ULTra ("Urban Light Transport") is a personal rapid transit system from Advanced Transport Systems (ATS), a company based in Cardiff, Wales. The system was conceived by Martin Lowson and his design team, Lowson having put £10 million into the project. There are not yet any commercial installations of ULTra, but a pilot project is under construction at London's Heathrow Airport,[1] being developed by BAA in partnership with ATS.[2] Running tests began in December 2008, and the planned start of operation is in late Spring 2010.[3]
To reduce fabrication costs, the ULTra system uses largely off-the-shelf technologies, such as rubber tyres running on an open guideway. This approach has resulted in a system that ATS believes to be more economical than a design requiring custom technology. The company reports that the total cost of the system (vehicles, infrastructure and control systems) is between £3 million and £5 million per km of track.[4]
Advanced Transport Systems Ltd has twice been awarded funding from the UK National Endowment for Science, Technology and the Arts (NESTA).[5] Much of the original research on ULTra was done by the Aerospace Engineering department at the University of Bristol during the 1990s.
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Background
Past PRT designs
One of the key determinants in the passenger capacity of a mass transit system is its "headway", the distance between vehicles along the route. Vehicles that take a long time to start or stop require large distances between them for safety, which reduces the capacity of the lines. In the case of a conventional metro system (subway), the difficultly in seeing trains in front puts a further limit on the spacing. In order for a metro to carry large numbers of passengers, the individual trains have to have very large capacities. This demands larger cars, heavier rail systems to carry them, larger stations to load them, and extensive safety and scheduling systems to operate them effectively. These requirements lead to high capital costs.
On the other end of the scale, automobiles can be safely operated with very short headways on the order of two seconds. In spite of carrying less than two passengers, on average, road capacity is generally fairly high as a result of these short inter-vehicle spacings. Roads can be built much lighter, often laying crushed rock and asphalt on lightly prepared ground, and any open space can serve as a "station". This also makes the system efficient; during times of low demand, roads simply carry less cars, but a metro system generally still has to use full-sized trains, often running almost empty. For smaller cities, or suburbs of larger towns, a metro is less efficient than a road as energy is spent moving empty trains.
The personal rapid transit, or PRT, originally developed in the 1950s as a response to the need to move commuters in areas where the densities were too low to pay for the construction of a conventional metro system. Using automated guidance allowed headways to be shortened, often to an automobile-like two seconds, but in some cases to hundredths of a second with only centimetres between vehicles. This increases the route capacity, allowing the vehicles to become much smaller, which in turn would require simpler "tracks", smaller stations, and lowered capital costs as a result. Smaller towns and cities that could never hope to fund a conventional mass transit system could afford a PRT, and the concept generated intense interest.
Numerous PRT systems were designed in the late 1960s and early 1970s, many as a result of the publication of the highly influential HUD Reports. In general, these systems intended to use small four to six passenger vehicles, but most evolved to larger designs over time (see Alden staRRcar). As they did so, vehicles and tracks grew heavier, capital costs rose, and interest dropped. In the end, only one production PRT system was ever installed, the Morgantown PRT, a government-funded demonstration system to prove the concept. Originally derided as a white elephant, the Morgantown system has since proven itself both reliable and relatively low-cost.
ULTra
In the time since the Morgantown system was installed, general technological improvements have led to a number of ways to lower the cost of implementing a PRT system. One of the simplest, but most profound, was the development of more efficient, reliable and quick charging battery systems. Older PRT systems used electricity fed from track-side conductors in a fashion similar to a conventional subway, but these can be eliminated in favor of batteries that quickly charge up at stations or small charging strips along the route. Another change is the moving of the guidance logic from centralized computers to on-board systems of dramatically improved performance, allowing the vehicles to steer and switch themselves between routes on their own. This eliminates the need for a track-mounted guiderail able to steer the vehicle (see, for instance, the Ford ACT). Together, these changes mean the vehicle no longer needs strong mechanical contact with the guideway, which can be dramatically reduced in complexity.
In the case of ULTra, the guideway can consist of as little as two parallel rows of concrete barriers, similar to the bumpers found in a parking lot. The vehicle uses these for fine guidance only; it is able to steer itself around curves by following the barriers passively. No "switching" is required on the track either, as the vehicles can make their own turns between routes based on an internal map. Since the vehicles are battery powered, there's no need for electrification along the track, instead the vehicles recharge when parked at the stations. As a result, the trackway is similar in complexity to a conventional road surface - a light-duty one as the vehicles will not vary in weight to the extent of a tractor-trailer. Even the stations are greatly simplified; in the case of ground-level tracks, the lack of any substantial infrastructure means the vehicles can stop at any curb.
