Summary

The Caltrans freeway loop detector system provides valuable data for traffic operations, performance measurement, planning, and traveler information. Its 8,000 vehicle detector stations (VDS), encompassing 26,000 loops, are worth an approximate 320 million dollars but are not well maintained. Only 60 percent of the loops are considered "good" and vary in their quality by district anywhere from 50 to 90 percent.

This proposal seeks to understand what can be done to improve the health of the system. Questions to be addressed include: are the failure rates in loops among districts different? Are repair rates different? Are loops better installed in some districts or on some freeways than others? How much additional resources are needed to make 95 percent of loops "good?"

By formulating and estimating statistical models for the loop detector life cycle, using a daily summary of loop detector health from PeMS, this study can produce results that can be combined with Caltrans' cost of installation and repair to design a good detector of the health of the loop detector system.

Related PATH Articles/Journals

Ram Rajagopal and Pravin Varaiya, "Health of California's Loop Detector System" (UCB-ITS-PRR-2007-13). 01 August 2007.