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2013-06-05 12:59:16
Transport: New train technologies are less visible and spread less quickly than improvements to cars or planes. But there is still plenty of innovation going on, and ideas are steadily making their way out onto the rails
Jun 1st 2013 |From the print edition
COMPARED with other modes of transport, train technology might seem to be progressing as slowly as a suburban commuter service rattling its way from one station to another. Automotive technology, by contrast, changes constantly: in the past decade satellite-navigation systems, hybrid power trains, proximity sensors and other innovations have proliferated. Each time you buy a new car, you will notice a host of new features. Progress is apparent in aircraft, too, with advances in in-flight entertainment and communication, fancy seats that turn into beds, and quieter and more efficient engines. Trains, meanwhile, appear to have changed a lot less.
This comparison is not entirely fair. For one thing, people buy their own cars, so they pay more attention to automotive innovation. Carmakers are engaged in a constant arms race, trumpeting new features as a way to differentiate their products. Nobody buys their own trains. Similarly, air passengers have a choice of competing airlines and are far more likely to be aware of the merits of rival fleets than they are of different types of train. In addition, notes Paul Priestman of Priestmangoode, a design consultancy that specialises in transport, trains have longer lives, so technology takes longer to become widespread. The planning horizon for one rail project he is working on extends to 2050. You have to think about longevity, whereas the car industry wants you to buy a new car in two years, he says.
Yet there is no shortage of new ideas, and they are steadily making their way out onto the rails. Better technologies are delivering everything from improved traction, braking and route-planning to sleek levitating trains designed to glide on air at an astounding 500kph (310mph). Energy-efficiency and safety are up, and derailments are down. There are schemes to transfer electrical energy from braking trains into local power grids, and even more radical plans for moving platforms that dock with high-speed trains.
For proponents of rail transport, such developments strengthen the political and economic case for favouring trains over roads or short-haul air travel. In 2011 a European Commission roadmap document on transport strategy called for a trebling of high-speed rail capacity in Europe, and further investment in urban networks, with the goal of halving the use of fossil-fuel-powered cars in cities within two decades. That seems optimistic. But high oil prices, clogged roads and rising demand for passenger and freight capacity have prompted widespread talk of a rail renaissance which will accelerate the adoption of new technologies.
To see how train technology is changing, start where the wheels meet the track. When rails are unevenly worn, damp, greasy or caked with decaying leaves, a wheel can temporarily lose full adhesion and start spinning faster than the train is moving. This slippage wastes energy and reduces pulling power. In recent years both diesel and electric trains have been fitted with computer systems that reduce power to a slipping wheel until it grabs the track. The computers also instruct sprayers to spew sand between wheels and rail when extra traction is needed. In difficult conditions, a locomotive may spray three tonnes of sand in just 24 hours.
Gaining traction
One new locomotive with such slip control , GE s PowerHaul, enabled a customer to lengthen its single-locomotive coal trains from 26 to 31 cars. Computerisation has also allowed an operator s actions to be automatically replicated by slave locomotives placed throughout the train. Using such distributed power is safer than yelling instructions into a radio for a locomotive operator at the end of the train, notes Carl Van Dyke of Oliver Wyman, a consultancy. It also makes trains of 200 or more cars possible. This largely explains how America, Canada and Mexico increased throughput on their networks by about 90% in the two decades to 2006, he says, even as net track in service decreased.
Brakes are also getting an upgrade. Stopping a train can take so long that locomotive-operators, also known as engineers, often have time to contemplate their fate before an impact. Your life races before you, says a former operator who, years ago in Alabama, helplessly watched as his freight train, its emergency brakes screeching, headed towards a stalled truck that ultimately managed to pull off the tracks in time. Stopping a train pulling a hundred cars at 80kph can require 2km of track. Road accidents take far more lives, but 1,239 people were killed in more than 2,300 railway accidents in 2011 in the European Union alone.
Much of the problem is that the faster a train s wheels are spinning, the hotter its brake shoes get when engaged. This reduces friction and hence braking power, a predicament known as heat fade . Moreover, nearly all trains power their brakes with compressed air. When switched on, air brakes activate car by car, from the locomotive to the back of the train. It can take more than two minutes for the signal to travel via air tubes to the last car.
