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Is the world ready for driverless trams?

Bombardier's ODAS system uses multiple inputs to scan the track and environment ahead. Courtesy of Bombardier.

On 9 November 2016, a tram overturned on the corner at Sandilands junction, Croydon. Of the 60 passengers onboard, seven died and 51 were hospitalised. The tram was travelling at 70km/h (43.5mph); the speed limit is 20km/h (12.5mph). The driver was arrested and tested for alcohol and drugs but has been released on bail until May.

The UK’s Rail Accident Investigation Branch (RAIB) is investigating, but in an interim report on 16 November it said: “The RAIB has undertaken a survey of the track in the vicinity of the derailment and will be reviewing the findings from the survey in due course. At this stage, no evidence has been found of any track defects, or obstructions on the track, that could have contributed to the derailment.”

As the first fatal tram crash in the UK since January 1959, and the first amongst the nation’s ‘second-generation’ systems, it has raised a number of debates about the safety of trams and light rail. The wider media has raised questions such as: Would self-driving trams be safer? And if so, could this be the end of the tram drivers’ GBP36 000 (EUR43 000) a year profession?

The first steps

Mobile telematics are evolving at a rapid pace: technology in the automotive market currently allows a 4G-enabled vehicle to automatically apply the brakes at 1.4m (4.5ft). With 5G this will reduce to 0.02m (one inch) – 54 times better.

Bombardier and Bosch Engineering have already taken the first baby steps in the process of automation for trams and LRVs. Bombardier first revealed its Obstacle Detection Assistance System in 2013, received homologation from German authorities in summer 2015 and launched it into full passenger service with Frankfurt-Am-Main operator Verkehrsgesellschaft Frankfurt (VGF) in August 2015.

Stereovision cameras scan the track and give audible and visual warnings of obstacles; if no action is taken then the brakes are applied. Tests of the technology are also underway in Berlin, Marseille and Cologne.

Bosch’s driver assistance technology uses a mid-range radar sensor, rail control unit and multi-purpose camera derived from its considerable experience in the automotive sector. Operating independently of weather and light conditions, the sensor recognises potential obstacles up to 80m away and, taking the vehicle’s speed into consideration, transmits data in real-time to the control unit.

The system comes in two forms. The first alerts the driver via customisable audible and visual warnings. The second goes a stage further and can automatically apply the tram’s brakes in the event of driver inaction – although the driver can still intervene. Components on both systems have been designed to be as compact as possible to make retrofitting to any light rail vehicle easy.

After evaluating both innovations, VGF is also retrofitting the Bosch system to its older Düwag fleet dating from the 1990s.

Dealing with busy streets

CRITICAL Software provides software for safety-critical business tasks.

Business Development Manager Luis Gargaté believes trams are easier to automate than cars, but harder than trains. He explained: “Most automatic vehicles, like those in airports and underground, run within closed-off tunnels which create a very safe, obstruction-free environment. The computers controlling them don’t have to deal with the unexpected behaviour of other vehicles, wayward pedestrians, adverse weather and other factors that any vehicle travelling on a public road, or even an open track, would likely encounter. But trams running on our streets would have to deal with the same problems driverless cars will have to overcome.

“The technology available, although it’s progressing admirably, isn’t capable of dealing with the complexity just yet. This might mean that once driverless vehicle technology has reached a certain level of maturity, and is trusted by society, automated trams might be quicker to roll out into the public domain than driverless cars.”

UK Delivery Manager Kevin Gale explained what improvements are needed before this can happen, however: “Creating a more controlled environment for the trams to run within would ease the pressure on the controlling technology, but that’s a difficult ask. Our streets are busy, people will still make judgements that computers cannot predict and natural factors such as earthquakes and flooding will also play a role.

“Once we enter a fully autonomous setting – removing the potential for human error altogether – then we could be looking at roads that are totally safe. Mixing human-controlled vehicles with automatic ones is tougher to work around. Our world is changing though and ‘smart cities’ are beginning to appear. These utilise huge networks of smart devices and could play a big role in improving road safety and traffic efficiency.”

The Docklands Light Railway (DLR) has featured driverless operation ever since it opened in 1987. There is a human onboard (‘Passenger Service Agents’), but their role is to check tickets, assist passengers and help in the event of an emergency. An older example is the invention of the autopilot in 1914, just 11 years after the first manned flight.

The DLR has had two (non-fatal) derailments, one with the computer in charge, the other with a human on duty. The first was at Deptford Bridge station on 4 April 2008. The train hit a steel drilling jig left on the track following engineering works that morning; the first bogie’s second axle derailed, the train stopping 88m away. Human error was a factor in this incident and the RIAB report made safety recommendations regarding work and checking procedures.

The second was near West India Quay station on 10 March 2009. The train was trailing when the points were not properly set; the driver had not noticed the points were set to reverse (the point position indicator was unlit), nor did he brake. The control centre controller did not know the exact location of the train or follow the correct emergency protocol.

