Recently, there have been some critics speaking out against Class IV bike lanes, claiming that they are not safe for cyclists, they cause more accidents than roads without them, they cause a slower emergency response, and are part of an “anti-vehicle agenda” as Republican Mayor and County Supervisor candidate John Franklin in Vista, CA puts it. Surprisingly, these critics have even included one cycling group. I decided to take a deep dive to look at their concerns and see whether the evidence shows their claims are valid. Below are the claims, and the evidence about whether they are true or not.
Common Claims
Class IV lanes increase safety for everyone.
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Claim: Class IV lanes don’t improve safety for cyclists compared to other lanes
Fact check: FALSE
The safety record of Class IV lanes is backed by years of data. The data shows that they are much safer than every other kind of bike infrastructure except Class I trails. This is because the great danger to cyclists is not from other cyclists or pedestrians, but from vehicles. The Federal Highway Administration’s Crash Modification Factors for Separated Bicycle Lanes, states, “Converting an existing constrained bike lane to a protected bike lane can be expected to reduce motor vehicle-bike crashes by over 50%.”
Other studies show significant improvements for protected bike lanes compared to other lanes. One study, a 13 year longitudinal study of 12 large US cities, shows that, per the University of Colorado Denver news, “safer cities aren’t due to the increase in cyclists, but the infrastructure built for them – specifically, separated and protected bike lanes… [which are] significantly associated with fewer fatalities and better road-safety outcomes.” A 2012 National Association of City Transportation Officials (NACTO) study showed that Class IV lanes had the lowest risk of all types of biking infrastructure. Another study from 2010 by the Harvard School of Public Health showed that Class IV lanes…”had a 28% lower injury rate.” A study from Ryerson University in Canada in 2012 states, “features that separate cyclists from motor vehicles…were associated with significantly lower injury risk to cyclists.” There are many more state and local studies as well which prove the safety benefits of physically protected lanes.
There have been studies which show there is not any improvement, but those have been found to be flawed. One that is often referred to by those against protected lanes is a 2019 Master degree paper from the University of Nebraska looking at lanes in Denver, CO. It posits that bicycle crashes significantly increase with the use of any bike infrastructure on roads, including Class II and Class IV lanes. However, the methodology used overcounts crashes by quadruple counting intersection accidents to every single road segment that touches that intersection (regardless of where it occured), and does not account for bike volumes, vehicle volumes, or vehicle speeds on the chosen segments, among other issues.
Claim: Class IV lanes slow emergency response
Fact check: FALSE
This has been a fear expressed by some Cupertino Councilmembers, though studies on Class IV lanes show that emergency response times are not any slower. Some examples are this study from the University of Iowa in 2024, and this study in 2024 from Transportation Research Interdisciplinary Perspectives, which determined that even eliminating a complete lane in a “road diet” did not affect emergency response.
What actually does increase emergency response? The volume of high-injury accidents in a municipality and the loss of personnel due to injury by motor vehicles. Both of these are significantly decreased by Class IV lanes and by lower vehicle speeds which also allow emergency personnel to stand safely away from traffic.
Some critics contend that Class IV lanes do not allow cars to pull over, but no Class IV barrier is continuous–so vehicles can. They allow for large-truck turning movements at intersections, and often have large gaps in the barriers that emergency vehicles can drive through. Newer barrier designs allow emergency vehicles to surmount them.
There are many easily driveable gaps in the McClellan lanes.
“Road warrior” spandex cyclist (top) may wish to ride at high speeds and in big groups whereas everyday riders to school, errands, etc. (bottom) have different needs
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Claim: Cyclists themselves don’t like the lanes
Fact Check: FALSE (for recreational cyclists), TRUE (for some ‘spandex’ cyclists)
Recreational cyclists enthusiastically embrace protected bike lanes, even in places with heavy traffic. Many people say they feel safer and more comfortable by reducing the risk of accidents. In a study of 28 US cities published just this year by the University of New Mexico, it was found that protected bike lanes almost double the ridership compared to standard lanes–and increase the number of cyclists more than 4x over no bike lanes. The Federal Highway Administration agrees: “Studies and experience in U.S. cities show that bicycle lanes increase ridership.”
