In the Northern Hemisphere at this time of year, the leaf fall season has traditionally posed major problems for railways, and it exposes the crucial interface between train operation and infrastructure for all to see.
The slippery properties of compressed leaf mulch on railheads are well known and – these days – understood. The primary risk is undoubtedly a train losing adhesion as it brakes for a signal check and passing the signal at danger and out of control. But another more insidious problem occurs when a buildup of mulch insulates the rails and prevents track circuits from operating effectively. This can give rise to trains disappearing from signalling displays or simply not registering that they have passed a signal. The failsafe nature of signalling – that a train is not allowed into a section ahead unless it can be proved to be clear – means that mishaps are unlikely, but it adds another potential headache for rail operators.
Thankfully, with the problems well understood, the solutions seem to be working well this year with few indications of undue delay: a combination of defensive driving techniques, water cannons clearing railheads and proprietary solutions applied to rails are gradually defeating the problems caused by leaf fall. Increasing replacement of track circuits with axle counters is also undoubtedly having an effect in improving the reliability and consistency of train detection.
Sceptics may suggest that the obvious solution is to chop down all trees near operational railways but ownership and conservation issues make this a non-starter in most countries. The reality is that a combination of proactive infrastructure management to limit the causes and rapid reactive measures to target known ‘hotspots’ is the best most railways can hope for. On the evidence so far this year they appear to be doing a good job.
This month’s dreadful accident near Santiago de Compostela, Spain, has thrown rail safety into the spotlight again. As investigators seek to establish how a modern train derailed so catastrophically it is inevitable that attention from the wider media focusses on the onboard and lineside safety systems designed to limit the chances of incidents like these happening.
A train cab fitted with ERTMS equipment. Credit: Network Rail.
If, as is being widely reported, excessive speed was the major factor in the derailment, there will be calls for better signalling systems to prevent drivers speeding, and just as in the 19th century when a series of accidents prompted legislation in some countries demanding interlocking of signals and points, the technology exists and is proven in the real world, most notably in the form of European Rail Traffic Management System (ERTMS). If speed was a factor at Santiago de Compostela, ERTMS would have prevented the train from exceeding the speed limit and intervened if the driver left braking too late. With the system already deployed on large parts of Spain’s high-speed rail network, it would be surprising if there weren’t calls for its immediate and widespread deployment across much of the conventional railway too.
Change of focus
This derailment really does transform the importance of ERTMS from a pan-European system aimed at enhancing interoperability to a service proven, off-the-shelf integrated signalling system with inbuilt Automatic Train Protection and overspeed prevention. New Zealand opted for ERTMS for these reasons on Auckland’s commuter network, where interoperability with other countries’ rail networks simply isn’t an issue. Other countries will now surely be considering ERTMS for its safety benefits over and above potential gains to be made in terms of capacity and interoperability.
In the past introducing new signalling systems was a ferociously expensive exercise with vast scope for disruption and unreliability. Today ERTMS is service proven and increasingly good value to install as more and more systems use it.
If the dreadful events at Santiago de Compostela are to have a legacy, the best of all would be to make it the last major rail accident caused by excessive speed, if indeed that is the cause.
The decision to fine a UK signaller £1,750 for his part in a fatal level crossing accident in 2010 once again raises the issue of how best to manage level (or for North American readers, grade) crossings safely. The UK track authority, Network Rail, was fined £450,000.
The accident was caused by the signaller raising the barriers of the level crossing as a train approached. The signaller claimed that a telephone call from a farmer seeking to cross his sheep over an occupation crossing disrupted his concentration.
Most level crossing accidents are caused by road users misusing the crossing – often on half-barrier crossings by weaving around the barriers. However, the human factor in this case surely emphasises the case for increased automation – doesn’t it?
While barrier activation is relatively easy to achieve via proximity devices such as treadles activated by approaching trains, preventing the barriers closing on vehicles or people is proving somewhat problematic. Although huge strides have been made in object detection systems, discerning the difference between, say, a football or a small animal such as a fox and a child or pushchair is proving worryingly inconsistent. (Larger objects such as road vehicles are, admittedly, much easier to detect). Monitoring level crossings via CCTV has long been used but is a partial solution at best – particularly given that the operator’s attention will invariably be divided between a number of screens.
So what is the best solution for ensuring the safety of road and rail users at level crossings? Intelligentsignalling.com is interested to hear your views….
Level crossings are one of the major risks to rail safety.
A major new level (grade) crossing safety system is being installed by Queensland Rail, Australia, in a bid to cut the number of accidents at high-risk sites.
Called Valet, it uses flashing lights embedded in the road to alert motorists to oncoming trains, mimicking the effect of airport taxiways. With level crossings one of the main risks to rail safety, this could be an important innovation in Queensland. The diagram below shows how it works.
Queensland Rai’s Valet system promises to alert motorists to oncoming trains earlier.