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Glossary
Browse the A-Z below for some rail-specific terms that are used in this website, together with their meanings.
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T-12

The ability of passengers to obtain travel information, make reservations and book tickets in advance is affected by changes to the timetable caused by Network Rail taking possession of lines in order to maintain, renew and enhance the network. Under Condition 9 of its network licence, Network Rail is required to ensure that accurate timetable information is available to train operators at least twelve weeks in advance.  At the beginning of 2004 Network Rail was in breach of this requirement, with many operators unable to take firm bookings, adversely affecting service to customers.

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TfL

Transport for London
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TOC on TOC

Where a delayed train service of one train operator delays those of another train operator.

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TOCs

Train operating companies: run the (passenger and freight) trains and services on the network. The representative body for the passenger operating companies is the Association of Train Operating Companies (ATOC).
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TOPS

Total Operations Processing System.

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TPWS

Train Protection and Warning System.
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Track

Section 83(1) of the Railways Act 1993 defines “track” as follows:
“any land or other property comprising the permanent way of any railway, taken together with the ballast, sleepers and metals laid thereon, whether or not the land or other property is also used for other purposes; and any reference to track includes a reference to:
(a) any level crossings, bridges, viaducts, tunnels, culverts, retaining walls, or other structures used or to be used for the support of, or otherwise in connection with, track; and
(b) any walls, fences or other structures bounding the railway or bounding any adjacent or adjoining property”.
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Track circuit

Track circuits are designed to detect the presence of a train, by use of an electrical circuit which is completed by train wheels and axles.

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Track circuit failure

Failure of a track circuit or associated equipment, including axle-counter failures.

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Track geometry

The level and alignment of the track.

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Train

Section 83(1) of the Railways Act 1993 defines “train” as follows:
“(a) two or more items of rolling stock coupled together, at least one of which is a locomotive; or
(b) a locomotive not coupled to any other rolling stock”.
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TRUST

Train Running System TOPS.  A train running and punctuality monitoring system, mainly fed by automatic inputs from signalling systems.

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TSR

Temporary Speed Restriction imposed for safety reasons. This can arise from the poor condition of track, structures, earthworks, hot weather effects, or following track relaying until the track bed is stabilised.

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TSR (COT)

A type of Temporary Speed Restriction that has been imposed specifically due to the poor Condition of Track (COT).

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