Things have moved on a bit since the early 19th century
Modern trains have brawnier brake-shoe materials made with resins, elastomers and mineral fibres that can apply greater friction at higher temperatures with less judder , or shaking. Most important, brakes can now be triggered electronically, so that they can be activated on all cars at once. In America such electronically controlled pneumatic brakes were first used on a freight train just six years ago. Wiring up trains is expensive and, for now at least, makes it difficult to quickly swap cars in and out. But the technology is spreading, especially among mining firms that operate extremely long trains. This has reduced the number of runaway trains, which result when a downhill incline causes a train to accelerate beyond its braking capacity.
Networking software
Inadequate brakes are not the only cause of derailments, however. Train cars can also be thrown from the tracks if braking is too forceful. The more a train car weighs, the harder it pushes into the car in front of it during decelerations or downhill runs. Lighter cars are sometimes pushed up and off the tracks by heavier cars behind them. Railway engineers have long known that lighter cars should be placed at the end of trains, but cars of varying weight may be continually loaded, unloaded, added and removed along a route, altering the complex compression forces that can shove lighter cars off the tracks. Fortunately, software that simulates train dynamics can work out how best to load and sequence cars by analysing a given route.
A train might safely tow 8,000 tonnes behind an empty car on a straight track across a plain, but only 3,000 tonnes on curvy or sloping track. T V Rheinland Rail Sciences, a firm based in Atlanta, typically charges a few thousand dollars to analyse a route and up to $50,000 for a big network. Its software takes account of trade-offs: one possible train configuration might be slightly more stable but could produce a net increase in risk due to the odds of an accident during the more complex marshalling-yard work that would be required.
Such software is becoming more valuable thanks to technology that weighs moving trains. The trick involves welding a metal strain gauge , the size of a postage stamp, to the side of a rail. When passing wheels bend the rail slightly, changes in the gauge s electrical resistance reveal the car s weight. Roughly 200 such set-ups weigh passing rolling stock, for the most part in America, Australia, Canada and Mexico, says Gary Wolf, boss of T V Rheinland Rail Sciences. Most instantly report data via the web to railway operators who can then reconfigure a precarious train or adjust brake settings on cars. In the last five years accidents due to poor weight distribution have fallen dramatically, says Canada s Transportation Safety Board.
It is time to rethink the way railways work, which is stuck in a Victorian-era, pre-internet mindset.
Operators are trained to achieve golden runs on-time journeys that consume no more energy than the minimum physically required by each route, says Rodney Case, a former executive at France s SNCF rail company. On Paris-Marseille runs, for instance, France s fast TGV passenger trains use hilly terrain near Lyon to speed up and brake without consuming or wasting power. But passenger trains are short and light with uniformly distributed weight. For a long freight train to save fuel in this way, software is needed.
Norfolk Southern, an American rail operator, now pulls roughly one-sixth of its freight using locomotives equipped with route optimisation software. By crunching numbers on a train s weight distribution and a route s curves, grades and speed limits, the software, called Leader, can instruct operators on optimum accelerating and braking to minimise fuel costs. Installing the software and linking it wirelessly to back-office computers is expensive, says Coleman Lawrence, head of the company s 4,000-strong locomotive fleet. But the software cuts costs dramatically, reducing fuel consumption by about 5%. That is a big deal for a firm that spent $1.6 billion on diesel in 2012. Mr Lawrence reckons that by 2016 Norfolk Southern may be pulling half its freight with Leader-upgraded locomotives. A competing system sold by GE, Trip Optimizer, goes further and operates the throttle and brakes automatically.
Electric trains are also becoming more efficient, thanks in part to the use of new materials. Quebec s Bombardier is building monorail lines in Riyadh and S o Paulo for trains that are 25% lighter than traditional metropolitan rolling stock. A maker of aeroplanes as well as trains, Bombardier has designed its new Innovia Monorail 300 using weight-saving ideas borrowed from aerospace engineering. It will require 10% less energy per passenger than a traditional metro train, says Chris Field of Bombardier, who is overseeing the S o Paulo project. Weight reductions also mean that the monorail can be built on an elevated guideway for less than 60% of the cost of an elevated metro track.
Building track with overhead wires, known as catenary lines, to deliver power increases costs by about 10%, says Rainer Gruber, an electrification expert at Siemens, a German industrial giant. And yet a lot of such electrified track is being built, not least because high-speed trains use it. Within the EU, there are more than 6,800km of track capable of carrying trains at 200kph or faster, more than twice the amount there was in 2000. A further 2,127km of high-speed track are under construction in France, Germany and Spain. China expects to have 6,700km of track for trains that travel at 300kph or faster in less than two years. Other countries building high-speed lines include Algeria, Russia, Saudi Arabia, South Korea and Turkey.
