encyclopedia

TUNNEL

1. An enclosed passageway, as for trains, automobiles, and so on, through or under an obstruction, such as a city, mountain, river, or harbor. 2. An underground passage. (TRB)

TURBINE ENGINE

A rotary engine actuated by the reaction or impulse or both of a current of fluid or gas subjected to pressure. A turbine is usually made with a series of curved vanes on a central rotating spindle. (TRB)

TURN AROUND LOOP

The bus route segment at the far terminal or short line terminal to reverse direction of the bus for the return trip over the route of the line. Sometimes passengers are allowed to ride or board but on most lines…

TURN BACK

1. In transit operations, to cut short a transit trip (to turn back before reaching the end of the route or line), usually to get back on schedule or to meet peak passenger demands; also known as a short turn.…

TURN-IN TIME

The time at the end of a run that allows the operators to clear their responsibilities (e.g., read farebox, turn in tickets) and prepare their vehicles for storage. The time may be paid or unpaid and may or may not…

TURNOUT

A track structure for diverting rolling stock from one track to another consisting of the switch, a frog and connecting rails. Often “switch” is used to refer to the complete turnout. An element of special trackwork.