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39 4.8 Mapping to find relationships to fuel consumption, brake wear, or engine maintenance needs. Another suggested measure of mechani- Equipped vehicles can serve as GPS probes whose archived cal demand that could be determined from interstop AVL AVL data is used to improve a transit agency's base map. For records is the number of acceleration/deceleration cycles. example, if buses stop often at a location not indicated on the base map as a stop, then a stop may be missing on the base map (perhaps because it has been informally added by oper- 4.9.3 Terminal Movements ators); this data can be used to help locate both permanent Interstop GPS records might be used to analyze vehicle and temporary stops. movements at terminals, which may be of interest at busy A more explicit use of buses as GPS probes is to intention- terminals with capacity, safety, or efficiency issues. A better ally use them to map a bus's path through a new shopping understanding of terminal movements can also lead to better center or subdivision. For this application, the on-board com- determination of arrival and departure times, which are crit- puter has to be set to make frequent interstop records. An ical for schedule analysis. Israeli APC supplier includes a learning mode that allows an on-board surveyor, seated beside the operator and holding a laptop computer, to create geocoded records with codes and 4.9.4 Control Messages comments at points of interest (e.g., where a bus makes a While operator-initiated messages (e.g., indicating pass- turn) to help map the bus's path. ups or bicycle use) are customarily coded in a manner that permits numerical analysis, control messages sent by radio to bus operators are not customarily so coded. To the extent they 4.9 Miscellaneous could be coded for common commands such as hold for the Operations Analyses schedule or hold for a connection, they would allow one to The availability of archived AVL-APC data creates oppor- analyze where and when those control messages are used, tunities for analysis of many other aspects of operations, of account for their impact on running time, and analyze their which five are listed in Table 4 and discussed in this section. effectiveness. Other analysis opportunities will undoubtedly be discovered, highlighting the need for AVL-APC databases to support 4.9.5 Operator Performance exploratory and new analyses. Finally, published (28) and unpublished studies by Tri- Met using AVL-APC data indicate that much of the variance 4.9.1 Acceleration and Ride Smoothness in running time and schedule adherence can be explained by One aspect of service quality that might be measured with operator behavior. An analysis of performance by operator an advanced AVL system is the smoothness of the ride. Pas- could be a valuable tool for training operators and for exper- sengers value a smooth ride, without jerky accelerations or imenting with different methods of supervision and con- decelerations, while avoiding unsafe speeds. At present, tran- trol. To account for the bus bunching phenomenon, an sit agencies in Paris and Brussels use externally contracted operator's performance on short-headway routes should surveyors called "mystery shoppers" to rate quality of service account for the position of its leader. Performance elements in several categories, including ride smoothness; their ratings can include schedule deviation (especially at dispatch), run- are, of course, subjective. Very frequent records of speed ning time, layover time, headway maintenance and bunch- would permit an objective measurement of linear speed, ing, and more. acceleration, and deceleration; swerving and bouncing also Correlations between data items may reveal interesting could be measured if accelerometers in three directions were operating patterns. Do operators that are beginning to run integrated into the system. early intentionally slow down, and do operators that are getting behind speed up? Do operators drive differently when they have a heavy load or after they depart the terminal late? Being 4.9.2 Mechanical Demand able to identify individual operators may reveal operator- AVL data may permit analysts to estimate mechanical specific patterns or relationships between running time and demands on buses in order to relate them to vehicle perfor- operator experience (both overall and on the specific route). mance and maintenance. For example, combining measure- Uncovering operating patterns like this can be useful for plan- ments of vehicle acceleration and passenger load with GIS ning both schedules and methods of supervision and training. information on roadway grade allows estimation of the trac- Operator performance must be analyzed with careful respect tive and braking forces required, which then could be analyzed for operator acceptance and safety. If used for discipline, data