The Davis City Council has an item on their consent calendar this evening that is a classic example of the Law of Unintended Consequences. Or as some people say, no good deed goes unpunished.
The basic speed law in California revolves around the 85th percentile. That is the speed that only 15% of the drivers exceed. Vehicle speeds are measured periodically on all major streets. In a town like Davis that would include Russell Boulevard, Covell Boulevard, F Street, Anderson Road, and many more.
Speed limits are supposed to be set at the nearest 5 mile an hour (mph) increment of that 85th percentile speed. However, speed limits can be reduced an additional 5 mph for special circumstances by the Traffic engineer. For example: On a street with a 25 mph speed limit, if the 85th percentile speed is 32 miles an hour, radar enforcement can be used IF the additional 5 mph reduction is approved by the Traffic engineer. If the speed survey shows an 85th percentile speed of 34 mph, the city would be forced to raise the speed limit to 30 mph with the exception, 35 mph without it. With or without that exception, speed limits that are set too far under the 85th percentile speed cannot be enforced with standard radar surveillance.
Two years ago, Public Works Department staff revealed to the Safety and Parking Advisory Commission and the City Council that several dozen street segments in Davis were out of compliance with the 85th percentile requirement. This threatens to compromise the Police Department’s ability to enforce basic speed safety. The map below, attached to the staff report from those hearings, shows these streets.
With that enforcement crisis upon them, Public Works staff recommended and received Council approval for a pilot program that initially targeted 3 streets:
• J Street between 8th Street and Covell Boulevard.
• Anderson Road from Covell Boulevard to Corona Drive.
• Sycamore Lane from Antelope Avenue to the City Limits near the Waldorf School.
In all three cases, speed limits were temporarily raised from 25 mph to 30 mph for a year while repeated speed surveys were taken. It may be surprising to some, but speeds on the streets in question did not change significantly, in spite of the extra 5 mph allowed by the temporary speed limit signs (cost $1,000). The message here is that drivers respond to the signals the street gives them. Wide lanes and open spaces encourage speeds higher than the community may want in quiet residential settings. However, with the new signs that essentially legalize the excessive speeds drivers were going anyway, police may now use radar enforcement.
This gets us to the question of why the speed limits were set at 25 mph on these streets in the first place? The answer is simple: The community and the street engineers felt that was the speed limit most appropriate for these neighborhood settings.
In the J Street case, this is an area swarming with children on foot and on bicycles much of the day heading to and from North Davis Elementary, Cesar Chavez Elementary, St. James School, Holmes Jr. High School, Davis High School, and Da Vinci High School.
This 85th percentile concept was put into law to prevent speed trap towns from nabbing unsuspecting motorists with low speed limits. In our current situation, it now works against basic safety for school children and other residents of strictly residential areas with outdated through streets.
This situation isn’t the fault of anyone in the Public Works or Police Departments. It was created long ago when streets were built in cities using lane widths that were imported from rural highway standards. Those lane widths are safer at high speeds out of town, but encourage dangerous speeding when they appear in towns. Worse, a recent and more rigid interpretation of the 85th percentile rule now jeopardizes the Davis Police Department’s ability to enforce our basic speed laws on many major streets in town.
So what are we to do? Is there an alternative to yielding to the speeding driver behavior that should be examined? Yes, there is.
The fact that driver behavior did not significantly change in spite of the speed limit increase is evidence that drivers are in a large measure responding to the design of the street when they decide how fast to go, not the speed limit signs. So let’s take a look at the design of J Street, for example.
Between 8th Street and Covell Boulevard J Street is 50 feet wide. It is divided up like this:
• 8 feet for parking on both sides.
• 5 foot wide bike lanes on both sides (the bare minimum standard for bike lane width).
• 12 foot wide vehicle lanes in each direction (which exceeds the guideline width in the General Plan).
If drivers respond to lane width, then they are getting a rural highway speed message from J Street. For the minimal cost of buffing off the painted lines between the bike lanes and the vehicle lanes and moving them over, we could have a street that looks like:
• 8 feet for parking on both sides (same as before).
• 7 foot wide bike lanes on both sides (now meeting the Davis and State of California standards for bike lane width).
• 10 foot wide vehicle lanes in each direction (a width many cities are now using).
Some cities are also painting an extra-wide 10 or 12 inch stripe separating the bike and vehicle lanes to further emphasize the narrower space drivers have.
Just this simple trick of narrowing the vehicle lanes by re-striping has successfully reduced vehicle speeds in other communities. There is no reason to think it won’t work here. If, after re-striping, the 85th percentile speed remains above the level where we can restore the 25 mph speed limit, then some simple and inexpensive minor curb extensions and brightly painted crosswalks will complete the job.
Similar proven and inexpensive fixes are possible for the Anderson Road and Sycamore Lane street sections where speed limits have also been raised for the past year.
We are entering a new era for transportation in our cities in America, and elsewhere in the world. For example, Davis’s efforts are now directed towards a target of 25% of all trips being made by bicycle. Yet many studies document that perceived risk is one of the biggest impediments to getting people on their bicycles, or having parents send their children off to school on bikes. Cyclists are intimidated by the speed and intensity of the vehicle traffic alongside them, even if they have bicycle lanes to ride in. We should be working to reduce vehicle speeds, not allow them to creep upwards, and with the same stroke widen bicycle lanes to further increase bicyclists’ comfort levels.
According to Police Department records, in the year preceding the Council decision to embark on this pilot program there were two accidents on the section of J Street in question. Both involved bicyclists. Both occurred on school days at morning school arrival time, around 8 am. Both happened near the busy intersection of J Street and Drexel Drive that is swarming with children at that hour. Do we really want to raise speed limits on this street?
If the community’s standard was 25 mph for years, shouldn’t our goal be to find solutions that get us back towards those speeds, rather than yielding to bad driver behavior encouraged by outdated design?
Good article. I really don’t understand the sense to CA’s system of setting speed limits based on driver speed. I come from the East Coast, where the state of MD sets speed limits based on what is safe, period. And the police enforce those limits rigorously. In consequence, when I visit MD, it is almost like watching traffic in slow motion. Driving in MD is much safer, much calmer, much more relaxing. And I’m talking about the Washington, D.C. area, which is extremely congested.
ERM… for at least the last 35 years, the state of California has had a basic speed law which says you cannot drive faster than what a prudent (and probably sober) driver would, given the conditions… including but not limited to weather, road curvature, visibility, etc. How do we define “prudent”? 85th percentile (85% of drivers, under normal conditions of weather, etc.) which may be reduced by hazards not readily apparent. I challenge you to describe what MD police thinks is safe…. an intoxicated/impaired driver is not safe at 15 mph… on open roads, good shoulders, few intersections, 80 mph may be safe. Local roads, posted at 30 mph, can be VERY hazardous if someone is impaired due to drugs, alcohol, limited visual acuity, early stages of Altzheimers, sleep deprivation, etc., etc, etc.
To hpierce: In the state of MD, the powers that be decide what situations call for what speed limits, period. So for instance, if it is a residential street, it might get a 25 mph speed limit, unless it is in front of a school, in which case it may get a 15 mph speed limit. It has a very defined set of criteria, and enforces it vigorously. As a result, traffic is much slower, calmer, and safer. You almost never see some idiot crossing four lanes of traffic right before exiting an off ramp on a freeway. In MD around the Washington, D.C. beltway, you plan ahead and move over at least a mile in advance. Just about everyone practices defensive safe driving. Visit sometime, and you will see what I mean. It is literally like watching traffic in slow motion as compared to CA.