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Are driverless trains the future?

Paula-Marie Brown, head of transport at the Institution of Engineering and Technology (IET), discusses the impending reality of driverless trains. 

The recent strike that affected London Underground highlighted how technology is changing the face of our railway networks.

Many readers will have quite happily travelled in a driverless (i.e. autonomous) system. Maybe it wasn’t comprised of multiple carriages and it had a limited number of destinations, but once inside with the doors closed, you were under the protection of an autonomous system.

Forgotten drivers

What functions do drivers perform in a modern railway? As far back as 1988, Tony Hawker presented a paper at an Institution of Railway Signalling Engineers event entitled ‘Have we forgotten the driver?’ The focus of the paper was that making signalling systems more efficient (simplifying layouts, reversible operation etc.) meant that, whilst systems were safe when the signalling system was operating correctly, it became more and more difficult to drive the train manually under degraded conditions. That was with a driver in the cab.

To take the scenario a stage further, should we forget the driver? If so, what happens under degraded modes conditions? However, an examination is required of the skills needed of a driver on a day-to-day basis (in normal and degraded conditions). Once that is understood, the impact on risk of removing the driver can be better debated.

What a driver does under normal conditions will depend on the level of automation of the train. In a manually driven train, in general they manage speed to keep it at or below a safe level and by observing and reacting to the signals and keep a safe separation between the trains as well as observing the track ahead for obstructions.

On a number of modern systems (mostly metros) there are functions where technology already manages the safety of the train around the railway network. Systems have been around for many years that can easily manage and monitor the speed to a correct profile. Additionally, other systems manage the separation between trains and the stopping of trains at the correct place in platforms and in heavy traffic areas; the electronic system can manage the throughput of trains much more effectively than a driver can. So is the driver more of a hindrance than a help?

Coping on the front line

There are two issues to consider in support of the driver. Firstly, the driver is also the on-board front line mechanic for the train and has all sorts of overrides and bypasses which ensure that virtually all train failures can be overcome – even if the train has to proceed at very low speeds.

Secondly, the driver is human and able to adapt to each unusual situation. A transport system is there to move people. By their very nature, people are random in their reactions to the events around them. When there is a perturbation, a driver can cope with this (indeed is trained to cope); we may forecast a computer system able to adapt to this degree, but not yet.

There are also downsides with (too much) automation. Valid concerns have been raised that if the driver lets the automated system control the train for too much of the time, the driver will lose the ‘feel’ of the train and thus the ability to effectively drive the train when the system is operating in degraded mode.

In fact, it is common amongst metro operators to ensure that the driver should operate the train manually for a period of time. For one operator, the figure of 30% of the time in manual was tried and whilst it is appreciated how necessary it was for the driver to retain the competence to drive the train, the 30% figure meant that in a lot of cases this manual driving had a negative effect on the train performance, which then impacted on headways. Ultimately the system was unable to maintain the timetables. The 30% figure, whilst desirable, was then revised down quite significantly. On the Jubilee Line, the trains are only driven manually into the depot and that is really to react to events that may be occurring on the ground (shunters and depot staff walking in the area).

More relevant to mainline trains is the driver’s ability to sound an audible warning to announce the presence of the train – an essential safety function when staff are working on the line.

Ready or not?

Are the railways ready for autonomous vehicles? They do exist in some applications, mostly in low speed people movers on dedicated and protected infrastructure. There are some fully automatic metros, such as the DLR in the UK and in Denmark the Copenhagen lines Ml & M2.  However, there are no mainline railways in the world that are completely automated and without a driver. But the Klang Valley Metro in Malaysia is migrating towards driverless (non-attended) operation.

The UK will have one of the few main lines with ATO when Thameslink and Crossrail are commissioned, but that is a few years away. The step to driverless and full automation is still considered a  long way off for main line trains, unless they are specially designed for that purpose (in particular the infrastructure) and will require maximum protection to reduce access from errant people and vehicles.

So, in places like Britain with a massive legacy rail infrastructure it may be this very legacy which constrains us as we judge ourselves against those new build railways which continue to be constructed and for which driver-less is more about ‘why not?’ rather than ‘why?’