Wednesday, October 19, 2016

Type of Right of Way: separated, exclusive, dedicated and mixed

For the purpose of argument, consider these the basic types of guide-way for urban transportation: Separated, Exclusive, Dedicated and Mixed.

Separated means grade-separation, either elevated or underground. There is also at-grade seperation, which is what freight lines (and most light rail systems) use, railroad gates are used to provide time-separation where roads and railways intersect.

Exclusive means 'transit only', a prohibition enforced with physical separation, typically in the form of either a Jersey barrier or a curb.

Dedicated also means 'transit only', but without the physical separation of a barrier. Typically, this is what is used for bus-lanes. Lacking physical barriers preventing entry and exit, enforcing it is more difficult. It gets used because it is a) cheap, and b) emergency response agencies oppose physical barriers that limit their ability to make U-turns across streets.

Mixed is 'mixed traffic', where the transit vehicle operates like a private vehicle.

There are some other, more exotic variants, but most of those aren't relevant, so I'll cover them in another post.