To be a cyclist in London today requires the kind of spirit usually shown by those piloting experimental aircraft and one-man submarines. But with a little help from prefabrication and cutting-edge plastics, tomorrow might just be different …

Riders in the sky
Riders in the sky
Riders in the sky

The idea of elevated expressways in London brings to mind brutal concrete flyovers from the 1970s, choked with cars and juggernauts and shimmering in a haze of benzine and carbon monoxide. But overpasses do not have to be this way. Indeed, we could soon be treated to a touchy-feely 21st-century reinvention of the expressway – especially if Gerald Hodgson has anything to do with it.

Hodgson is the inventor of Scyway (pronounced “skyway”), a prefabricated, elevated expressway that he hopes will one day snake above London’s major roads. Of course, there have been many previous attempts to solve London’s transport problems. The difference here is that whereas most flyovers present just another venue for traffic jams, this expressway would be exclusively for the use of cyclists.

“The idea of the cycle expressway is that, as there is no more space for traffic in London or other major cities, the only answer is to go up,” Hodgson says. This is not an idle fantasy. Hodgson has teamed up with consultant White Young Green and contractor Fitzpatrick to prove that Scyway makes commercial sense and to work out suitable routes, including a link to the proposed Olympic zone. The main hurdle facing the consortium is to persuade Ken Livingstone, the mayor of London, to put money on the table. It might not be a fantasy, but there is still a steep hill to climb before it becomes a reality.

Currently, the capital is a frightening place for bike riders. As anyone who has tried to make it around Marble Arch will tell you, a cyclist’s life is in the hands of drivers taking a mobile phone call with one of them while they light up a cigarette with the other. And although riders can weave their way through clogged streets, traffic lights still slow them down. Hodgson says: “Figures show that 2% of people cycle in London but 20% cycle in other cities. It’s a matter of overcoming prejudices and providing the facilities.”

The plan is to make cycling safer and faster.

To this end, a 5.7 m high expressway would run down the middle of dual carriageways, supported on a single row of columns. On single carriageways, the columns would be placed on the edge of the pavement and the cycleway cantilevered over the road. Only cyclists would be allowed to use the routes, which they would be able to access from gently sloping ramps at major interchanges. Intermediate access stairs, with side ramps to enable people to push their bicycles as they climbed them, would be placed at intervals along the route. The expressway would have up to three lanes and a curved balustrade for safety. There is also the possibility that it would be covered, although this would make it more expensive, bulky and prone to vandalism.

If the scheme is to be affordable, it will have to be built in a hurry. Any company doing work that requires road closures is presented with a bill by The Highways Agency, calculated according to the length of time the road is closed. This makes a quick-fix, maintenance-free solution essential to the feasibility of the Scyways. And this is where prefabrication comes in. The expressway would be made from light fibre-reinforced plastic, which would enable sections up to 50 m long to be lifted into position using relatively small cranes (see “Paying with plastic”, overleaf). The sections would incorporate deck, balustrade and lighting – “as complete as they could possibly be off site”, says David Kendall, director of Cetec, White Young Green’s specialist structures division.

Hodgson reckons Scyway would cost about £2m a kilometre. “In relation to Crossrail, it’s a drop in the ocean,” he says. One way of lowering this cost is to route cables through a conduit within the deck and charge utilities for the service, which would mean that they wouldn’t have to dig up the road to carry out repairs. Hodgson is thinking big. “Our vision is a circular route around London following the boundary of the congestion charge zone and a series of radial routes coming in to that from residential areas,” he says. Scyway would stop at the boundary of the congestion charge zone because Hodgson thinks cycling in central London is more “pleasant” now the congestion charge has reduced traffic levels.

He also sees that planning could be a problem. “I personally think running it through central London is not on as there is a clear limit to its use near historic buildings,” he says. The first Scyway could link cycle routes at Mile End to the proposed Olympics zone at Stratford in east London. This would certainly prove popular with with its potential users, as it would mean that they would no longer have to negotiate a particularly unpleasant section of dual carriageway. It might also give added weight to London’s bid for the Olympics.

Would it attract new cyclists? Kendall certainly thinks so. “We’ve been in Sweden, Denmark, Germany and Holland recently. They are much better set up for cycling as they have cycleways everywhere, and the amount of people you see cycling is incredible – there are more bicycles than cars,” he says. The figures bear this out. Only 3% of journeys to work are made by bicycle in the UK, compared with 28% in Holland. He points out that none of those countries have better weather than the UK. Hills aren’t a barrier either because London is very flat, particularly east to west.

So the biggest challenge simply lies in convincing the powers-that-be. “There are many issues, such as planning, to resolve,” says Hodgson. “But all these things could be surmounted if the political will is there.” Given Ken Livingstone’s fondness for radical transport policies, it is tempting to think that London could be just the place to find that will.

Unfortunately, Scyway will not be coming to a street near you for some time. “We’ve had extended discussions with Transport for London for a long period of time. There is a plan for an elevated cycleway from Amsterdam to Schiphol Airport in Holland and they are going to see how that goes,” says Hodgson. “We think it is disappointing that London is not taking a lead in this.”

Unless Livingstone’s taste for innovative transport solutions comes to the fore in a hurry, it looks as though London’s battered cyclists will be casting envious glances towards the Continent for some time to come.

Paying with plastic: Why road engineers love polymer composites

Composite materials are being used increasingly for highway structures because they are maintenance-free. "The Highways Agency has really picked up on this," says David Kendall, director of Cetec, White Young Green's specialist structures division. "The initial cost may be more but it makes sense to pay it as these highways structures cost a lot to maintain."

There are other advantages, too. Composites are very light and large prefabricated sections can be easily craned into position. "Usually, an awful lot of the cost is in the installation and disruption," explains Kendall. "For example, with railways you might only be able to position structures in the middle of the night on a Sunday, so big sections are a major advantage."

Examples where composites are already used for highways include motorway gantries. Conventional 48 m long steel gantries weigh 130 tonnes, but a composite version weighs just 20 and is positioned in one piece.

The bridge at Mile End, where the first Scyway could begin, has fibre-reinforced plastic cladding. This is pleasantly curved and enables workers to walk inside the bridge to carry out inspections. Cetec is currently working on 20 m long FRP bridges capable of carrying dual carriageways. According to Kendall, FRP bridges are popular in the USA because they are resistant to corrosive road salt.

A range of materials can be used to reinforce the plastic resin in FRP. Glass fibre has been used for many years, and carbon fibre is becoming more common after a recent drop in price. Kendall says Scyway would probably be constructed using both. Other materials used for FRP include Aramid, which is also used for making bulletproof vests.

The plastic is formed using moulds, so it can be supplied in a wide variety of shapes. "The Scyway deck is likely to be a hollow box but quite curvaceous because we can mould curved shapes as easily as straight or faceted ones," says Kendall. He says the moulds for Scyway would be expensive but if they were used to make many miles of deck, an attractive economy of scale could be created.