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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.