1991-10-01

Pathfinder Status and Implementation Experience 912784

The paper will include a brief overview of the Pathfinder system which has been installed in Los Angeles. The system is undergoing evaluation at this time. Some implementation experiences will be included. For example, the paper will discuss some of the reasons for the changes from the presentation of congestion information in synthesized voice to all digital voice. The Pathfinder experience with mixtures of digital and synthesized speech led to confusion, which can be avoided in other systems. The time taken for message presentation was excessive and led to a necessary reduction in the number of messages presented when the voice mode is selected by the driver. This significant limitation could alter the design of other systems which might rely on speech as a presentation mode to the driver. Also, will be included the experiences encountered in the presentation of congestion symbols on the in-vehicle map display which will allow the display to function as it was originally designed by the manufacturer. One of the problems associated with superimposing symbols on a map is that as the driver “zooms” in, the symbols move away from the road. The map scaling factors must be adjusted. The design location of the symbol needs to convey both direction and intensity of the congested link. In addition, there will be a discussion on the communications testing and installation issues. The Pathfinder base station communication system involves a phone line from the control center to a communication hut owned by the city of Los Angeles. A conduit exists from the hut which is owned by the county. This conduit is terminated in another hut which is owned by the California Highway Patrol (CHP). The communication line goes from the hut to a tower where the antenna is mounted. The tower is owned by the CHP. In addition the transmitter in the hut had to be shock mounted for earthquakes. The paper concludes with a brief status of Pathfinder and considerations used for the design of the system.

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