Inside Heathrow's pod cars

7 min read

Could the introduction of ‘pod cars’ at Heathrow Airport herald a new era for urban transport in the UK?

Seventy years ago, the UK was criss-crossed with a comprehensive and popular network of trams and railways that would seem staggering to today’s public transport users.

It was in some respects the perfect model for an integrated urban transport system. But in the face of the rising popularity of the car, we shut much of it down. It seems unbelievable that we turned our back on it, but by the early 1960s most of Britain’s trams had been scrapped and after the Beeching report of 1963 put paid to many of our local lines, our dependence on the car was complete.

But as the UK’s roads become increasingly congested and the clamour to find more planet-friendly modes of transit grows louder by the day, there are signs that the tide may finally be turning.

Light rail actually began making its tentative comeback in the 1980s. Today, Croydon, Birmingham, Manchester, Sheffield, Newcastle, Nottingham and Blackpool (the only town to retain a Victorian Tramway) all boast busy tram networks, and with similar systems proposed for Edinburgh, Bath and Leeds, the case is building to roll back the years.

One of the most promising signs of this urban transport renaissance is quietly taking shape in Yorkshire, where the Department for Transport (DfT), Network Rail and train operator Northern Rail are drawing up plans for a trial of tram-trains, versatile vehicles that can run on both conventional rail tracks and city-centre tram lines.

From next year, five — as yet unspecified — vehicles will replace conventional trains on the 37-mile-long Penistone line that runs between Huddersfield and Sheffield. If successful, the plan is to then link the line up with Sheffield’s Super Tram system.

Already successfully applied in both the Netherlands and Germany, the system has a number of attractions. Lighter than conventional trains, tram-trains use less energy and have been demonstrated to produce less wear on tracks. Their low weight is also claimed to give them improved acceleration and braking characteristics that could shorten journey time.

It’s a tricky project that runs the risk of upsetting regular passengers while the estimated £15m of alterations to stations and infrastructure are made. But Barry Graham, business development officer at Northern Rail, believes it will be worth the effort. ‘The continental experience demonstrates the new journey opportunities that can be provided in a well thought through and executed system,’ he said, ‘we really do want to scope the on-street opportunities and get tram-trains to the point where they are regarded as a serious component for urban planning and urban transportation planning. We are increasingly of the view that the tram-train has the potential to change the face of transportation in the UK.’

It’s perhaps a small-scale project alongside the huge investments currently being ploughed into other areas of the UK’s rail network, but it’s nevertheless indicative that light rail is back on the radar of the UK’s transport planners. Indeed, talking recently to The Engineer (4-17 May), Network Rail’s chief executive, Iain Coucher, said: ‘We’re looking at new forms of innovation in terms of lighter-weight trains and how they can be used to provide more regionalised services — I’d expect to see more forms of technology in those areas. We’ve got to get passengers out of cars and on to trains.’

Meanwhile, an alternative vision of our urban transport future is taking shape at London’s Heathrow Airport, where the world’s first fleet of driverless taxis is about to begin operation.

Developed by Bristol’s Advanced Transport Systems, ULTra (which stands for Urban Light Transport) is the first commercial example of the Personal Rapid Transit (PRT) system, a concept that has long been a staple mode of transport in science-fiction but, until now, never quite made the leap into reality.

Users of the £25m service, which will open to the public later this year, will be able to travel from the car park to the Terminal 5 building onboard futuristic-looking battery-powered pod cars. Its developers believe that success at Heathrow could lead to further implementations up and down the UK.

Noiselessly whizzing at up to 25mph along 1.5m-wide tracks that sweep from ground level to elevated guideways, the 820kg, four-seater pods are driven by 7kW AC drive motors and powered by four 45Ah lead-acid batteries. The system’s average energy usage is 0.59MJ per passenger km, making it around 70 per cent more efficient than a car. During a typical operation, passengers will enter one of the station’s many berths and use a smart-card-based system to select their destination. A vehicle is then assigned to the passenger and takes them non-stop to their destination by the best available route.

Once allocated a route by the central control system, each vehicle exploits telematics and IT technology developed elsewhere in the automotive industry to operate relatively autonomously. For instance, ultrasonic and laser sensors embedded around the outside of the vehicle read indentations on the sides of the track and, enabling the vehicle to know its exact position both laterally and longitudinally.

While some passengers might be concerned at the prospect of hopping aboard a car without a driver, Philip Griffiths, one of the engineers involved in the project, claimed that ULTra is safer than most other forms of transport.

Griffiths is chief engineer at UK transportation specialist ARRK R&D, which has designed and developed the 19 pods that will be used at Heathrow. He claimed that in four years of testing on the ATS test track in Cardiff there hasn’t been a single failure. ‘The beauty of the system is that you control every single aspect of the duty cycle — you control how fast it accelerates away and you know exactly what the braking characteristics are on a corner.’

