> High speed, high momentum vehicles are a larger danger to low speed, low momentum vehicles than they are to other high speed vehicles. The danger is only rel

> High speed, high momentum vehicles are a larger danger to low speed, low momentum vehicles than they are to other high speed vehicles. The danger is only relevant if a collision occurs. Motorcyclists also use the roads and they're signicantly lighter than the average passenger vehicle. The average passenger vehicle is signficantly less massive compared to a bus, dump truck, or tractor-trailer. The key to avoiding collisions is to follow the rules of the road in terms of right-of-way rules, signaling in advance one's intention to change course, and positioning when preparing to make a turn at an intersection. > Infrastructure that can be used by high speed vehicles must be designed for high speed vehicles Except that typical surface streets are not designed for high speeds. There are numerous intersections, vehicles waiting to turn, traffic control devices that require one to slow or stop before proceeding, etc. The only infrastructure that meets the criterion you mention are limited access highways where exit and entry are via interchanges as opposed to at grade intersections. > Humans aren't rational - segregated infrastructure is much more appealing to users of the low speed vehicles While it is, it also encourages unsafe behaviors at intersections. Pedestrian rules of movement rely on the assumption that a pedestrian moving at 2 to 4 mph will be close enough to an intersection such that the driver of a vehicle has time to see them and yield to them. Someone on a bicycle moves much faster than a pedestrian. Even casual cyclists go between 6 to 12 mph which is at least twice to four times as fast as a typical walking pedestrian. This means they can be twice to four times as far from an intersection and out of the area a driver of a vehicle normally scans before exiting an intersection when turning. This increases the risk of a collision.