Traffic surveys

[pfish]

This mainly applies to city streets, but I thought someone might know..

I know there has to be a traffic survey done on a section of a road before an officer can use radar. How long are these traffic surveys valid for? I'm looking at a traffic survey dated 9/19/1996. Would this be a speed trap due to the outdated traffic survey?

Any comments welcome!

[TheForceCHP]

might i ask if this question is in regards to a ticket that you might have gotten. any info. would be helpful;)

[Tom]

I'll answer ticket or not. There are some roads that require it and some that do not. You really have not posted enough info info so I'll give you the BASIC (there are MANY variables) answer and it is 10 years. Sorry.

Tom

Ohhh - Go to Vehicle Code Section 40802 - Answers everything.

[Mac]

...There are some roads that require it and some that do not...
Yep - school zones and "local roads" (by definition) being amongst those that do not.

...Ooops, hope that didn't blow your impending quiz question! :biggrin:

[pupdog]

I don't get it...if the speed is posted, that's the speed. Why would it be different just because of how long ago the state had a chance to survey it? If the speed limit was higher, it would be posted as higher. I thought surveys were to determine if more controls such as stop signs or lights are needed. But what do I know, I'm still an applicant.

[SB 405]

Unfortunately many times it takes a series of accidents before local cities do anything about unsafe conditions.

[Tom]

Why would it be different just because of how long ago the state had a chance to survey it?

Ahhh, if it could only be so easy...then of course a lot of lawyers would be out of jobs......

Surveys, per se, are used for what you describe as well. Speed surveys are used to determine the 85th percentile of the speeds on the roadway. Basically this is just long and boring jargon of how we, as Officers that use radar for speed, don't unneccesarily (as a department or Agency) lower the speeds on a roadway to gain revenue. Confused yet? It is.

Other things are taken into account as well (collisions, pedestrians, cyclists) then the Traffic Engineer of the jurisdiction submits his recommendation to the courts and us as well. It's a series of checks and balances to protect the motoring public from lacivious departments hell bent on revenue.

Tom

[bcjack]

Speed surveys, as they are done now, kind of reward the speededs. The speed limit is generally set at what 85 percent of the surveyed cars are traveling at. I have a residential street near my house that was surveyed at 47 mph (85th percentile speed was 47). This is a 4-lane arterial with single family homes on both sides of the street, and two "Safe Routes to School" pathways. the survey isn't always the appropriate speed!!! As a side note, I used to work radar on that street as a Reserve Officer (1995 and back) and consistently got 55 to 65 mph pinches.:badgrin:

[dw]

...There are some roads that require it and some that do not...
Yep - school zones and "local roads" (by definition) being amongst those that do not.

...Ooops, hope that didn't blow your impending quiz question! :biggrin:

Also, maximum speed limits (55, 65, & 70) do not require a survey.

[Mac]

In a nutshell, the main purpose of speed surveys are to keep counties/municipalities from setting artificially low speed limits just for purposes of revenue from traffic enforcement. Otherwise, it would be easy to set a 25 mph speed limit on a six-lane main roadway, and then just let the traffic cops enforce the heck out of it when everybody's doing a (reasonable and prudent) 45 or 50 mph on that roadway. Using the 85th percentile ensures that prima facie speed limits are appropriate and reasonable for the roadway being surveyed.

[pupdog]

Last night while I was out for a run, I noticed something that made me think of this. I was in an office park area, the sort with short, curvy roads (typical). The speed limit is 25. And I noticed that the center line was of the passing sort. Made me wonder...if it's 25 mph, why is it all passing lane? You'd have to speed! And why are curvy roads painted with passing lanes? It just didn't seem that well thought out. I suppose that's among the many such mysteries of the roads.

[NWTSCL]

By "office park area", do you mean that it is private property? That may give you a clue.

I am definitely not a traffic engineer, but Caltrans' Traffic Manual may help you out. (If it is transportation or work-related, Caltrans wrote a book about it.)

Traffic Manual (http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp/supplement.htm#3) Click on Ch. 6 - Markings, then Part 3: Markings, Chapter 3B: Pavement and Curb Markings

WARNING! Be prepared to be bored out of your mind!

[dw]

Last night while I was out for a run, I noticed something that made me think of this. I was in an office park area, the sort with short, curvy roads (typical). The speed limit is 25. And I noticed that the center line was of the passing sort. Made me wonder...if it's 25 mph, why is it all passing lane? You'd have to speed! And why are curvy roads painted with passing lanes? It just didn't seem that well thought out. I suppose that's among the many such mysteries of the roads.

That argument can be made for most areas where passing is permitted. The assumption is all traffic may not be going the limit. You may go 25 miles per hour to pass someone going 15, for example.