“To begin addressing a chronic design flaw we first need to notice it—like human-scale islands scattered across an auto-scaled network of public spaces meant for the movement of cars.”
— Felix Landry (2019) How Did We Get Used to Out-of-Scale Cities?, Strong Towns.
Available at: https://www.strongtowns.org/journal/2019/5/7/how-did-we-get-used-to-out-of-scale-cities.
Shared Space
The power of an image! The Canberra Transport Photo (2012) We Ride! Australia.
Available at: https://www.weride.org.au/events/the-power-of-an-image-the-canberra-transport-photo/.
Road capacities are hugely affected by how much we share it with others. In any mode of transportation, we claim the space under the vehicle itself, the designed width of the lane that it moves in, and the distance between vehicles (front and back) which increases with speed. If we sit in a bus seat, the sum of our allocated street space is far less than that of an individual car driver.
In the above images, the capacity of one bus is 69 people. With an average of 1.1 people per car, 60 vehicles are required to equal the capacity of one bus. For size comparison, 68 bikes (one tandem) and clusters of 69 pedestrians illustrate the static size needed for each mobility type.
Stopping Space
Stopping distance is a critical measure for highway and road design. AASHTO (American Association of State Highway and Transportation Officials) uses a formula that is only applicable to average cars and trucks, using the following formula:
s = (0.278 × t × v) + v² / (254 × (f + G))
s= Stopping distance in meters;t= Perception-reaction time in seconds;v= Speed of the car in km/h;G= Grade (percent slope) of the road, expressed as a decimal. uphill is positive, and downhill is negative;f= Coefficient of friction between the tires and the road. It is assumed to be 0.7 on a dry road and between 0.3 and 0.4 on a wet road.
The graph to the right and the calculator below help understand the factors determining the distance required to stop a vehicle.
However, one critical aspect that needs to be added here is mass! How do different sizes and weights of vehicles affect the stopping distance? In the formula above, this would change the coefficient of friction, as a bike would have a much different coefficient than a bus. Both modes of transportation are generalized out of these calculations. Engineers would argue that they are traffic minorities on highways. However, that ends up being a self-fulfilling prophecy if the road design makes it dangerous for cyclists (discouraging their use) and if busses continue to get stuck in lanes of car traffic. How would road design parameters change if cyclists and busses were the primary modes determining the calculations rather than personal vehicles?
Stopping Distance for Average Car
Bogna Szyk (no date) Stopping Distance Calculator, Omni Calculator. Available at: https://www.omnicalculator.com/physics/stopping-distance.
Visual Space
Field of Vision
(section still in progress, please stay tuned)
Storage Space
(section still in progress, please stay tuned)