To ask Her Majesty's Government with reference to the Intercity Express Programme's mixed diesel and electric trains, under what combinations of speed and acceleration it is planned that the diesel engine would be used to supplement the power available from the catenary. [HL2376]

Use of the diesel engine on long bi-mode trains depends upon a number of factors. Under the wires, the bi-mode train will move away from each station using only electric power. Above a certain speed, and dependent on gradients, the diesel engine will be used to top up the power available from the catenary either if high acceleration is required by the schedule, or to recover from delay.