Riders of high-speed road bikes tend to not be as enthusiastic about Class IV lanes and I’ve heard this even in Cupertino. These riders get frustrated riding in the lanes behind slower cyclists, feel “hemmed in” when riding at higher speeds (18mph +) in the lanes, and dislike the inability to ride side-by-side in a peloton on these roads. Some of these cyclists are less concerned about traffic dangers than more casual riders, subscribing to the Vehicular Cycling philosophy which encourages a ‘school of hard knocks’ for anyone wishing to bike on the street. They have encouraged building only sharrows and Class II (paint stripe) lanes which maximize bicycle speed while providing little safety for cyclists. It isn’t necessary to choose one or the other, though: high speed cyclists are not required to use a Class IV lane. Riders are almost always allowed to cycle in the drive lane even when a bike lane is present.
Class IV lanes make biking accessible to all, whether kids on the way to school, less confident riders, seniors with tricycles, for residents to get to local destinations or run errands, and for families with small children to enjoy a leisurely ride to the local park. It’s infrastructure that is designed for riders of all abilities, not just those that are comfortable mixing with cars or on the side of a painted stripe next to traffic. This is likely why ridership increases are seen in every municipality that installs them.
Claim: Adding Class IV lanes will slow traffic and cause traffic jams
Fact Check: FALSE
Research shows that Class IV lanes do not affect traffic, and may even help reduce overall congestion by (1) encouraging more people to bike rather than drive, and (2) preventing accidents and eliminating conflict points which cause slowdowns and delays, and (3) improving safety and traffic flow with lane width reductions. Furthermore, these bike lanes typically cause drivers to slow down because the street is more ‘active’ with cyclists and pedestrians, which increases safety for everyone–including motorists.
Protected bike lanes increase ridership, reducing the demand on a street. Many studies show Class IV bike lanes increase ridership and encourage new types of people to consider cycling who would not have otherwise. According to a study this year on bike lane types in Baltimore, MD, the most effective way to encourage non-users to ride more would be to construct additional separated bike lanes. The Institute for Operations Research and Management Sciences (INFORMS) published a paper in 2024 which shows that adding a network of protected lanes can double ridership.
Opponents complain that adding Class IV bike lanes will always result in the loss of car travel lanes, but this isn’t always the case. Many successful bike lane projects preserve existing lanes, merely narrowing them to make room for the bike lanes. One example is McClellan Road here in Cupertino, which started as a two-lane road, and is still a two-lane road but now with Class IV lanes along most of its length. And, in case anyone is concerned that narrower lanes cause more accidents, a Johns Hopkins study from 2023 of over 1100 streets in seven cities shows that’s not the case. The number of crashes on a street with standard 12-foot lanes is significantly higher than on streets with narrower 9 foot lanes at the typical city 30-35mph speed limits. “On streets that are busier, have trees, lots of pedestrians, a bike lane, and bikes on the street, drivers feel less safe driving fast and will drive slower, regardless of the speed limit.” A slower speed of cars also substantially reduces the risk of crashes, per the same study.
Traffic congestion is a complex issue influenced by various factors like road/traffic signal design, traffic volume, and driver behavior. It’s clear, though, that installing Class IV lanes will not cause increased congestion, and regular paint stripe bike lanes, even buffered, will not either.
Claim: "Right hook" accidents and intersection accidents are more common with Class IV lanes
Fact Check: FALSE
There’s no studies that show right-hook accidents are more prevalent with Class IV lanes. Right-hook accidents, whereby a car turns right in front of the bicyclist’s direction of travel, are indeed terrible, and occur everyday. However, there does not appear to be any study evidence that they are more common with Class IV lanes compared to paint stripe lanes or sharrows, nor that Class IV lanes “reduce the caution” that drivers take.
In NACTO’s multi-city safety study of more than 170K cyclists and 540K vehicles, Advancing North American Design Practices to Mitigate Bicycle Right-Hook Conflicts, they showed that intersection signaling with protected right turns for bikes results in a 93% reduction in conflicts. This is the very type of signals that have been and are being installed as part of the Stevens Creek Boulevard Class IV lanes.
