The objectives of implementing an AVL system for the Denver Regional Transportation District (RTD) included developing more efficient schedules, improving the ability of dispatchers to adjust on-street operations, and increasing safety through better emergency management.

In conjunction with the new AVL system, the entire dispatcher-to-field communications system was replaced. The new communications system is significantly more advanced and provides more capacity than the old system.

This study attempted to evaluated AVL and isolate the impacts of an improved communication system.

Since AVL was implemented, the transit system has improved quality service. Between 1992 and 1997, RTD decreased the number of vehicles that arrived at stops early by 12 percent, decreased the number of passengers per vehicle that arrived at stops late by 21 percent, and decreased the number of customer complaints by 26 percent (per 100,000 boardings). In part, these inprovements were the result of improved schedule adherence.

The AVL system helped achieve the third objective, improved safety, for both operators and passengers through the use of an on-board silent alarm. Operators reported that they felt safer now than prior to AVL implementation. Passenger assaults per 100,000 passengers decreased by 33 percent between 1992 and 1997. There were also many reports of criminal acts thwarted because police responded quickly with accurate information from AVL system. Misuse of the silent alarm is a continuing problem. Additional training is constantly performed by RTD, and the operations department indicated that the number of silent alarm misuses has decreased as a result. However, operators cited that the on-board location of the emergency button makes it easy to accidentally bump.

The AVL system proved to be highly accurate at determining positions. In 304 tests of the system, the system was within the acceptable threshold 292 times. The thresholds ranged from 100 to 300 feet, depending on the location of the test. These results are detailed in Tables 4.3.2. This is a success rate of more than 96 percent. RTD experienced a 23 percent decrease in lost service hours in part due to improved radio reliability. The decrease in service delays that resulted from higher system reliability meant improved service to customers because more vehicles were available for service.

The GPS based vehicle location function rated very well with dispatchers. Operators and dispatchers are able to communicate more quickly and efficiently. More than 80 percent of the dispatchers found the system "easy" or "very easy" to use, while more than 50 percent of operators, and street supervisors felt likewise.

Where the AVL system provide dispatchers with more information and is a tool that allows them to better monitor the vehicle fleet, many operators perceived it as an intrusion or a way for RTD to control them. Operators are penalized for not adhering to their schedules and have expressed a particular desire to have the schedule adherence function help them to make adjustments throughout their route.

RTD operations personnel indicated that they do not expect the AVL system to provide noticeable economic impacts. Their reasons for selecting the system were to give them better control over a growing fleet, and to provide better customer service in order to retain customers and attract new ones.

Passengers and Operator Assaults.

	1992	1993	1994	1995	1996	1997
Passenger and Operator Assaults	105	102	101	88	122	84
Change from Previous Year		-2.9%	-1.0%	-12.9%	38.6%	-30.3%
Passenger and Operator Assaults per 100,000 Boardings	0.18	0.17	0.16	0.13	0.17	0.12
Change from Previous Year		-5.6%	-5.9%	-18.8%	30.8%	-35.3%

Notes

For additional information pertaining to the impacts of CAD/AVL on RTD transit operations see the corresponding report:

Denver RTDS Computer-Aided Dispatch/Automated Vehicle Location Systems - The Human Factors Consequences (September 1999).