The new trains are back, but their drawbacks remain

This is an extract of evidence given by Roger Ford, a rail expert, to the Welsh Affairs Committee about the cancellation of the South Wales main line electrification:

This brief submission focuses on the current claims by Government that electro-diesel ‘bi-mode’ trains provide an acceptable alternative to full electrification of the line between Cardiff and Swansea .

These claims are not based on a detailed technical and commercial comparison of the alternatives. To be blunt, the claim that bi-mode trains will provide passengers with the same quality of service is a face-saving attempt to justify cancellation of the onward electrification from Cardiff to Swansea. The cancellation is the result of cost escalation and delayed completion of Network Rail’s Great Western Electrification Programme (GWEP).
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2.0 Comparison of electric power versus diesel
2.1 In general, it is important to bear in mind that in both modes the bi-mode represents a sub-optimal solution.

With up to 10 tonnes of diesel power pack and fuel under 60% of its coaches, when running as an electric train a bi-mode is an overweight Electric Multiple Unit (EMU).

In diesel mode it is underpowered when compared with a conventional Diesel Multiple Unit (DMU) DMUs have an engine for each vehicle while at least one bi-mode vehicle will be dedicated to the equipment for electric operation – a transformer and pantograph . Performance is thus degraded in both modes by either excessive weight or lack of power.

2.2 Electric traction equipment is simpler, lighter and offers more power for a given weight compared with diesel equipment. As a result electric trains are lighter. This is reflected in the capital and operating costs.

The average cost per vehicle of recent EMU orders in the UK has been around £1.2 million. The recent contract for 25 Hitachi bi-mode trains for TransePennine Express has an average cost of £2.36 million per vehicle.

This difference is reflected in the leasing costs of the trains.

2.3 Diesel train fleets have a lower availability – the percentage of trains in a fleet in service. This stems from a number of factors including the increased maintenance required by diesel engines and the requirement for time out for refuelling . This means that for a given service level a larger fleet of diesel trains is required, increasing the cost

2.4 Electric train maintenance costs are typically 33% lower than a comparable diesel train

2.5 Energy costs of electric traction are typically 45% lower than diesel. This is the result of a number of factors in addition to the relative costs of electricity and diesel fuel.

Electric trains are lighter and thus require less energy for a given performance. In addition, electric trains can employ regenerative braking which switches the train’s electric motors to generators to slow the train. The electricity generated is returned to the National Grid. Typical energy saving in intercity type operations is 15-20%. A further advantage of electrification is that the railway is able to use whatever source of energy supplies the Grid.

2.6 The lower weight of electric trains results in lower track wear. In the case of the Hitachi Intercity Expres Programme trains, the vehicles in the electric units weigh 41 tonnes. In the bi-mode version, the weight of the diesel engine and fuel increases the vehicle weight to 50 tonnes.

The lower track wear reduces track maintenance costs which are reflected in the Variable Track Access Charges paid by the operator to Network Rail. This benefits fares and subsidy payments

2.7 Because more power can be installed electric trains have a higher performance than diesel trains. This is reflected in the forecast 15 minute journey time saving claimed when the GWR electrified service is introduced, although some of this will be due to changes in stopping patterns.

2.8 With shorter journey times, fewer trains are required to cover the timetable. Note the similar benefit from greater availability already mentioned.

2.9 Electric trains are significantly more reliable than diesel trains. For example, Siemens three most reliable EMUs are currently averaging around 100,000 miles per 3 minute delay. The Company’s equivalent DMUs are recording a creditable, by DMU standards , 26,000 miles per 3 minute delay.

This disparity is also reflected in the specification for the Hitachi trains in the Intercity Express Programme contract. The electric versions are required to achieve 50,000 miles per 3 minute delay, the bi-modes 25,000 miles per 3 minutes delay.