There is also no evidence that Class IV lanes increase injuries at intersections, such as this study from the University of British Columbia. What’s clear is that how the Class IV lanes are implemented at the intersections matter. To continue the safety benefits well-documented for Class IV lanes on roadway segments, specific design consideration should be given to: providing dedicated spaces for motorists to wait while yielding to bicyclists and pedestrians, separating bicycle crossings from pedestrian crossing, and providing space for turning and queuing bicyclists (CalTrans Memo, 2022).
Typical road design with paint-only bike lanes or no bike lanes (sharrows) provide many conflict points while a vehicle is turning. . This makes it safer for all road users including cyclists, motorists, and pedestrians. Further, a study in Accident Analysis and Prevention in 2021 showed “protected intersections result in a higher rate of right glances [by drivers] at the intersection prior to a right turn,” showing that vehicles are more aware of cyclists traveling in Class IV lanes at protected intersections.
Good intersection design is important, such as proper signaling and keeping the barriers as close to the intersection as possible.
Other Claims
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Claim: Class IV lanes are not safe for cyclists, as cyclists can hit the barriers.
Fact check: FALSE
Certainly cyclists can hit the fixed barriers, though it makes much more sense that a cyclist would run into an object that is not in the bike lane every day, or not easily seen in their peripheral vision. I find that hazards such as potholes/uneven surfaces, tree branches, and trash cans pose the biggest issue, though they don’t generally cause severe injuries or worse. Locally, Cupertino’s Vision Zero dashboard shows no severe injury incidents since 2018 on its protected lanes on McClellan and Stevens Creek Boulevard.
This is not to say that physically protected lanes can’t be poorly designed or placed, leading to avoidable accidents. The lanes could be more prone to accidents for cyclists if the bike lanes are (1) built with a narrower than recommended width (especially if the width varies), (2) do not have high-visibility paint, bollards, and/or reflectors on the barrier area, or (3) the road architecture does not suit them, such as on steep hills.
Claim: Class IV lanes are experimental, and there have been no studies on their use.
Fact check: FALSE
Class IV lanes have a long and documented history, and are recommended in numerous manuals both state and Federal. The 2018 Cal Trans (California Transportation) Manual on them says…”Class IV Bikeways provide an alternative to other bikeways…in a manner that improves safety for all users.” The Federal Highway Administration’s Planning and Design Guide (2015) states, “Vertical elements…provide the comfort and safety that make separated bike lanes attractive facilities.” There have been numerous studies on their use, including from the State Smart Transportation Initiative in 2014, and even comparing them to other or no bicycle facilities, such as a 2012 research paper published in the American Journal of Public Health. That study found that Class IV protected lanes have “about one ninth the risk” of no bike lanes, and 1/5 – 1/6 the risk of standard painted bike lanes, depending on if the street has car parking.
Claim: Class IV lanes “coddle” children, not allowing them to learn how to ride with traffic in the real world
Fact check: FALSE
Bike skills take time to learn. It is shocking that some are comfortable with a potential tragedy of a child being killed or seriously injured because it was decided they should learn through the ‘school of hard knocks’. Many studies and the guidance from CalTrans show that Class IV bike lanes keep everyone safe, whether young or old.
Cupertino Safe Routes to School has bike skills programs which teach students road safety through Middle School Bike Skills Workshops, and even in-school classes. Having them learn biking which deliberately increase the potential for life-altering injuries is cruel and nonsensical.
Claim: Some municipalities are pausing/stopping building Class IV lanes due to “safety”
Fact check: FALSE (with the caveat that poor implementation can cause issues)
It is true that some municipalities are stopping or removing Class IV lanes, but this appears to be due to politics and poor implementation of protected lanes, not any inherent issue with the lanes in general.
A local news station, NBC 7 in San Diego, had a recent news story about how the city of Vista, CA is removing the Class IV barriers which they installed just two months prior. The mayor of that city, John Franklin, called them an “obstacle course” and contends bike lane safety features like these are part of what he calls “an anti-vehicle agenda”–a purely political stance not based upon safety. Upon further research, I found the newly installed barriers were black and had not been painted yet with reflective paint or had bollards on the top yet to mark them. They were being hit by cars in areas with no streetlights and on higher speed, hilly roads. After just two months, with uncompleted visibility work and no effectiveness study, this clearly isn’t a decision that was made based upon safety.