Delivering power
The boom is partly due to electric trains efficiency. Accelerating a passenger train to 300kph and holding that speed for 100km costs only about 155 ($200) in Italy, says Valerio Recagno of D Appolonia, an Italian engineering consultancy. Moreover, regenerative brakes can recover much of a slowing train s kinetic energy and convert it back into electrical energy. This is hard to store, but can be transmitted across the grid if there is another train needing to accelerate within about 30km. And if there is not, Siemens has designed static frequency converters that turn electrical energy from braking trains into a sort that can be fed into the public grid and used to power homes and factories. This is now done in more than 20 locations in Germany, with a conversion loss of just 2%. Dr Gruber reckons that this is Siemens s most significant electrical innovation of the past decade.
Another new twist in railway electrification is being deployed in city centres. Overhead catenaries are unsightly, are dangerous in bad weather and can obstruct firefighters. But delivering power through a third rail also poses safety problems, particularly for trams running on city streets. So Alstom, a French engineering giant, has devised a system that uses a wireless signal, transmitted by a moving tram, to switch on the third rail only in the section covered by the tram. This increased the cost of building a 2km stretch of tramway in Bordeaux by about 8m. Even so, Alstom is building more lines using the technology in the French cities of Angers, Orl ans and Tours, as well as in Dubai.
A more radical approach to powering trains is that proposed by Russian Railways, which says it is designing a nuclear-powered train in conjunction with Rosatom, the state nuclear giant. Able to generate immense power, such a train could, in theory, move extremely fast or be used to supply power to a remote town or industrial site, using an on-board reactor similar to those found in nuclear submarines. Even if this nuclear-powered train takes to the rails, however, concern about the consequences of a derailment will probably impede widespread adoption.
A different sort of futuristic train propulsion is already hurtling passengers between Shanghai and its airport at 430kph. At that speed, it is hard to maintain smooth contact between a catenary and roof-mounted mechanical linkage, or pantograph, not to mention between wheels and track. Instead, the Shanghai Transrapid uses magnetic levitation. Described as electronically controlled flight by the North American Maglev Transport Institute, the system pushes maglev trains along a magnetic field powered by electricity surging through a guideway a few centimetres beneath them. Sensors measure this distance 300,000 times a second and adjust magnetic power accordingly.
A maglev train is akin to a surfboard riding a magnetic wave, says John Harding, formerly chief maglev scientist at America s Federal Railroad Administration. With most of the propulsion kit in the guideway, maglevs are so light they consume about a third less energy than fast conventional trains, according to ThyssenKrupp Transrapid, the German firm behind the Shanghai line. Proponents point out that maglevs can climb steep grades, accelerate more quickly and quietly than ordinary trains, and require less maintenance. In Japan construction has begun on a 290km line designed to carry maglevs between Tokyo and Nagoya at an unprecedented 500kph.
Even so, maglev may remain a niche technology, says Dr Harding. He reckons it costs at least 10% more to build maglev guideways than conventional tracks; other estimates are far higher. Another concern is that maglev railway projects are based on proprietary technology, making operators dangerously dependent on a single supplier, says Dagmar Blume of Bombardier, which dropped out of the consortium building the Shanghai line. On its website, ThyssenKrupp Transrapid boasts that it enjoys an exclusive market position to supply key maglev components.
A moving platform scheme proposed by Priestmangoode is more technologically ambitious than maglev trains even though it relies on conventional rails. Local trains would use side-by-side rails to roll alongside intercity trains and allow passengers to switch trains by stepping through docking bays. This set-up solves several problems, says Mr Priestman. Stopping high-speed trains wastes energy and time, so why not simply slow them down enough for a moving platform to pull alongside? This would also let high-speed trains skirt cities as moving platforms ferry passengers to and from the city centre.
A moving platform would allow transfers between local and intercity trains
If we can dock in space, why can t we do this? asks Mr Priestman. His wider aim is to encourage a rethinking of the way railways work, which is currently, he says, stuck in a Victorian-era, pre-internet mindset. He would like to see greater integration and easier transfers between different rail networks; the moving-platforms concept is the logical conclusion of this approach. If we are going to get people out of cars, and out of short-haul and long-haul air travel, railways are the way forward, he says. We just have to think differently about them.