Why “Protected” Bicycle Lanes Violate the Principle of the Space Cushion
The concept of a space cushion revolves around maintaining adequate space around a vehicle to provide a spatial and temporal buffer for unexpected events, such as sudden stops, swerves, or obstacles. This principle is critical for ensuring that a person has enough time and room to perceive hazards, make decisions, and take corrective actions. It’s a foundation for the basic speed rule concept and defensive driving.
For drivers of motor vehicles, the automobile itself provides physical protection, and the general-use travel lanes, which are wider than the vehicle’s width, provide a space cushion. Motorcyclists lack such physical protection but safe and defensive motorcyclists rely on riding in the center of the traffic lane to maintain a space cushion. Similarly, bicyclists who use the full width of a traffic lane enjoy the same benefits of a space cushion. However, bicyclists who engage in “edge” or “pedestrian” behavior often operate with a far smaller space cushion.
Bicyclists, often perceived as slow-moving, are frequently given little to no space cushion in cycling infrastructure, particularly in “protected” bicycle lanes and other engineering atrocities such as door-zone bike lanes. This leaves users of such “infrastructure” with inadequate time and space to perceive hazards, make decisions, and take corrective actions. The concept of a space cushion as it pertains to cycling is discussed by Wayne Pein who writes his own blog called Bicycling Matters.
Pein’s article on the space cushion is a masterpiece that remains largely unknown and misunderstood among cycling advocates and so-called engineers who stamp and approve bike lane projects. This lack of awareness has severe consequences for the ideological drive to promote “protected” bicycle lanes and for bicyclists who naïvely rely on such “protection” for their safety.
The entire article on the space cushion is available below in PDF form. Pein’s original article doesn’t mention this type of “infrastructure,” but this article will expand on the space cushion concept as it relates to “protected” bicycle lanes.
The Fallacy of “Protected” Bicycle Lanes
“Protected” bicycle lanes are often promoted as safe spaces for cyclists “of all ages and abilities,” separating them from motor vehicles with barriers such as bollards, curbs, or parked cars. While these lanes aim to shield cyclists from direct interaction with motor traffic mid-block, they fail to address driveway and intersection crashes—the most common and often fatal collisions with cars along with bike-bike crashes and solo bike crashes with the items meant to “protect.” Their confined design inadvertently violates the principle of maintaining a space cushion, essential for safe cycling. These lanes reduce reaction time, making it difficult for cyclists to properly see and interpret potential dangers such as other lane users, turning and crossing vehicles, debris, or the protection elements themselves. They also provide insufficient space for cyclists to maneuver or brake effectively, even at slow speeds. Additionally, they offer little to no room for error forgiveness or recovery.
Inadequate Width and Obstructive “Protection”
Many “protected” bike lanes are designed with minimal width often in accordance with “standards”, limiting cyclists’ ability to maneuver around obstacles. If a cyclist encounters a hazard, such as a parked car’s open door, debris, a bollard or another person, they often have no choice but to stop abruptly or risk a collision—provided they even see the hazard in time.
The skills required for defensive bicycle riding must be acquired through education and experience, which undermines the claim that these lanes cater to “all ages and abilities.” Defensive bicycle riding skills are no panecea however and even experienced cyclists still encounter issues using “protected” bicycle lanes.
“Protected” bike lanes also fail to provide adequate space cushions due to fixed obstacles such as wheel stops, bollards, or curbs used to separate bike lanes from motor traffic. These elements reduce the effective space cushion and force cyclists into tightly constrained routes, increasing the likelihood of crashes caused by inattentional blindness or misjudged maneuvers.
Lack of Escape Routes
Defensive driving courses emphasize the importance of escape routes with perhaps one of the most famous being the Smith System Driving rule of “Leave Yourself an Out.”
“Protected” bike lanes reduce or sometimes eliminate this critical safety feature. For example, if a pedestrian steps into the bike lane without warning, a cyclist may have no room to swerve safely due to barriers on either side. In some cases, the “protection” itself becomes a source of danger. Such “protection” fails to even stop a speeding car from entering the bike lane. Solo cyclist collisions with “protection” elements are common wherever such infrastructure is installed, and legitimate Principle-Driven cycling advocates cite this as a reason to avoid building “protected” bicycle lanes.
Psychological and Physical Hazards
The lack of a space cushion in confined bike lanes can lead to heightened psychological stress for cyclists. Feeling boxed in impairs decision-making, leading to distraction and an increased likelihood of errors. Sudden terminations of “protected” bike lanes at driveways and intersections exacerbate these risks, as turning and crossing motorists often appear suddenly and without warning.
This phenomena can work in the opposite direction too with cyclists persuaded by the “protection” dogma and the relative lack of motor vehicles thinking they’re protected from dangerous hazards thus defocusing them from looking for other hazards.
Some Proposed Solutions
To mitigate these issues, any bicycle lane design should one need to be built must prioritize maximizing the space cushion. Lanes should be of sufficient width, with U.S. engineering standards recommending a minimum “design cyclist” width of 40 inches, which includes a small space cushion to each side of a typical standard bicycle’s handlebars. However, most lanes require greater width, and if “protection” elements are used, ample space—highlighted by edge striping—must be included as a buffer or “gore zone.” Escape routes should also be factored into designs. It might be better to just build an “unprotected” bicycle lane with a sufficient painted buffer and enforce the laws against parking or stopping in bicycle lanes if a jurisdiction has them.
Unfortunately for “protected” bike lane advocates, these measures often conflict with spatial, budgetary, and political constraints.
In Closing
The tradeoffs associated with “protection” in most contexts and designs are often not worth the risks. Proper design principles prioritizing space cushions must be implemented to ensure safe and effective cycling infrastructure.
The next article will examine the phenomenon of solo cyclist collisions with “protection” elements, highlighting cases such as those that plague the Cardiff Bikeway where legitimate cyclists have been keeping track of the various issues while segregationist bike lane activists and incompetent bureaucrats downplay and ignore them. It will further explain why solutions such as “just slow down” or “pay more attention” are insufficient remedies for these systemic issues.
Thanks for the great article! I’ve applied for and hope to be appointed to the Mobility and Safety Commission in my home town and plan to use these articles if/when the need arises as others make efforts to install more “protected” bike lanes.