Legal Obstacles To Safe Streets: California Speed Limit Laws

Ghost bike - by Andrew Said
Ghost bike – by Andrew Said

Every day we hear about drivers killed in collisions on their way to work or pedestrians mowed down when crossing the street. You may be asking yourself, “Why doesn’t anyone do anything about this? Aren’t there laws to prevent this?” Believe it or not, there are legal obstacles to making our streets safer. We have laws dating back to a more car-centric era. These laws treat pedestrians and cyclists as afterthoughts. If we want active transportation to be accepted by mainstream America, a legal framework will have to evolve to protect all of our road users.

In this series, I will examine legal danger zones and potential fixes for reducing traffic-related deaths in California.


One of the most obvious places to start is speed limits. Since we know conclusively that speed kills, why don’t we set lower speed limits?

A 10 mph reduction in vehicle speed from 40 mph to 30 mph, means that a pedestrian who is hit by a car has just increased his or her chance of survival from 10 to 50 percent.

In Los Angeles, police are unable to ticket speeding drivers for violating the posted speed limit on 75 percent of the city’s streets. Why not? It is because the speed surveys required by law for these streets have expired. There is a fear in the active transportation community that the city would be legally required to increase speed limits, further endangering the public, if these speed surveys are conducted.

How did we arrive at such an absurd state of affairs?

California law requires that speed limits be set based on the “prevailing speed.” The prevailing speed is determined by a speed survey which calculates the speed of cars in the 85th percentile. Once this speed of majority drivers is determined, the law only allows an additional 5 mph reduction to account for unforeseen safety conditions. This method of determining the speed limit does not consider the severity of injuries inflicted on a pedestrian or cyclist if hit by a car travelling at the prevailing speed. This needn’t be the case. Alternative speed-setting methods have been effectively used both stateside and overseas.

In countries with the highest rates of bicycle ridership, the severity of injuries caused by crashes at a given speed is taken into account when establishing speed limits. This approach is known as Injury Minimization, or Safe Systems. The idea is to minimize the probability of death and serious injury. It is derived from Sweden’s Vision Zero initiative which dictates that car crashes will occur no matter what; therefore, our road systems ought to be designed to protect us. If we wish to have a larger percentage of people engaging in active transportation, this approach deserves a look.

While the Safe Systems approach started in traditional bike meccas such as the Netherlands and Sweden, the philosophy is gaining traction in other jurisdictions as well. Throughout the United Kingdom, the 20’s Plenty for Us campaign has succeeded in reducing speed limits to 20 mph in more than half of the largest urban areas in Britain. This movement encourages people who walk or bike to use the road system safely. Places adopting the lower speed limits results in more children walking and biking to school. 

New York City is the first major urban area in the United States to usher in lower speed limits to reduce death and injury. Thanks to strong advocacy from Transportation Alternatives, Mayor Bill de Blasio signed the 25mph speed limit into law in 2014. Additionally, Oregon and Washington have both passed legislation allowing for 20 mph speed limits.

There is a glimmer of hope for us here in California. There is already an existing exception to the dreaded prevailing speed/85th percentile law: the school zone. This is a legislative exception carved out to protect vulnerable people, namely children. School zones are exempt from the typical speed survey calculations and mandate a 25 mph speed limit when children are present.

What about designating a pedestrian zone? Or an active transportation zone? The same rationale of protecting vulnerable road users could apply. Don’t children who walk to school deserve the same protections as children who are within the school zone?

If Californians want to experience the benefits of lower speed limits, our work is cut out for us. First, we need a fair and enforceable standard for setting speed limits; second, we need a legislator to champion the cause. The Swedish/Dutch Injury Minimization approach is a solid place to start. We can also learn from successful campaigns implemented in the UK and states such as Oregon and Washington.

The challenge of eliminating traffic deaths is great, but the risks of inaction are unconscionable.

Andrew Said is a prosecutor with the Office of the Los Angeles City Attorney. He focuses on safe streets and active transportation. When he’s not at work, he loves to be outdoors.

  • Derek Hofmann

    Or we could redesign our streets to be inherently safe instead of depending on signs to make them safe. Let’s start by putting back in the roadside trees that were removed because cars kept crashing into them.

  • DukeGanote

    Certainly agree with your first statement; repainting the numbers on poles (speed signs) without serious road redesign is either fantasy or an excuse for turning the traffic stream into a revenue stream.

  • Yes, we should redesign our streets, but in the meanwhile, let’s save lives by reducing speed limits. It will save only some because many drivers will go over the speed limit, just as they do today, but every single life is worth it. The change will support the social change that is only beginning, to see going over the speed limit as similar to driving drunk, a sociopathic behavior that should not and cannot be tolerated in a progressive society.

  • Derek Hofmann

    To make speed limits stick, we either have to change that 85th percentile law, or dramatically increase police visibility in order to scare people into compliance. Or does anyone make inflatable police cruisers?

    On the other hand, it would be cheap to temporarily redesign problematic streets with traffic cones and K-rails.

  • I agree that temporary re-design is valuable, particularly if focused on high crash corridors and intersections. But I still want lower speed limits.

  • Andrew Said

    Speed limits are just part of the toolkit that can be used to make streets safer. I was writing specifically about legal fixes to dangerous streets. Designing safer streets is necessary, however that’s more of an engineering fix. As far as enforcement, that’s easy too. All we need is speed cameras. They are very common in other countries and very effective.

  • M

    There are streets being repaired, repaved, repainted, sidewalks being laid, signals being adjusted, etc. EVERY day in a city like LA. Designs that take pedestrian and cyclist safety seriously should be integrated immediately into those regular repairs so we at least STOP doing what we’re doing since we know it isn’t working.

  • User_1

    Redesign how a speed is determined on a street would be a GREAT step. Having the 85th percentile determining that is so absurd and archaic. All this does is make the limit higher for speeders to cross and become more dangerous to us all. Change the way speed is determined and ENFORCE the present limits.

    Nowadays speeders can go 10mph over the posted speed and they would never face a speeding ticket. Start giving tickets for going 5mph and faster over the posted speed would save countless lives and doesn’t need billions of traffic redesign or what have you. All that needs to be done is enforce the current laws and the infrastructure that’s out there.

  • Ken

    Agreed, and add automated enforcement (i.e. speed cameras)

  • User_2

    You’re article makes many claims but does very little to support them with real evidence. You state that “we know conclusively that speed kills” but the source you provide does not supply any from of evidence to support their claims. No research was done or at least provided, to substantiate their claims that a lower speed limit lowers fatalities. There very well could be any number of factors that cause traffic related death including distracted driving, a drivers inability to follow or lack of knowledge about traffic law, and a drivers ability to perform. Their conclusion simply does not use sufficient data, their argument is fallacious.

  • Joe

    It seems like you must’ve noticed in passing about how to support arguments based in evidence in other comment sections, but lack common sense. Speed kills in the same way that a bullet kill. A very fast object hitting a person will kill them. If a bullet is just thrown at someone, it is very unlikely to kill someone. However shot from a gun it will. The car is the same way. If you would like some data please refer to any of the publicly available trauma databases as well as trauma criteria from the American College of surgeons which specifies what speed constitutes a much higher risk of injury or death. This will get you started in your research.


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