The California Department of Transportation (Caltrans) reports that motor
vehicle crashes in California claim 3,600 lives and injure 13,000 annually with 887 of those deaths being attributed to speeding. According to the National Highway Traffic Safety Administration, speeding contributed to 12,151 fatalities nationwide in 2022. Twenty-nine percent of traffic deaths in the country involve speeding.
To curtail the impact of speed on traffic safety, the California legislature passed Senate Bill (SB) 961. Upon Governor Gavin Newsom's signature, new vehicles starting with model year 2023 sold or made in California will be required to have “passive intelligent speed assistance.” Below, we explain the technology behind these passive speed limiters and how speeding contributes to automobile accidents.
What is a Passive Speed Limiter?
A passive speed limiter sends the driver a sound or visual alert when the vehicle reaches a particular speed. California SB 961 would mandate the warning when the car or truck goes ten miles per hour over the posted speed limit. The alerts may come from a “caution” or other light on the dashboard or a computer or artificial voice. Passive speed limiters rely on haptic warnings, such as a vibrating steering wheel. The system determines the applicable speed using global positioning systems (GPS), which may detect speed limits or act in conjunction with a database of speeds for particular areas.
With passive limiters, the driver remains in control. By contrast, an active speed limiter contains measures for the vehicle to not exceed the speed limit. A vehicle with such controls may automatically decelerate to the speed limit through automatic braking. Other active speed limiters may include lowering engine power or providing resistance to the accelerator.
Upon passage, California will become the first state to require passive intelligent speed assistance on vehicles. Already, vehicles in the European Union face the mandate for passive speed limiters. Washington, D.C. requires intelligent speed assistance for repeat offenders of speed limit laws in the District.
How Does Speed Contribute to Crashes?
The higher your speed, the more time it takes to stop. To calculate how long it
takes to stop, you start with the braking distance. At 20 miles per hour, it takes you 40 feet from braking to stopping. The distance at this speed assumes amultiple of two. For every increase of 10 miles per hour, you add 0.5 to the multiple. Consider the braking distances at these speeds:
- At 30 mph (which is five mph over the speed limit in school zones), it takes 75 feet of braking distance to stop (30 x 2.5)
- At 50 mph (which is five mph over the speed limit for most two-lane undivided highways in California), the braking distance is 175 feet (50 x 3.5)
- At 70 mph (which is five mph over the speed limit form most California freeways), the braking distance is 315 feet (70 x 4.5)
- At 80 mph x 5, it takes 400 feet to stop after initially hitting the brakes
Add to the braking distance the “thinking distance.” This represents how long it takes a driver to process an event and to start reacting to it. When you use a
cell phone while driving, you add to the distance needed to stop because you
have not perceived the need to slow down or stop. At 55 mph, a driver who
looks at social media or other content on the phone travels 300 feet – the length of a football field.
Viewing wireless phones and other forms of distracted driving contribute
significantly to rear-end collisions. The National Highway Safety Traffic
Administration attributes 87 percent of rear-end collisions at least in part to
distracted driving. Such collisions account for roughly three out of every ten
automobile crashes.
Overall, according to one study, distracted driving is a factor in four out of everyfive crashes. The California Office of Traffic Safety states that 140 people losttheir lives in California due to distracted driving.
Speed also affects the severity of crashes. The Insurance Institute for Highway Safety tested the impact of automatic braking on the extent of vehicle damage. It had a 2013 Mercedes crash into a 2012 Chevrolet Malibu at 25 mph. That crash caused $28,000 in damage. Using the same vehicles, the 2013 Mercedes, with the automatic braking, crashed into the Malibu at a 13 mph lower speed. The resulting damage was $5,700.
Why Do Drivers Speed?
As we discussed already, distracted driving leads to many crashes. Those looking at smartphones, newspapers, or food while driving do not monitor speedometers or ascertain the need to reduce speed.
Drivers break speed limits and otherwise drive too fast for other reasons.
Lateness appears as a common trigger for speeding. According to a 2021
CarInsurance.com survey of 1,000 motorists, 21 percent of motorists blamed
being late for work. Sixteen percent said they were speeding when stopped
because of being late for a job interview. Running late for court, a doctors
appointment, meeting friends, and either getting or dropping off a child each
accounted for 13 percent of excuses for speeding.
In automobile crash cases, personal injury and insurance defense lawyers seek to discover from the other driver information such as:
- Planned destination
- Time of departure from home or other starting point
- Time and location of the appointment or event to which the driver was headed
- The route which the driver took or was taking at the time of the wreck
- Events or traffic conditions that may have delayed the driver and motivated the driver to make up time
Is Passive Intelligent Speed Assistance Effective?
Unlike active speed limiters, passive systems depend upon careful behavior from drivers to help reduce speed. Consider these actions and omissions that may stunt the effectiveness of passive intelligent speed assistance:
- Distracted driving
- Overriding the system, such as by deactivation or greater force on the accelerator
- Refusing to reduce speed because of lateness, impatience, or wanting to maintain pace with traffic
System malfunctions may prevent warnings altogether or might trigger an alert when the car is not speeding. This might cause the driver to doubt the accuracy of the detection of speeding and dismiss warnings as annoyances.
Whatever the reason, drivers who do not reduce speed in response to audible or visual cues risk causing accidents in congested and other places. According to a AAA Foundation for Traffic Safety report, urban areas saw a 34 percent increase in traffic accidents between 2010 and 2019. Crashes in rural areas decreased by 10 percent during that period. In 2019, urban streets and roads accounted for 54 percent of the 9,748 speed-related traffic deaths.
Active systems – especially those that cannot be overridden -- seem more likely to promote speed reduction. One study notes that mandatory active speed limiters lower fatal crashes roughly by half and serious crashes by 40 percent. Advisory intelligent speed assistance (passive) systems yield a five percent reduction in deadly traffic accidents and four percent less serious crashes.
Although not presently mandatory in the United States, certain fleet owners
have undertaken these measures. For instance, New York City adopted a pilot
program of having active speed limiters on 50 city-owned vehicles.
