The British Rail Class 166 "Network Express Turbo" diesel multiple units (also known as "Thames Turbos" ) were built by ABB at York Works from 1992-93.

These units are the express version of the Class 165 units and belong to the Networker family of trains.

Description

These units are a modification of the Class 165 design. They have a top speed of 90mph (suitable for mainline use), are carpeted throughout and have air-conditioning. Externally, the class 166 can be distinguished from a Class 165 by having a first class section at each end of the train, and opening hoppers on every other window.

Other differences over a 165 are as follows:

• Two toilets (a 165 only has one toilet per unit)
• Tables in first class and in one third of the middle carriage
• Dedicated cycle/luggage storage in the middle carriage
• Different interior panelling between the door and seating areas
• Grab rails painted in yellow instead of the blue found in the 165's

Twenty-one 3-car units were built, numbered 166201-221. Each unit was formed of two outer driving motors, and an intermediate motor. The technical description of the formation is DMCL+MS+DMCL. Individual carriages are numbered as follows:

• 58101-58121 - DMCL
• 58601-58621 - MS
• 58122-58142 - DMCL

The units were built to replace elderly Class 117, Class 119 and Class 121 "Heritage" DMUs, and locomotive-hauled trains on services from London Paddington along the Great Western Main Line.

Six cars were added to the original order in 1991 after Network SouthEast acquired some of the Cotswold Line line services from Regional Railways to allow Class 158 units to be converted to Class 159's for the West of England services.

Operations

When built, these units were operated by the Thames Line and North Downs Line subdivisions of Network SouthEast and therefore carried NSE blue, red and white livery with Turbo Express branding between the two first class windows of the DMCL carriages.

Their main destinations included fast-trains to Reading, Newbury and Oxford, with some services continuing beyond Oxford to Banbury and Stratford-upon-Avon, or along the Cotswold Line to Evesham, Worcester, Great Malvern and Hereford. Units are also used on the Reading to Gatwick Airport services along the North Downs Line. Many services operated by the 166 were branded as Turbo Express in the timetables.

In future it has been proposed to run the Class 166 along with the Class 165 units on the Cardiff Central to Portsmouth Harbour route, subject to line clearance.

Following privatisation, the units passed to the Thames Trains franchise, who introduced a new blue, white and green livery. There were two variants of this livery; the Class 166 units had the 'express' variant.

In April 2004, operation of the Thames Trains franchise passed to the First Group, who now operate the company as First Great Western. The livery remained the same, but FGW Link branding was applied over the obsolete Thames Trains logo.

Fleet details

Class	Operator	No. Built	Year Built	Cars per Set	Unit nos.
Class 166	First Great Western	21	1992-1993	3	166201 - 166221

References