Technical Assistance Brief
Brief #7
August 1994
Background
The impetus for AVL/MMS occurred in 1989 when RTD conducted a cost/benefit study of improved communications systems alternatives. Their existing radio system had severe limitations with respect to radio frequency coverage, functions and features, data transmission capability, and expansion capability, and was a substantial financial burden to maintain in operable condition. The study recommended increased radio channels, microwave equipment replacement, new bus radios, greater data transmission capacity, and emergency, farebox, and mechanical alarms, as well as the addition of automatic vehicle location and schedule adherence monitoring functions.
With the help of a consulting firm, RTD developed the requirements for the new communications system. RTD was able to take advantage of the substantial advances in the communications and information fields that had occurred since the 1989 communications study to obtain the latest in Computer Assisted Dispatching (CAD) and AVL technology.
Objectives
RTD's major objectives in implementing the AVL/MMS are:
o to improve the ability of dispatchers to adjust on-street operations
o to provide accurate and real-time information to the riding public
o to increase safety through better emergency management
o to develop more efficient schedules
System Description
RTD provides public transit services to six counties in the Denver region, covering an area of about 2,300 square miles. RTD operates more than 800 buses. The first segment of their light rail line is expected to begin operation in October.
The heart of the new communications system is the Operations Center where fleet activity is controlled. The Operations Center is equipped with state-of-the-art dispatch consoles and computer work stations. The CAD feature gives the dispatcher greatly improved awareness of what is happening on the street and the ability to take quick action to rectify service anomalies. The MMS receives location and schedule adherence information from each vehicle. The vehicle is displayed on a computer monitor as an icon overlaid on a map of the Denver area. Each icon is color-coded to indicate the degree of schedule adherence of the bus. Vehicle location is updated on the dispatcherÕs monitor every two minutes under normal conditions. Other route, schedule, and incident data are reported to the dispatchers on an exception basis and displayed on a separate monitor.
Each RTD vehicle is equipped with an integrated radio/AVL package which consists of a conventional mobile radio, an onboard processor, a driver interface, and a GPS antenna. The vehicle odometer is connected to the onboard processor to provide movement/distance data to the system for the dead-reckoning feature which supplements the satellite information in areas where satellite signals cannot be reliably received.
The onboard processor receives the GPS information, calculates the vehicleÕs position, and compares that position to the schedule. The vehicle position and schedule adherence information is transmitted routinely to the Operations Center during the regular reporting sequence. Exceptions or incidents are transmitted immediately. The onboard processor also serves as an interface and distribution center to control the radio, switch signals from voice to data, and send/receive signals to/from various input/output devices such as the driver console, handset, external microphone, and public address system.
The driver console (called the Transit Control Head) allows the driver to communicate with the dispatcher or send various pre-set messages. In case of an emergency, the driver can activate a silent alarm switch to alert the dispatcher. The dispatcher can then activate a covert microphone located on the bus to monitor the emergency situation. At the same time, the onboard processor will report the bus position at a more frequent interval to allow more accurate tracking of the vehicle in distress.
The system uses nine radio channels, two for data and seven for voice. Transmitters are located at three different sites in the Denver metropolitan area. The CAD system selects the site and the available channel for best reception and channel utilization.
Information generated from the system will be used to generate reports for use in evaluating transit system performance and providing data for operational and policy decision-making. Real-time information determined through the AVL/MMS will be used to update the arrival/departure time information displayed on signboards at the two downtown transit terminals. It will also be channeled to RTDÕs Telephone Information Center (TIC) for use by the operators in providing real-time information to customers. A new trip itinerary planning system will provide alternative travel routes for transit users. In addition, as part of another IVHS operational test, information kiosks providing real-time transit information will be installed at the new Denver International Airport and selected bus terminals and park-and-ride lots.
System Benefits
RTD anticipates that the new AVL/MMS will have the following benefits:
o Substantial labor savings and a reduction in some manpower requirements will be achieved. For example, automated data collection will reduce the labor and cost expended in the collection and analysis of data for scheduling and reporting purposes and manual traffic checkers will no longer be required.
o The street supervisors can be more effectively utilized.
o Data will be available much sooner for management decision-making.
o More efficient scheduling will result in reduced deadhead and in-route hours.
o Schedule development will be accomplished quicker.
o The automated database will contain daily performance reports from all buses on all routes (compared to the current average of one ride check per route per year). This will provide more accurate running time information and allow scheduling staff to better match schedules to demand, thereby making more efficient use of the buses.
o The new radio system will provide improvements in coverage and channel allocation. It will allow data communications which will reduce the amount of voice communications and make more efficient use of the channels.
o The silent alarm and AVL features will permit rapid identification and location of an on-board emergency and a reduction in emergency response time.
o The schedule improvements and enhanced safety should increase the quality of service, resulting in greater passenger satisfaction and an increase in ridership.
o A more efficient and smoothly running system will elicit fewer passenger complaints, leading to a more pleasant work environment, especially for drivers and telephone operators.
Evaluation
A comprehensive evaluation of RTD's AVL/MMS is being conducted for FTA by the Volpe National Transportation Systems Center, utilizing the contractor team of Battelle/Castle Rock Consultants. The evaluation will measure the degree to which the objectives of FTA's APTS Program and those of RTD are achieved.
Several categories of measures will be used to assess the success of the project. Among the major evaluation measures are:
o initial costs of hardware, software, planning, implementation, and training
o ongoing costs of operations, training, and maintenance
o accuracy of vehicle position determination
o response time to emergency situations
o customer information service time
o schedule adherence changes
o service utilization and productivity
o perceptions of the public towards service, travel time, schedule adherence, and safety
o attitudes of the employees towards ease of use, data quality and reliability, AVL reliability, ease of hardware repair, and ease of hardware and software modification
o human factor considerations
o organizational relationships and changes
Additionally, external factors which may influence project results will be monitored and taken into account in the final report discussion.
Status
All of the fixed equipment - radio transmitters/receivers, microwave links, AVL/MMS controllers, dispatch consoles, computers, etc. - has been installed. However, as of July 1994, due to difficulties experienced with the integration process, only about 600 buses and a few support vehicles were operational with basic AVL/MMS functions and were being tracked by the system for testing purposes.
Hardware, software, and system integration problems have caused delays in implementation and final acceptance of the system. Most of these have been corrected and the few remaining are being addressed. Software development and system integration especially have required more time and effort than expected. The principal items left to be resolved are the Route Schedule Adherence (RSA) feature and some radio communications difficulties. The RSA is being tested on three routes.
The next software version is due to be installed in October 1994. If this version successfully corrects the remaining problems, full implementation could occur by the end of 1994. A future brief will describe the results of this operational test. For more information on the RTD AVL/MMS project, contact Lou Ha of RTD, at (303) 299-6265.
There are a variety of local initiatives and APTS operational tests being evaluated across the U.S. The evaluations cover all three focus areas of the APTS Program: Smart Traveler technology, Smart Vehicle technology, and Smart Intermodal Systems. For more information contact FTA's Advanced Public Transportation Systems Division at (202) 366-0080.