For all of these reasons, the capital costs of the ULTra system are dramatically reduced compared to older systems. A 1980's Canadian estimate places the price of a conventional underground subway system at $75 to $80 million a kilometer,[6] about $190 million CAD in 2008 dollars.[7] The Morgantown PRT came in well over-budget and has a demonstrated cost of just over $9 million a kilometer in 1979 USD, about $26 million in 2008 dollars.[8] Expansion plans from just after 2000 puts the costs of additional track at $10 to $15 million a mile. However, ATS estimates that an ULTra system can be installed, including vehicles and stations, for £3 to £5 million per km of track,[4] about $5 to $8 in 2009 US dollars. This cost includes extensive sections using elevated guideways, which are much more expensive than at-grade versions.
System description
Vehicles
The electric-powered vehicles have four seats, can carry 500 kg payload, and are designed to travel at 40 km/h (25 mph) at grades up to 20%, although the company suggests limiting operating routes to 10% for passenger comfort. It is powered by a battery pack providing an average 2 kW of power and adding 8% to the gross weight of the vehicle. Other specifications include a 5 m turning radius, an energy requirement of 0.55 MJ/passenger-km, and running noise levels of 35 dBA at 21.6 km/h and at a distance of 10 m. The vehicles can accommodate wheelchairs, shopping trolleys and other luggage in addition to the passengers.
ATS have also developed designs for a freight version of the vehicle. This has the same external appearance as the passenger version, but its entire internal space is adapted to host a cargo capsule.
Test track
The 1 km ULTra test track was launched in January 2002. The $4 million funding for the test track came from various sources in the UK government. One electric vehicle was demonstrated running at speeds of less than 25 mph. Accurate stopping was demonstrated and the vehicle ascended and descended a steep grade. A single, rudimentary ground level station was shown.
Most of the test track guideway is at ground level. It is stated that in a commercial application, 90% or more of the guideway might have to be elevated. This elevated guideway is about 1.5 m wide. According to an ATS study of a hypothetical city-based installation, consisting of 19.8 km of guideway (89% of it elevated), the total cost of ULTra track and associated civil engineering works is estimated to be £2.9M/km ($8.7M/mi). Per-station costs were estimated to be £0.48M ($0.89M). Vehicle costs were not considered in this study.[9]
Heathrow Terminal 5
The Heathrow Terminal 5 project includes a 3.9 kilometres (2.4 mi) ULTra PRT system expected to use 21 vehicles. It will connect the new terminal to the N3 long-term car park, just north of the airport.[10] The developers expect that users will wait an average of around 12 seconds with 95% of passengers waiting for less than one minute for their private pod which will travel up to 40 km/h (25 mph). If the pilot project is successful, BAA indicated that they will extend the service throughout the airport and to nearby hotels using 400 pods.[11]
Construction of the guideway was completed in October 2008.[12] With completion of the guideway, fit out of the stations and track can begin. The operators now expect the system to open to airport users in late spring of 2010.
References
Notes
- ^ "BAA signs agreement to develop innovative transport system" BAA plc Press Release - 20 October 2005
- ^ "World first for Terminal 5" Heathrow Community News - Spring 2007
- ^ "ULTra PRT - Latest Schedule" (html). ATS ULTra. 2009. http://www.ultraprt.com/cms/index.php?page=latest-schedule. Retrieved 02 September 2009.
- ^ a b "ULTra FAQ", ULTra PRT site
- ^ "Martin Lowson, Advanced Transport Systems Ltd awardee profile" NESTA milestones
- ^ Litvak & Maule, pg. 104 – the first mention puts it at $80 million, but the very next page puts it at $75
- ^ Using the Bank of Canada inflation calculator
- ^ Cite error: Invalid
<ref>tag; no text was provided for refs nameduscalc; see Help:Cite error. - ^ Kerr & James
- ^ Rodgers, Lucy (2007-12-18). "Are driverless pods the future?". BBC News online. http://news.bbc.co.uk/1/hi/uk/7148731.stm. Retrieved 2007-12-18.
- ^ Guardian Unlimited Welcome to the transport of tomorrow
- ^ "Heathrow rapid transit guideway construction completed". Transport Briefing. 2008-10-23. http://www.transportbriefing.co.uk/story.php?id=5275. Retrieved 2008-10-24.
Bibliography
- Isaiah Litvak and Christopher Maule, "The Light-Rapid Comfortable (LRC) Train and the Intermediate Capacity Transit System (ICTS): Two Case Studies of Innovation in the Urban Transportation Equipment Manufacturing Industry", University of Toronto/York University Joint Program in Transportation, 1982
- A.D. Kerr, P.A. James (Ove Arup and Partners), C.V. Cook, A.P. Craig (ATS Ltd.) (May 2005), Infrastructure Cost Comparisons for PRT and APM, ASCE 10th International Conference on Automated People Movers
External links
- www.atsltd.co.uk
- "Cardiff County Council Environmental Scrutiny Committee Meeting held 25 June 2002"
- Test track aerial image
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