encyclopedia

NO CLEARANCE

Locations within Heavy Rail where no clearance exists between fixed wayside structures and moving vehicles operating on tracks.

NO-ACTION ALTERNATIVE

(Also known as Do-nothing Alternative, Null Alternative.) A planning option of leaving the situation as it already exists. Existing facilities and services are maintained, and existing transportation policies are continued. See also Transportation System Management Alternative. (TRB)

NO-BUILD SCENARIO

Planning projection of what the future will be like without any new transportation investments added beyond what is currently under construction.

NODE

In planning, a point that represents as intersection of two or more links, highways, or transit lines or a zone centroid; used in trip assignment. (TRB)

NON-BIDDABLE TRIPPER

A driving assignment, more than three hours long but not longer than seven hours, during either the morning or evening peak periods. Some non-biddable trippers, less than five hours long, are assigned to part-time operators. All other non-biddable trippers are…

NON-BRIDGEABLE GAP SECTION

A gap in the contact rail that is longer than the distance between the front and rear collector shoes on a vehicle.

NON-COMBUSTIBLE CONSTRUCTION

Construction minimizing the hazards of fire by the use of non-combustible materials for structural elements or assemblies, and by limiting the amount of combustible materials that are incorporated into the building construction.