Lessons Learned From a Pilot Project of an Automatic Vehicle Location System in an Urban Winter Maintenance Operations Setting
The Virginia Department of Transportation (VDOT) maintains all interstate, primary, and secondary roads in 93 of Virginia's 95 counties. Snow removal and ice control activities are of special concern in urban counties since they slow traffic on an already congested highway system and adversely affect a large part of the population.
VDOT instituted a pilot automatic vehicle location (AVL) system to attempt to improve the management of operations and communications during emergencies. AVL is a technology that locates vehicles using a global positioning system (GPS), monitors vehicle activity, transmits vehicle location and activity information to a remote site, and displays the information on geo-referenced maps. As part of the pilot project, VDOT installed GPS units in 80 trucks. The pilot project extended over three winters, from 1997 through 2000.
The purpose of the project was to evaluate the AVL system's effect on (1) the administration of snow removal and ice control contract forces, (2) the provision of information concerning road conditions, and (3) the management of snow removal and ice control activities. The system tracked vehicles to an acceptable degree of accuracy. However, due to operational and institutional issues, system problems, and mild winters during the study, no financially quantifiable savings could be determined.
When deploying a new system, it is important to envision the operation of the device in the environment where it will be used. Designers should take into consideration the end-users; the conditions in which the device will be used; and the condition of the physical environment in which the device will be used, such as temperature, humidity, and dimensional restrictions.
- Consider the physical environment in which the system will be used: Snow removal activities represent the worst-case environment for testing AVL technology, such as that used in this pilot program. In snow events, temperature and climatic conditions are at their worst. GPS signals undergo serious electronic signal attenuation and noise effects because of snow on trees and emissions from vehicle radios and strobe lights. Vehicle-mounted units are subject to significant corrosion, mechanical shock, and fatigue conditions. Although all of these conditions did affect system performance, they did not preclude successful use of the technology over three winters of use.
- Focus on the design restrictions: Along with the harsh winter environment, the repetitive installation and removal of in-vehicle GPS tracking receiver and communication devices (referred to as in-vehicle units or IVUs) also resulted in a higher than expected failure rate (5 percent to 10 percent per storm) for wiring and sensor units. The unsecured units (those without a mounting board) moved around in vehicles during operations, resulting in the connecting plugs frequently being disconnected from the back of the IVU, wire breaks, display screen fractures, and antenna lead separations. The lesson learned was that since temporary installation of IVUs created problems, IVUs should be permanently installed in vehicles when possible.
As learned from this experience, system designers should take one more step in their design process and design devices so that the devices will work properly in the environment where they will be used. Additionally, assumptions that designers have made and used in the past may not always fit for devices that will be used in different environments; designing devices to fit the needs of their intended environment could lead to increased system productivity and efficiency, and increased customer satisfaction by all who work with the systems.