Griffiths added that the system has been developed to cope with pretty much anything the British weather can throw at it. Complex aerodynamic simulations have confirmed its performance in side-winds, while a fleet of heavily instrumented survey and recovery vehicles — also developed by ARRK — are constantly on alert to remove obstacles or ice from the track.

And despite its high-tech credentials, the system is perhaps less expensive than one would expect. Indeed, Griffiths believes its relatively low cost is one of the factors that attracted the interest of Heathrow operator BAA. ‘The average bus runs with 12 people, which you need to run with a driver and to a schedule. This is a purely on-demand system. And the infrastructure costs are massively reduced compared to light rail and new roads.’ He added that the prefabricated steel structure used for the elevated section of the Heathrow ULTra system was erected in around three nights.

One of the reasons for this is that, unlike conventional bridges or elevated sections of road, the load carried by the ULTra guideways can be intelligently controlled and monitored. ‘You’re working in a very controlled environment and you control exactly how many vehicles are on it — so you’re not dealing with 40-tonne trucks in traffic jams,’ Griffiths explained.

If this summer’s trial is a success, BAA has said that the system could be rolled out across the entire airport, a deployment that would require around 350 vehicles and 50 stations.

But while a full roll-out would be a massive coup for PRT, the ambitions for ULTra stretch way beyond Heathrow. Indeed, its developers believe it could trigger nothing short of an urban transport revolution. ‘ULTra is designed to extract people out of their cars by providing a better and more environmentally friendly service than the car,’ said ATS founder Martin Lowson, who developed the concept while Sir George White professor of aerospace engineering at the University of Bristol. Commenting on the system’s urban potential, ARKK’s Griffiths added: ‘The analogy is a horizontal lift — it could negate the need for car parking around supermarkets, you could move supermarkets back into the centre of towns.’

Though there are currently no plans for an urban roll-out, there are ongoing studies for Bath and Daventry, and Lowson believes that many more local authorities are waiting to see how the current application rolls out before taking their interest to the next level.

But while the Heathrow application will provide a both compelling shop window and stern test of the system’s potential, success here is no guarantee that the system will be an automatic success in an urban setting.

Indeed, Dr Paul Firmin of Leeds University’s Institute for Transport Studies is worried that lack of attention to the likely social and environmental impact of PRT systems could prevent the technology from fulfilling its potential.

Though excited by the Heathrow application, which will, he believes, go down well with the adventurous types preparing to make long overseas journeys, Firmin raised concerns about the issues that will arise if the system is taken outside the controlled and relatively sanitised environment of an airport.

‘Lots of work has been done on the technical issues, the operational side and the economics side but very little on the social acceptance, which has a big impact for the potential of the system in urban areas, and that could dictate whether the system is successful or not.’

Firmin is particularly concerned that an urban PRT system would become a magnet for criminal and anti-social behaviour. ‘I think it’s going to bring a whole new raft of crime-waves — things that we don’t yet experience. I’m particularly concerned about the issue of what I term “pod lurking”, where people in the pods spring out at people unsuspecting in isolated locations or wait for people to disembark from pods late at night.’

Another concern is the potentially dehumanising effect of a public transport system that places its users in what is, in effect, a private space. Firmin sees parallels with the development of high-rise social housing in the 1960s. ‘The planners and architects thought it was a great solution, they went ahead and did it, and now of course we’re ripping the things down, because it dehumanised people. I can see parallels with PRT.’

Despite these concerns Firmin does see great urban potential for PRT systems. ‘Now is the time that PRT could happen,’ he added, ‘we are all being asked to get out of our cars and if there was a proper public transport system — which potentially PRT could be — then we’re getting a step towards true sustainability.’

But Firmin also believes that PRT developers must not lose sight of the social context of their technology. ‘I’ve seen lots and lots of systems that work beautifully in computer simulations — we’ve now got to take those concepts through to reality — and therefore social cultures and public acceptance need to be considered, modelling issues need to consider the human dynamics element. There needs to be some social engineering injected into PRT research and design. I don’t see it at the moment, it’s sadly lacking, and because of this it will be a system that will not fulfil its potential.’

With a growing emphasis on new technology and expanded public transport links, Firmin’s call to consider the social context of big engineering projects is a timely one that need not simply apply to concepts such as PRT. ‘I’m a regular bus user — very often my bus stop is wrecked, I’ve been on buses that have bricks thrown at them, this is all going to happen with these pods. We need to engineer and design in safety and security technology. At the moment they’re solving technical problems with technical solutions, now you need to solve social problems with technical solutions.’