encyclopedia

THEORETICAL LINE CAPACITY

The maximum number of transit units (vehicles or trains) or spaces that can be carried over a line segment during a given time period with every transit unit operating at the minimum headway that the control system permits. Real operating…

THERMITE WELD

A welding process in which an exothermic reaction produces molten rails to be joined. When the molten steel cools and solidifies, the rails are fused together. Can be performed in the field to join strings of ribbon rail (also called…

THIRD RAIL

On the Red Line, a raised rail parallel to the tracks that serves as the electrical conductor which carries the 750 V.D.C. to the rail car motors through contract with protruding devices, called shoes, that ride on top of the…

THIRD-PARTY CONTRACT

As used in Federal guidelines and grants, any contract or contract modification between the MTA and another person or firm. Use of the term is generally limited to a contract which is to be funded in whole or in part…

THIRD-RAIL SHOE

A metallic sliding contact attached to the trucks of electric rail vehicles for the purpose of collecting current from the third-rail distribution system. (TRB)

THREE C PROCESS (3CS)

A process for planning urban transportation facilities and services that is required by the Federal Aid Highway Act of 1962 and the Urban Mass Transportation Act of 1964, as amended, in urbanized areas. The three Cs standard for a continuing,…

THROUGH ROUTING

The practice of joining the ends of radial transit routes to travel through downtown instead of having each route turn back in the downtown and return to its origin. (TRB)

THROUGHPUT

1. The volume of vehicles passing or people transported past a point or series of points during a given period of time. 2. Traffic. (TRB)