September 23, 2019

Why Are We Building Separated Bike Lanes? Why Not Slow the Streets?


Rod King has a different perspective about  building separated bike lanes and his point is well taken. The head of a British organization advocating for reduced road speed,  King asks why we build great quality separated infrastructure for cycling when the real problem is the speeds that drivers travel at. The higher the vehicular speed, the more problematic any cycling and walking interaction is. He notes that the “The cost of infrastructure is largely the cost of driving at speed and are not costs of cycling and walking.”

In Great Britain “utility cycling” refers to daily biking to work, shops and school. It’s well documented that there are enormous benefits to cycling which includes increasing physical and mental health as well as reducing congestion and increasing air quality. The British Social Attitudes Study found that only five percent of people cycle at least weekly, leading to the question of what is the most impactful way to increase “utility” cycling.

King’s answer? Slow the streets.

The “20 is Plenty” website writes that “Traffic speed and volumes (are) inversely related to walking and cycling levels” and cites the The World Health Organisation’s studies that  20mph (30 km/h)  is the maximum safe speed to reduce catastrophic  conflicts between cars and cyclists. “Safety fears are what people say most puts them off cycling. Cycling casualty rates fall 20-40% with wide area 20mph limits.”

In Britain signing side streets at 20 mph (30 km/h) resulted in a 300 percent increase in cycling to school in Edinburgh. Setting vehicular speed limits of 30 km/h on direct routes can maximize cycling gains.

For traffic engineers the key to fitting in separated cycle infrastructure is finding available land alongside highways or enough carriageway for lanes of a least 1.5m wide (2m is recommended). Yet, what if there isn’t space for a joined up safe separated cycle network? The choice becomes introduce 20mph limits or reduce parking or driving lanes (ie reduce motor vehicle road space). Separated lanes for cyclists and 20mph limits both have their place.”

King argues that  slower streets encourage increased cycling ridership and have little requirements except for signage which he estimates to cost about  1.50 pounds or $2.50 Canadian dollars a person.The more deluxe approach of using  public health expertise for driver education, providing signage and gaining police enforcement of speed limits can cost 2 pounds per capita ($3.30 Canadian) but can provide maximum engagement.

Streetfilms produced this YouTube video below that describes the philosophy of the 20 is Plenty movement and interviews Rod King. There is also a review of neighbourhoods that have reduced speeds for cycling and walking, encouraging physical activity and making the local community socially more cohesive.

Posted in


If you love this region and have a view to its future please subscribe, donate, or become a Patron.

Share on


  1. This is standard AAA practise. Speeds and motor vehicle volumes are the factors. If both are brought low enough then you don’t need protection. If this is not possible (arterial, etc.) then you install protection.

  2. As a cyclist, I’d rather have a bike lane with good physical separation from cars traveling at 50-60km/h than sharing the road with cars traveling at 30-40 km/h. We have both types in the city, and I love the residential portions of the cycling network but please don’t make me share road space on the arterials. And I feel pretty much the same as a driver, too.

  3. Typical American is an SUV or pickup truck with a tall front-end higher than many children’s heads — even young teens. The drivers of these massive vehicles cannot even see what is in front of them. Even at low speeds, a driver can crush a person and not even realize it is happening. Plus American vehicles are permitted to have bull bars placed on their front end, rendering whatever pedestrian-protection devices in the bumper useless.

    Car parking lots and driveways are analogous to UK 20mph streets. Sadly, there are many US pedestrian deaths and injuries in these locations even though speeds are less than 20mph.

  4. Signs alone won’t be enough to ensure motorists actually drive the speed limit, no matter what it is. However, affordable engineering and educational tactics can slow speeds down to a much safer level for all. I agree with Rob that these larger “light truck” models can kill or severely injure at lower speeds, however drivers will have increased visual awareness at lower speeds, since physiological stress (from higher speeds) narrows the cone of focus, which typically is on traffic lanes- the real reason why separate paths, sidewalks and even painted bike lanes are most hazardous at intersections-ie right hooks and left crosses- or vice versa.

  5. “Cycling casualty rates fall 20-40% with wide area 20mph limits.”

    And they fall by 60-70% when protected bike lanes are installed, or more when modern engineering is applied at intersections. These results have been noted in numerous North American cities after concerted efforts were made to separate bikes from cars. Lower limits are great in residential areas, especially if augmented by other traffic-calming devices, but they are no substitute for separate infrastructure.

    Nobody will go grocery-shopping on a bike if it feels like a life-threatening ordeal. Even less will they make the school run by bike if they fear their kids are in danger. To encourage people to cycle rather than drive, you have to make them feel safe, and protected lanes do this much, much more effectively than lower speed limits.

    That is why you build them.

  6. I just returned from a brief trip which saw me in Philadelphia, PA, for a few days. Philadelphia has a dearth of bike lanes, let alone protected ones. My perception was also that the density of traffic has increased phenomenally since I studied there 50 years ago. Congestion was brutal. Lanes were way too narrow. Buses and trucks often occupied 1-1/2 lanes. Everyone, motorists, cyclists, pedestrians, “sped” through downtown at the same speed, ideal and normal for pedestrians, probably a bit slow for cyclists – and requiring a lot of weaving in and out, and likely way too slow for most motorists. However, no one was in danger of more than a nudge from another mode of travel. It works. I understand it’s not ideal, but it is an 18th century city in the 21st century.

Subscribe to Viewpoint Vancouver

Get breaking news and fresh views, direct to your inbox.

Join 7,303 other subscribers

Show your Support

Check our Patreon page for stylish coffee mugs, private city tours, and more – or, make a one-time or recurring donation. Thank you for helping shape this place we love.

Popular Articles

See All

All Articles