Comments on: Combinations Cause Crashes — Situational Awareness

By: ChipSeal

ChipSeal — Tue, 24 Nov 2009 03:21:36 +0000

RTPAOATPSL: Right To Proceed At Or Above The Posted Speed Limit

By: Keri

Keri — Tue, 24 Nov 2009 02:38:44 +0000

Me too.

And I’ve noticed this:

The percentage of motorists that react badly to a bicyclist claiming the lane is much smaller than the percentage that react badly to a motorist driving the speed limit.

Expectations.

By: Richard

Richard — Tue, 24 Nov 2009 00:08:45 +0000

I’m not so sure the 85th percentile is to blame. Many roads have had the same speed limits for years. I think it is more attributable to a phenomenon called “normalization of deviance.” Basically, the 5 mph cushion given by the law has become normalized over time, so that 10 mph became the cushion. Given enough time, the normalization has continued to the point where someone speeding 15 mph can be tailgated by a cop because the speeder is going slower than the cop wants to go. I was one of those speeders in a prior life, and it happened all the time. Now I drive the speed limit, and it seems I’m the slowest person on the road.

By: MikeOnBike

MikeOnBike — Mon, 23 Nov 2009 21:49:59 +0000

Kevin’s comment: “So if enough morons are going at 200 km/hr [124 mph] that becomes the speed limit?”

Well, it would have to be 15% of drivers going that fast for 200 km/hr to be the 85th percentile. I suspect the police would be on the case for such easy pickings.

By: andrewp

andrewp — Mon, 23 Nov 2009 19:07:36 +0000

In some ways, I was speaking to those of us who have gotten “confident” in our riding skills. In motorcycle riding, the crash percentages go down over time from the first year of riding onwards … except for a bump around year three. Some people believe that time frame is where people get just a bit too confident of their skills and still don’t realize they have plenty to learn and experience …….

By: Kevin Love

Kevin Love — Mon, 23 Nov 2009 17:35:17 +0000

Steve wrote:
“In BC, quite a few highways have 90km/hr speed limits”

Kevin’s comment:
I presume that these are either in rural areas or are limited-access expressways. If we are talking about 90 km/hr down an urban street filled with homes and shops, then I’ve got a problem with that.

By: Kevin Love

Kevin Love — Mon, 23 Nov 2009 17:29:55 +0000

Eric wrote:
“The planners like to use the ’85th percentile’ rule”

Kevin’s comment:
So if enough morons are going at 200 km/hr that becomes the speed limit? Bizarre.

I prefer a policy that urban roads have to be safe (actual safety) and feel safe (subjective safety) for all road users. This requires the setting and strict enforcement of proper speed limits.

By: Keri

Keri — Mon, 23 Nov 2009 16:13:41 +0000

Step Eight: Claim the road is dangerous and browbeat human-powered vehicle drivers for daring to use it.

By: Mighk

Mighk — Mon, 23 Nov 2009 16:06:56 +0000

We have an ugly convergence of factors that have led to so many high-speed roads.

* The aformentioned 85th percentile rule.
* A law that makes driving less than 5 mph over the posted speed un-citable
* Flat terrain, resulting is very straight roads
* Suburban land use setting buildings way back from the street

Step One: build a straight, flat road
Step Two: set the posted speed at the 85th percentile level
Step Three: put buildings far away from street
Step Four: only enforce speed violations of 10 mph or more
Result: average speeds are at least 5 mph higher than posted
Step Five: when widening road, do speed study; find that 85th percentile is now 5 mph higher than original
Step Six: design road for higher speed
Step Seven: do speed study of wider roadway; set new 85th percentile speed which is based on the faster design and faster traffic; add another 5 mph

By: Steve A

Steve A — Mon, 23 Nov 2009 15:30:05 +0000

In BC, quite a few highways have 90km/hr speed limits. There are many cars going significantly faster than that. At least the 85th percentile has a basis other than “I think that’s too fast” by do-good politicians. Removing factors that encourage people to drive faster achieve a better effective speed drop. People drive fast in Florida because they feel safe doing so. THAT is the speed problem there, not the posted limits.

Part of cycling defensively is to anticipate and reduce the probability of multiple simultaneous occurrences. ESPECIALLY those that one has not trained to deal with. In an emergency, the need to THINK can be fatal…