interstate on/off ramps. This project uses inductive loops in the pavement to activate strobe warning lights that are mounted on signs. The logic-based computer system, through data received from the loop detectors, determines if a vehicle is traveling in the wrong direction and then initiates commands to activate the strobe lights to warn the driver.
Similarly, in southern Colorado, bikers on narrow roadways can inform motorists of their presence by manually activating a blinking light attached to a warning sign along the road. The success of this system can be measured by the positive public feedback, the increased use of these roads by bicyclists, and, most importantly, by the reduction of accidents.
A future RITS goal is to detect pedestrian movement on rural roads and provide motorists with advanced warning through a synchronized VMS system.
Across the rural sections of Colorado, CDOT broadcasts information about weather and traffic conditions on AM 530, using a series of transmitter towers and repeater sites. The system effectively provides immediate site specific weather information. In addition, announcements can be programmed for road closures, traveler forecasts, and changing traffic conditions.
Spring and summer rain storms in rural sections of Colorado often create flash flood conditions. To warn motorists when roads are likely to be under water, CDOT uses stream gauges to detect rising water levels and activate a VMS. This proactive high-water warning system has greatly reduced vehicular accidents at several critical channel crossings across Colorado.
Steep mountain grades present problems for commercial vehicle operators. Several attempts to communicate these dangers to commercial vehicle drivers have been made.
Applications such as static warning signs, truck speed limits, and educational videos at state weigh stations have all been used to minimize this condition. The Dynamic Downhill Truck Speed Warning System (DDTSWS), developed in 1995, provides specific information to individual truckers before they enter the steep grade sections. The first DDTSWS was placed west of the Eisenhower Tunnel in the westbound lanes of I-70. DDTSWS uses inductive loops, WIM technology, and a VMS. First, the trafAc loop detectors trigger the system. Then, WIM determines the truck weight, speed, and axle configuration. Finally, an algorithm within the computer system computes a safe speed based on this information and alerts the driver through a VMS. Since its deployment, truck-related accidents have declined on these 6-percent and 7-percent grade sections even while the volume of truck trafAc has increased by an average of 5 percent annually. Currently, British Columbia, Oregon, and West Virginia are designing and constructing similar systems.
|Linking speed detection radar and variable message signs, CDOT is able to warn drivers who are exceeding the speed limit to slow down.|
Looking Toward the Future
The RITS program in Colorado continues to show results as user services are being more widely used and as leveraging of state and federal funds increases. Colorado transportation stakeholders are beginning to recognize the operational benefits of smart rural highways and the value of continued RITS research and development. Nevertheless, the increased budget constraints on RITS modernization have forced CDOT to evaluate more cost-effective approaches for expansion. Current deployment strategies compare future program goals and public needs against available funding resources. CDOT is also evaluating affordable RITS initiatives against the complex and ever-changing public needs to determine to what extent the expected benefits are achievable. CDOT's RITS goal is to encourage and develop advanced technological systems that create a future with safer and better informed travelers, improved traffic control systems, and more efficient commercial vehicle operations.
Michael Kulbacki is an operations and maintenance engineer for the Colorado Division of the Federal Highway Administration. He received a bachelor's degree in civil engineering from Virginia Tech, and he is currently pursuing a master's degree in environmental engineering at the University of Colorado.