Note: I was poised to post this Friday, July 21 in the morning. But the news that Devil’s Slide would reopen August 4th preempted the posting and relieved some of my frustration. However, I’d still like to understand the variability of sensor readings to actual timed experience.

Start original blog entry: While I applaud CalTrans for instrumenting the roads and giving helpful clues to commuters about travel times from point A to point B, the accuracy reflected in these clues leaves something to be desired.

Thursday afternoon the 511.org web site and the sign onsite for highway 92W indicated that it was 33 minutes travel time from I280 to Highway 1 on 92W. In reality, it took 18 minutes to move from the sign through the traffic light at 35N and 92W, 0.75 miles. The time for this travel segment, a 7 mile trip over the hill from I280 to Highway 1? 46 minutes.

CalTrans, clearly you’ve instrumented the road. Why the heck aren’t you reading what you collect from the sensors and reflecting it accurately? Bad information is worse than no information. 39% error in travel time is a bit high when actual data is available.

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