GNER bluesBritain’s East Coast Main Line fleet has again proved vulnerable to heat, some years after a spate of cooling failures on the IC125 high-speed diesel train power cars. With much of Britain basking in unusually high summer temperatures, franchisee Great North Eastern Railway was struggling to keep its electric IC225s on the road. One scorching Friday afternoon in August saw at least three evening peak-hour trains cancelled and another diesel-hauled due to loco failures.Sidetrack’s engineering advisor reports that GNER’s Class 91 locos have been suffering from spurious initiation of the fire extinguishers. Higher than specified temperatures in the equipment compartments fool the fire detectors into thinking that the loco is about to incinerate itself, triggering the extinguishers and emptying the gas bottles. The loco then has to be taken out of service because it cannot run without a working fire extinguisher!Ironically, privatisation may have aggravated this worse-than-usual performance. Changing the IC225’s largely white livery to GNER’s all-over midnight blue has increased the heat build-up due to sunlight. The solar gain is also thought to have increased the air-conditioning load in the MkIV coaches by around 5 kW per vehicle. So that’s why railway carriages traditionally had white roofs!