Neil Turner's Blog

Blogging about technology and randomness since 2002

Tragedy in Croydon

Photo of Croydon tram
Photo Copyright EPA

Wednesday was a pretty terrible day for news. Not only was Trump elected US president, but an accident involving a tram in Croydon, south London, resulted in the deaths of seven people and many others injured. It was the first time that a tram passenger had been killed in an accident in Britain since 1959, although there were no tram lines in Britain between 1962 and 1994 with the exception of Blackpool and a handful of heritage operations.

The incident is under investigation, but we know that the tram derailed and flipped on its side whilst travelling around a sharp curve. The speed limit on the curve was 20 km/h (12 mph) and initial findings by the Rail Accident Investigation Branch suggest that the tram was travelling significantly faster than this at the time. And a public Facebook post from last week suggests that this wasn’t the first time that a tram has been driven faster than it should have been across that junction. I have no doubt that this will be another line of enquiry into what caused the accident. We also know that the driver of the tram has been arrested on suspicion of manslaughter and subsequently bailed by police.

Trams, especially the second and third generation systems now in use on British tramways, are very safe – as mentioned, this is the first time that passengers have been killed since Manchester’s Metrolink opened in 1994. They’re certainly safer than catching a bus or driving.

However, trams do not have the same amount of safety systems that trains have, at least in the UK. The majority of trams are driven like buses, i.e. using line of sight. If the path ahead is clear, then the driver may proceed, although signals are provided on sections shared with road users. Interestingly, Manchester Metrolink used to have lineside signals for the sections that weren’t on streets, but these are being phased out now, to allow trams to travel closer together.

Trains, on the other hand, are all fitted with Train Protection & Warning System (in the UK),  which prevent trains from passing red signals and from passing yellow signals at high speeds. TPWS was rolled out following the Ladbrooke Grove and Southall rail disasters in the 1990s where trains collided after passing red signals, resulting in many deaths and injuries.

Perhaps, where trams are due to approach a section with such a tight speed restriction, there should be some similar system that automatically applies the brakes if the trams are going too fast. But any safety system will cost money to implement, and may not be worth it. After all, we’ve had 22 years of modern tram systems in the UK without any passenger deaths. The Croydon system itself dates from 2000, and whilst there have been some minor incidents, the trams have clocked up thousands of miles without any passenger deaths until now.

The reports into the incident will follow over the next few weeks and months, and I will read their conclusions with interest. For now, my sympathies are with the families of those who lost loved ones on Wednesday.

This blog post was originally entitled ‘Tram-gedy’, but has been changed – a pun was not really appropriate.

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