Other fatalities on the system have occurred mainly through suicide attempts, although it is difficult to assess whether either a human driver or computer could have prevented these.

James Smith, Head of Communications at vehicle safety specialist Thatcham Research, explained how autonomous vehicles work: “Utilising onboard sensors – normally radars, cameras and lasers combined with local mapping – a vehicle builds a picture around situational awareness; where it is and how fast and in what direction it’s travelling. Using a pre-defined route the vehicle guides itself whilst monitoring other road users using onboard mapping knowledge to follow a path. The sensors constantly evaluate other traffic and conditions to ensure collisions are avoided whilst the mapping will control vehicle speeds and routing.

“Think of lifts and the Docklands Light Railway, neither of which have drivers. Both have defined and carefully controlled paths. The Parking Pods at Heathrow are similar but can vary their route within controlled parameters. Road traffic is much too complicated to allow them to interact.

“Laws also prevent their use. The Vienna convention says that road vehicles must have a driver and local UK laws (the Road Traffic Act) prevent it. Both of these are in the process of being amended.”

Man vs. machine

In June 2016, Dublin became the first city to call for full tram automation.

A 12-day tram drivers’ strike led to Fine Gael Councillor Paddy Smyth proposing the motion: “Given the disruption, both civic and economic, caused by the Luas drivers’ strikes in recent months, this committee calls on the new Minister for Transport, the National Transport Authority, Transport Infrastructure Ireland and Transdev, to future-proof all new Luas rolling stock so that it is capable of being fitted with self-driving software… it is not a question of if we automate, but rather when we automate.”

The motion was passed by Dublin City Council’s Transport Committee.

Owen Reidy, Divisional Organiser for SIPTU, Ireland’s largest trade union, called this a “hare-brained crazy scheme”, pointing out there had been one dispute since the no-strike clause was removed in 2012.

Yet Smyth insisted that, in the immediate term at least, tram drivers “will not be replaced by an automaton”, telling the Council: “I doubt there is a single person in this chamber who believes that in 50 years’ time humans will be driving these trams. The only thing industrial disputes of this nature achieve is to hasten the inevitable.”

Most British tram drivers belong to train drivers’ union ASLEF, which is sceptical
about driverless technology. General Secretary Mick Whelan said: “We know from experience that trams, unless they are on dedicated and exclusive tracks, need to be manned because of other transport users and the vagaries of pedestrian behaviour. This is particularly the case in our major cities, and those with a large tourist base, and we have yet to see a system we would be willing to endorse.”

Andrew Braddock, Chair of the UKTram Promotions Group, thinks automation would save little: “It is difficult to see how trams running in the street could be automated, though developments with other self-driving vehicles may hold the key. At the moment, it seems likely that automated trams would have to travel much more slowly than their human-driven counterparts. That would significantly increase capital costs.”

He sympathised with the unions’ perspective, however: “It seems reasonable to question the impact on labour markets of increasing automation in all spheres. Where will people earn a living in future?”

So, in theory at least, every mass transit driver could lose their job to computers in the next few decades as cars, trains, ships, even planes, could be completely automated. But it doesn’t end there as CRITICAL Software foresees a scenario where maintenance workers will also be replaced in the future, as Gale explains: “Automatic vehicles will need to be maintained to a high standard throughout their useful life and this requires systems to monitor the status of various (and numerous) components. There are clear advantages for automating vehicle checks, removing human error and improving availability.”

The Internet of Things will allow trams to self-monitor, he contends: “Automated vehicles are complex by nature and need to be trusted by their users. Systems are developing to include onboard monitoring equipment, essentially providing ‘self-test’ diagnostic information which is relayed back to a central maintenance unit. Combining autonomous vehicles with automatic monitoring will definitely reduce costs.

“For example, operators rely on exhaustive checks carried out by engineers which makes efficient asset management harder, plus any mistakes or errors can be exceedingly costly when it comes to public services. Automatic monitoring technology reduces staff costs, asset management costs and costs incurred through human error.

“As these rail-tested systems already exist, extending them to cover trams won’t be too expensive either. Once we have the right technology and infrastructure in place, accidents would become a rarity.”

Gargaté was then asked the tricky question as to who would make the safer driver, a human or a computer: “When the technology is mature enough, a computer-controlled vehicle will be safer. Even if faults arise in the control system, they can be systematically minimised by following strict development processes. But as we’ve only just begun to test the performance of driverless vehicles, a human driver is currently still safer.

“Our roads present an extremely complex environment for computers to manage, but eventually automatic vehicles of all kinds will become mobile offices, workstations or meeting hubs. They could facilitate a more productive population and so might contribute to a richer economy.”

To conclude, tram drivers can be replaced more easily than car drivers, there just needs to be the political will. This latest accident may provide the impetus, and pressure for it to happen. If so, tram drivers will soon go the way of the lift attendant.

Article as originally appeared in TAUT 950 (February 2017).