An electrical fire on a Bakerloo line train this morning raises a question about the safety and the extent to which the Bakerloo line rolling stock remains fit for purpose.The train on fire arrived into Oxford Circus station right at the peak of the morning rush hour, when some 10,000 commuters use the station in a busy 15 minute period.The Bakerloo line trains are known as ‘72 Tube Stock’ and were introduced onto the line in 1973, so they’ve been operating for 44 years already. The fleet is currently undergoing a deep refurbishment programme, to extend their life through to 2033. The Bakerloo line trains are already the oldest trains running on the UK’s railway network (aside from heritage railways). Is it really appropriate to assume they’ll continue to operate safely and efficiently for another 16 years? We design and deliver infrastructure for a 60 year life, not trains.Passenger numbers are not growing as quickly in recent months, as they have done over the last 10 years, but the work rate for the 36 trains operating on the Bakerloo line isn’t going to get any easier any time soon. Other busier lines, including the Piccadilly, Central and Waterloo & City lines, have been prioritised in the New Tube for London programme, ahead of the Bakerloo line. The incident this morning may require London Underground to reconsider the prioritisation and push the Bakerloo line up the schedule.