It has been widely accepted for decades that, in terms of safety, the proper procedure is to follow the “85th percentile” rule — the speed limit should be set at the speed where 85% of the vehicles are at or under the speed limit.

Most people automatically drive at SAFE speeds, at speeds that they are comfortable with for the driving conditions that they observe. Unfortunately, many governmental bodies have — mistakenly — believed that lowering speed limits leads to safer driving, when, in fact, the opposite is often true. Consistency of speed is a prime factor in road safety and setting speed limits too low means that there will be far more passing movements — due to the small number of people who actually follow the speed limits — and having too wide a range of vehicle speeds on the same road is a detriment to safety. There are many documented cases where an increase in posted speed limits has led to REDUCTIONS in collisions, injuries, and fatalities.

There are, of course, a number of factors that have to be taken into account before simply doing a speed survey and using the results to post the speed limit. The speed limits must be understood to be applicable to properly maintained roads when there are not adverse weather conditions, such as rain, snow, ice, or fog. During peak hours and other heavy use periods, congestion will often make exceeding — or even reaching — the speed limit a practical impossibility.

Other factors that should be considered — as Umberto Brayj points out above — are line of sight limitations, the number of vehicles entering and leaving the road and the number of entry/exit points, pedestrian traffic, and land use along the road. The way that this process should work is that the speed survey is the starting point, but that qualified and experienced transportation engineers (or others that have demonstrated their competence in this area) review the other factors and make professional judgements.

The law is set up for that process to occur. However, the local governments must make effective efforts to comply with the spirit of the law, which begins with having a well-staffed, well-qualified department to perform the necessary work. This is often difficult, particularly in times, like now, of fiscal shortfalls.

I am not familar with the specific conditions for all the roads being discussed above. While I can name any number of streets, roads, and freeways where my own experience tells me that the speed limits are set unsafely LOW, the conditions that are described appear to provide sufficient arguments to convince me that a qualified expert should review the facts, including spending time on-site, prior to any speed limit increases in those particulars.

From my own long experience, both as someone who has been in the surface transportation business for over three decades, spending a fair amount of that time on safety matters, and someone who has been driving for over four decades, if you want to get people to obey the speed limits, properly setting speed limits is, absolutely, the first step. People will simply ignore the speed limits when they are set too low, regardless of the amount of enforcement — so, unless the purpose of enforcement is to generate revenue to balance the government budget, the superior use of scarce sworn law enforcement traffi safety assets is NOT speed enforcement (with the very obviouis exception of those who are above the 85th percentile and/or otherwise driving unsafely), but concentrating on REAL safety issues — which, interestingly enough, should include those who are driving unsafely SLOW.

To give you an idea of how far out of line some California speed limits are, I often drive between the Bay Area and SoCal on I-5 trhough the Central Valley, where the speed limit is posted at 70 mph, and I drive my vehicle at a calibrated 70 mph — and count the times I am passed and that I pass. I have yet to find that my 70 mph speed is even in the tenth percentile; indeed it is not uncommon to drive for more than an hour at 70 mph without passing another car. Does it appear reasonable to conclude that 90+% percent of the auto drivers are driving so unsafely that they should be ticketed?

Let’s set the speed limits where they should be set to maximize public safety for all who are using the road — including truckers, cyclists, and pedestrians — AND properly reflecting the conditions for each specific road.

Perhaps properly setting speed limits, and other traffic regulations, will actually lead to people respecting the laws as wise and proper, rather than as something that is so far out of reality as to be ignored as a matter of course.

“When qualifying an appropriate speed limit, local authorities may also consider all of the following findings:
1. Residential density, if any of the following conditions exist on the particular portion of highway and the property contiguous thereto, other than a business district:
a. Upon one side of the highway, within 0.4 km (0.25 mi), the contiguous property fronting thereon is occupied by 13 or more separate dwelling houses or business structures.
b. Upon both sides of the highway, collectively, within a distance of 0.4 km (0.25 mi) the contiguous property fronting thereon is occupied by 16 or more separate dwelling houses or business structures.
c. The portion of highway is larger than 0.4 km (0.25 mi) but has the ratio of separate dwelling houses or business structures to the length of the highway described in either subparagraph a or b.
2. Pedestrian and bicyclist safety.
-E&TS guidelines from pg. 114 in the MUTCD”

The LADOT has no standards (that I’ve seen) relevant to pedestrian safety except when it comes to removing pedestrian access to speed up cars. What sort of lunatics are running things at that joint?

Maybe we can set up an exchange with the LADOT: they give us streets that don’t kill us and in exchange we let them line up a set number of Angelenos each year and gun them down. That way, we get safe streets and they get the body count they want.

Now the police department says, raise the speed limit and we’ll enforce it. Why didn’t they enforce the 35 MPH speed limit? They’ve had at least seven years to obtain compliance and, according to the Department of Transportation’s so-called Engineering Report, have failed to do. So now the speeders are forcing the speed limit to be increased, and if the past is any predictor of the future, another increase will be in the offing by 2013. Idiotic!