Niles Canyon Road Is Safer Than Average

Caltrans wants to spend $75.9 million on a “safety” project to widen Niles Canyon Road, even though data indicates that the road is already safer than average.  To make its case, Caltrans is presenting misleading arguments to the public.
The underpinning for Caltrans’ argument to widen Niles Canyon Road is that the road is not safe.  At every public meeting they’ve held, they trot out the same old chart, with the cumulative total number of accidents for over a decade.  They then leave the slide up during Q&A.  Those of us who have spent time analyzing the safety data, take exception to Caltrans method of reporting the data, which appears designed to provoke a visceral and fearful reaction, instead of presenting facts that would lead to a measured and thoughtful response.

The truth is that data shows Niles Canyon Road has been safer than average since at least 2005; however Caltrans manipulates the data to disguise this trend.
In the Phase II DEIR, Caltrans states that “although the accident rate within the project area is below the state average, the number of fatalities has been higher than the statewide average” (p. 1-1).  To make its case,  Caltrans utilizes “Three-year[s of] safety and traffic accident data from January 1, 2002 to December 31, 2004” (p. 1-2).  In a small box the DEIR notes there were two fatalities in this 3-year period.  Caltrans does not mention (as noted on p. 13 of Caltrans’ Phase I Negative Declaration) that from October 1, 2000 to September 30, 2003 there were zero fatalities.  Nor does it mention that in the 5 years subsequent to its 3-year sample, there was one fatality (Caltrans does not provide this last statistic in any of its documentation — the data is from the CHP).  If you want to talk about averages, there is a huge difference between zero in three years, to two in three years (Caltrans’ safety sample), to one in five years.

By focusing on the total number of collisions for a decade in its presentations to the public, Caltrans is able to disguise the fact that the accident rate within the project area is below the state average.  Focusing on the total number of collisions for a decade also ensures that the downward trend that has been in place since various safety measures (including the double row of Botts’ dots with rumble strip median installed in August 2007), is never identified.

State Wide Integrated Traffic Records System (SWITRS) data from the California Highway Patrol indicates Niles Canyon Road today is considerably safer than Caltrans’ safety sample would lead the public to believe.
Caltrans focuses on the three-year period of 2002-2005 (in which there were 58 accidents), to make its argument.  According to the most recent three-year-period for which SWITRS data is available (namely, 2007-2009), there were only 38 collisions.  This is a 34% decrease in accidents since Caltrans’ safety sample.

SWITRS data also tells us that there was one fatality from 2005 to 2009.  This means that the road not only has fewer accidents than the statewide average, but the likelihood of being in a fatality has dropped precipitously (from two fatalities in a three year period, to one fatality in a five year period).

For those of you interested in the one fatality, the Federal Highway Traffic Safety Administration (FHTSA) has information about Alameda County that includes a map (hint:  type “Niles Canyon Road” into the search bar) indicating where the fatality occurred; when (a weekend afternoon in December 2007); and that it involved a lone motorcyclist with a positive blood alcohol level.  No other vehicle was involved.

Run the numbers yourself.
Those of you who like to do independent research are encouraged to go through the raw data.  The CHP’s SWITRS website can be found here: You will need to create an account to get access. Once you are able to log in you can then use the Raw Data option in the left menu panel to download the records you want.

Your chance of getting into an accident on Niles Canyon Road is minuscule.
Caltrans has been requested to provide data on when safety improvements that are already in place were installed, but unfortunately they have not complied (we do know that the double row of Botts’ dots with rumble strip median were installed in August 2007).  Caltrans has also been asked to provide data on how many vehicles traverse the canyon each day, and the likelihood of being in an accident — again Caltrans has not complied.  We did, however, find data on the traffic volume through the canyon from 2007 through 2009, and by also using the SWITRS data can safely assert that despite Caltrans’ scary numbers, the likelihood an individual motorist will get into an accident in Niles Canyon is extremely low:

  • In 2007 there were approximately 10,402,500 trips through the canyon and 16 accidents.  Only 0.0000015% of all trips through the canyon that year resulted in an accident.
  • In 2008, there were approximately 10,183,500 trips through the canyon and 13 accidents.  Only 0.0000013% of all trips through the canyon that year resulted in an accident.
  • In 2009, there were approximately 10,767,500 trips through the canyon and 9 accidents.  Only 0.0000008% of all trips through the canyon that year resulted in an accident.

“Lies, damned lies, and statistics” — Mark Twain
Based on the data we currently have, Caltrans wants to spend $75.9 million taxpayer dollars to make a road that is already safer than average, “safe”.   Whether safety will be improved by building a bigger, faster road that can accommodate larger trucks is questionable, especially since a third of all current accidents in the canyon involve speeding and another third involve trucks; but that’s a different post for a different day.  In a time when deep cuts are being made to government programs and services for our neediest and most vulnerable residents, think of the good that money could do elsewhere.

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