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Driving by the numbers

Charles Smith Berkeley
Wednesday January 16, 2002


Numbering highway exits has been the subject of some controversy inside Caltrans for many years. I suggested it in 1960 when the new governor Pat Brown set up a six-month Work Improvement Program for all state employees. (In 1959, Daniel Patrick Moynihan, with the assistance of Ralph Nader, had written an article for The Reporter magazine titled "Epidemic on the Highways" which discussed how one of the low-priced three (Ford, Chevrolet, and Plymouth) had an accident rate double the others.) 

The biggest problem was integrating the post mile system in with the numbers of exists. Post miles are used to locate all items on highways within each county right down to the 1/000th of a mile, with notations painted on most bridge markers, culvert delineator, etc (This was long before computers.) 

Post mile markers are used in many ways. All accidents on highways are reviewed to see if there is a cluster of accidents that might indicate a highway defect which might contribute to accidents at a specific location. 

The $40 million estimate for exit numbers is nothing compared to the vast amounts that Caltrans has spent on sign bridges at hundreds of interchanges, with many bridges stretching all the way across wide freeways and costing as much as $100,000 each. 

The monthly wage costs of a whole staff of signing engineers in each of the 12 Caltrans Districts and of the cost of making the big signs, transportation to the sites, erecting them, often in the middle of the night, also needs to be considered among the savings with numbering exits. 

The accident costs of the confusion from named exits is no small consideration. Up until the late 1960s the CHP published an annual Statistical Bulletin which showed details. The accident rate of out-of-state drivers was very high, especially with truck drivers. Names are hard to remember, compared to numbers. 


Charles Smith