-Tom in Montana

http://www.howwedrive.com/2009/06/22/a-speed-nudge/#comment-7872

Of all their “effectiveness studies”, only one actually mention changes in accident rates. It also suggests that their efforts aren’t responsible for the improvements.

Memorandum

Date: February 2, 2007

To: Humboldt Area

From: DEPARTMENT OF CALIFORNIA HIGHWAY PATROL
Humboldt Area

File No.: 125.11998

Subject: REDUCTION OF COLLISIONS ASSOCIATED WITH ROADWAY CHANGES IN THREE AREAS OF HUMBOLDT COUNT

In 2006, there was a significant reduction of collisions at three locations in the Humboldt Area. The reduction of collisions was associated with engineering changes made by the California Department of Transportation (Cal Trans). These changes include changing the roadway surface from conventional asphalt/concrete pavement to “opengrade” asphalt/concrete pavement and posting additional sings, some of which are radar activated signs that indicate the speed of approaching motorists. Two of these areas are located on US 101; the third area is located on SR-299.

The north most area is located on US 101, between mile post markers 101 HUM 124.71 and 125.98; a stretch of highway frequently referred to as “the curves just south of the by-pass, north of the old fish hatchery.” In 2004, there were nine reported collisions in this area. In 2005, there were eight reported collisions in this area. Cal Trans completed a safety project, which included a change to “Open Grade” roadway safety surface, and the addition of radar activated signs in December 2005. In 2006, there were 5 reported collisions in this area.

The second area on US 101 is located between milepost markers 101 HUM 109.42 and 112.53; an area commonly called “the Big Lagoon Curves.” In 2004, there were 12 reported collisions in this area. In 2005, there were also 12 reported collisions in this area. Cal Trans completed a safety project in this area that included radar activated signs and a change to “open grade” roadway surface in December of 2005. In 2006, there were 5 reported collisions in this area.

The third area is located on SR-299 on the east slope of Lord Ellis Summit, between milepost markers 299 HUM 19.05 and 20.67. Though the curves are not as tight as those on US 101 are, the roadway grade is steep. Both in 2004 and 2005 there were 12 reported collisions in this area. Though no comprehensive safety project was conducted in this area, Cal Trans conducted a number of incidental improvements and repairs. This area does not have radar activated signs. In 2006 there were three reported collisions in this area.

Changing key spots to “Open Grade” material in 2006 in CA reduced accidents from 12 annually to 3-5.

I now think this explains a lot of crime – “what did they think would happen?” is answered by “they didn’t think at all…”

I conjecture that this explains part of drunk driving. People don’t plan to get “drunk”, don’t plan to drive drunk, and when drunk have poor judgement about their driving. So all sorts of “don’t drive drunk warnings” may have no effect because they don’t intend to do it, perhaps don’t think they are doing it, or only realize it when they’re already in route. (Are there studies or other data on this?)

The human factors are nearly always significant, even if it’s just an inability to recognise that the road engineering is inadequate/dangerous/faulty.