In Encinitas no changes are planned but experienced ‘spandex’ cyclists have made their case in the Encinitas Transportation Commission against the Class IV lanes which were installed in 2019 along Highway 101. The barrier lanes have shown significantly increased ridership, but they are not popular with racing bike enthusiasts, who prefer Class II lanes or sharrows, per public comment. They point to accidents in 2020 in the newly built lanes, and feel unable to ride at high speeds in the Class IV lanes. The bikeway implementation is also poor, as there are no sidewalks for long stretches (causing pedestrians to use the lane as a walking path), and there are poor transitions near local businesses. Improving the implementation, adding sidewalks, and having high-speed cyclists support the safety needs of other cyclists would move these lanes from a partial to a complete success.
Claim: Class IV barriers can’t stop cars anyway
Fact Check: FALSE
Slowing or stopping a vehicle reduces injury severity, which Class IV lanes can do. Whether a vehicle is stopped or just slowed significantly by a Class IV concrete barrier can vary greatly by the expected speed, size and bumper height of the vehicle and the size and shape of the barrier. It’s impossible to state whether a barrier would stop a car in general without considering these factors. I searched for videos of cars hitting standard curbs from the side (as would be expected for Class IV lanes). One shows a high speed car which doesn’t go over the curb, another with a high-speed truck which doesn’t go over the curb either.
Many drivers report feeling a roadway is “narrower” with the lane barriers, even if the car travel lane is the same width as before installation of the bike lane protection. This causes drivers to slow down, which can also decrease the severity of any accident, for a cyclist or a driver. (Accident severity is simply a matter of physics. The faster the vehicle is traveling and the heavier it is, the more severe the accident.) Regardless, even if a barrier does not stop every vehicle–a Hummer at high speed may be impossible, for instance–it will slow or stop enough of them to prevent tragedies.
Claim: Class IV are not as safe as Class I off-street paths, so we shouldn’t build them
Fact Check: FALSE
The problem with this argument is summarized by the phrase “making perfect the enemy of good.” Though Class I lanes are the ‘gold standard’ for safe biking infrastructure, they are just not possible in most locations. Class IV lanes are a good safety runner-up.
Class I paths sometimes aren’t installed due to their high cost, but more often it’s because there just isn’t the right-of-way or easements available to make them happen in cities that are attempting to add bike infrastructure that have not been designed for it previously. Class IV lanes are second best to Class I, but are still significantly safer than the other options, such as Class III sharrows (banned now by CalTrans on any road over 25mph) or Class II paint-stripe lanes which have a high propensity of “dooring”, right-hook, or just plain distracted driver accidents whereby a car drifts into a bike lane. Vision Zero plan recommendations for roads with high KSI’s–including in Cupertino–are almost invariably Class IV lanes because all the available data backs the conclusion that these are the safest options that are actually buildable in most locations.
One last note is that not everyone is in favor of Class I shared walk/bike paths. On paths with a high number of cyclists and on hilly paths (where cyclists tend to go faster), pedestrians can be worried about accidents and conflicts with cyclists. Class IV lanes keep cyclists in their own lane, leaving pedestrians to use the sidewalk alone and vehicles to the drive lane.
Conclusion
Based on the extensive number of studies of Class IV and other bike lanes, these claims about Class IV physically separated bike lanes have been debunked.
Class IV lanes are clearly much safer than Class 2 (paint stripes) and especially safer than Class 3 (sharrows). Class I trails are most desired, but of course they can be impossible to build in many locations. There’s no sign that protected lanes increase right-hook accidents, that the barriers don’t stop cars going into the lanes, or that the decision to stop building the lanes in some cities is due to safety. Some high-speed ‘spandex’ riders and drivers don’t like them, but it’s clear they increase cycling wherever they are installed, sometimes dramatically. They don’t slow emergency response time.
Like any infrastructure, they need to be installed thoughtfully and with careful attention to detail. Poor markings and visibility, stopping the barriers too soon before intersections, or not pairing the lanes with adequate pedestrian infrastructure are just three of several issues that can cause conflicts and accidents. Studies show that they do not increase congestion, and reducing lane widths to install them can increase safety for all road users.
Along with many others, I have seen the increase in students on McClellan using those protected lanes to get to school. We can get a city that meets its vision of zero fatalities and zero serious injuries–and Class IV protected bike lanes are a great tool for us to meet that goal.