WEST COAST TRACTION PERFORMANCE

Alstom Class 390 Pendolinos work most long-distance high-speed WCML services Tilting trains: Fitted with TASS (Tilt Authorisation and Speed Supervision) system, which in conjunction with track ‘balise’ transponders enables curves to be taken at greater speeds with up to 8o of tilt on top of 6o of normal rail cant.

Fleet history : Original fleet of 53 sets

* Conceived for 8-car operation and the first 34 sets initially delivered as such, but strengthened to 9-cars as with the remaining sets delivered from new when it became apparent that the scaled-back infrastructure would not be able to support the originally planned 140 mph running.

* One written off after the Grayrigg derailment in February 2007.

* Fleet now being extended by an additional 106 vehicles. 31 of the 9-car sets to be strengthened to 11-cars.

4 new 11-car sets added to the fleet. The first of the new 11-car sets (390054) is currently undergoing commissioning and acceptance tests on the WCML

Power at the rail of the 9-car Pendolino sets is 5.1 MW (6,836 hp)

* High power : weight ratio of 13.8 hp/tonne * Power distributed over 12 motorised axles

* Designed for service operation at 140 mph (225 km/h) but restricted by the infrastructure to a maximum of 125 mph in enhanced permissible speed ‘tilt’ mode. One of the additional vehicles of the 11-car sets is motorised, only marginally reducing the power : weight ratio to 13.3 hp/tonne

All results in Pendolinos having most impressive performance

In normal operation then often mile after mile of sustained 125 mph running Rarely any significant speed excesses: - generally driven under ‘cruise’ control - TASS over-speed alert/intervention - drivers aware of OTMR and possibility of downloads If tilt not working and the maximum speed is limited to 110 mph then many drivers do their best to make up time, but workings can get out of sequence and lose pathing.

Pendolinos are eco-friendly with regenerative braking - capable of returning full 5.1 MW back into line supply (default to rheostatic mode if o/h line not receptive). Blended with conventional disc friction brakes if high braking rates are required.

Pendolinos now fitted with energy meters - drivers informed of trip energy consumed and regenerated.

Trials with sets operating in ‘power save’ mode with 5/6 of normal traction power - began with 4-day trial with 390049 in Nov 2008 on Mc/r workings. Average 5% energy saving, but large day-to-day variability and was pre-introduction of the enhanced VHF timetable. - since March last year, power saver software installed on 10 sets to assess effectiveness in more intensive service conditions. Typical savings apparently 1-2%, but with reduced acceleration this comes at the price of slightly extended journey times (more later).

Virgin had 16 Class 47 locomotives re-engined as Class 57/3 ‘Thunderbirds’ for the rescue of failed Pendolinos and ‘dragging’ of diverted workings over non-electrified routes during engineering work. High electrical train supply rating, and fitted with hinged Dellner couplers for ease of attachment.

Extensive dragging during the period of WCML reconstruction, but the Class 57s are now little used other than for a weekly Saturday Only ‘knowledge retention’ working along the North Wales coast between Crewe and Holyhead (and return).

* Pendolinos have turned out to be very robust and there are few complete failures of train sets - unlike the WCML infrastructure which more often than is desirable can fall apart, resulting very quickly in major disruption.

* Pendolinos and Super-Voyagers now approved to couple together and to each other for rescue purposes.

* Frequent use of Super-Voyagers and rail replacement coaches to avoid Pendolino drags.

Bombardier Class 221 Super-Voyager DEMUs Used on West Coast Euston - North Wales and Birmingham - Scotland services - until recently 18 5-car sets and 3 4-car sets, but for operational convenience the latter have now been temporarily reformed into 2 standard 5-car sets (with the two spare driving vehicles stored). - with relatively short trains overcrowding can be a problem, and there is frequent criticism of using diesel power for lengthy spells of running on electrified lines.

Again tilt-enabled with TASS control but the maximum degree of tilt of 6o is 2o less than that of Pendolinos ,resulting in some additional lower EPS speed restrictions - with tilt the normal running speed is 125 mph, but again restricted to 110 mph if the tilt system is non-operational - no cruise control facility, but with TASS and OTMR little over-speeding

Each vehicle powered by an underfloor Cummins QSK19 750hp engine with an alternator and convertors/invertors providing 3-phase AC to 2 traction motors - Voyager power : weight ratio at the rail is around 9.2 hp/tonne

Voyagers can (and do) operate with one or more engines out

Again Voyagers normally have spare power in hand, and (without much publicity) all West Coast and Cross Country Voyagers have now had their engines de-rated from 750hp to 700hp - would normally expect around a 40hp reduction in power at the rail, but the actual reduction is apparently much less than this.

There is a proposal from Bombardier to turn Voyagers into bi-mode trains by the addition of an un-motorised pantograph/transformer vehicle (Project Thor) - additional passenger capacity, and a 125 mph train with a still largely acceptable 7.9 hp/tonne. - to many a ‘no-brainer’, but apparently little support from the DfT (possibly because of politics associated with the Agility (Hitachi) IEP/SET bi-mode train project).

OTHER TRACTION REGULARLY OPERATING ON THE WCML INCLUDES: Siemens Class 350 ‘Desiro’ EMUs (LM services south of Crewe and Liverpool) Siemens Class 185 ‘Pennine’ DMUs (TPE services north of Preston) Class 90-powered ‘Pretendolino’ (Mk3 + DVT Pendolino stand-in) Class 90-powered Scotrail Caledonian sleeper services

Interesting to compare the performance of the main traction types on the southbound climb up Madeley Bank after restarting from Crewe

Notes for previous slide

Curves are of acceleration after clearing the 20 mph turnout from platform P5 at Crewe to the Up Fast line. Initial gradients are 1:330 and 269 before the 1:177 after Bentley Road.

Voyagers and Desiros have greater initial speeds as their shorter length formations clear the turnout restriction sooner. Very similar acceleration rates of the two types up to the Desiro 100 mph maximum permitted speed.

The power of the Pendolinos is readily apparent in their acceleration up the bank, with standard sets reaching line speed and needing to be notched back on the steepest gradient. In reduced power mode, the full available power is required for longer to reach line speed just beyond the summit and modelling suggests that any net energy saving on the climb is small (typically just a few percent). With both the reduced power Pendolinos and the Voyagers there is however an additional time penalty approaching ½ minute over the ~6 minute run time of the standard Pendolinos over the same distance.

David Stannard Railway Performance Society April 2011