Bus of the future: NB4L's green credentials

30 August 2012

The early part of 2012 saw the unveiling of the New Bus for London (NB4L), a project that has attracted admiration and opprobrium in equal measure. Rod James speaks to Mike Weston of Transport for London about the NB4L’s green credentials, the problem of fare evasion and how hydrogen-cell technology could revolutionise urban bus transport.

It's a sweltering summer's day in London and you are a passenger on the number 38 bus. At Piccadilly Circus you encounter gridlock, a dense clump of traffic that shows no sign of dissolving. As time drags on, your fellow passengers start to get agitated. Late for a meeting, an office worker presses incessantly on the bell, urging the driver to open the door. Another follows suit, followed by another and another. But as the driver has yet to reach the designated stop, his passengers will just have to wait.

For anyone who lives in London and travels regularly by bus, this is a familiar tale. The narrow, congested streets mix uneasily with box-like double-deckers and the recently decommissioned bendy buses. Not since the Routemaster, which ceased service in 2005, has a bus been designed with the specific needs of the city in mind. That changed in February this year, with the introduction of eight New Bus for London (NB4L) vehicles.

Past becomes future

Heavily modelled on the Routemaster, the NB4L is very much the pet project of Mayor Boris Johnson. Like its predecessor, it has an open platform at the rear, which allows passengers to jump on and off inbetween stops, improving the circulation of passenger traffic. It is also manned by both a driver and a conductor, a return to the old - and some might say halcyon - days. But London Buses director of operations Mike Weston insists that this is not just an attempt to replicate the past.

"This was an opportunity to start from a clean sheet of paper and design something specifically for our needs," he says in a side room at Transport for London (TFL)'s huge, open-plan headquarters in Southwark. "There are currently eight prototypes and they'll run on the 38 route [from Clapton Pond to Victoria] until around March 2013, when we should have enough production vehicles to convert the first route completely."

The Routemaster became a design icon, but was initially conceived purely with functionality in mind. NB4L wears its aesthetic credentials on its sleeve. The bus is defined by its rear curved-ribbon window and two art-deco-inspired staircases. It was designed by Thomas Heatherwick, creator of the London 2012 Olympic cauldron. According to Weston, after an initial period of uncertainty, users are coming back around to this way of travelling.

"In the long run, I think it will change passenger behaviour and we’ll find the bus being used in the most efficient way, with the two staircases making boarding and alighting much smoother."

"For the first couple of days, people weren't quite sure what the platform was about," Weston says. "But slowly people are beginning to understand how it works. In the long run, I think it will change passenger behaviour and we'll find the bus being used in the most efficient way, with the two staircases making boarding and alighting much smoother."

Under the chassis

Passenger behaviour is a salient issue. On the bendy buses, passengers could board through any door and tap their travel card (known as an Oyster card) on one of a number of pads. Not having to pay in view of the driver led to a dramatic increase in fare evasion, to the point where the vehicles became informally known as 'free buses'. The return of the conductor will help to remedy this, although Weston believes the problem of fare evasion needs to be viewed with a different perspective.

"Fare evasion on the bendy buses was higher, but there was also a perception factor," he says. "You didn't have to touch your Oyster card unless it was prepaid (pay-as-you-go). A lot of people assumed that others didn't have tickets, which led to copycat behaviour, even though the majority of them did. It's worth putting this issue into context."

Less well publicised, but more significant developments have taken place under the chassis. The NB4L is 40% more fuel-efficient than a conventional diesel bus and 15% more fuel-efficient than the diesel-hybrid buses already in operation on the network. It is configured as a series hybrid, giving it an edge over other hybrid buses in which the engine is running all the time, constantly generating energy for the battery.

"At the start of the project, London was already leading the way in Europe with the introduction of hybrid buses," Weston explains. "So it would have been unambitious to build something that wasn't greener than what we already have. The engine in the back is just charging the battery. But as long as the battery has a certain level of charge, the engine will cut out and it will run purely on battery until it comes down to a lower stated point of charge. In testing, we've seen that the bus is in battery-only mode for about 40% of the time, bringing emissions and noise benefits."

The technical design and manufacture of the vehicle was carried out by Northern Ireland's Wrightbus. The company amalgamated the most suitable technologies; the hybrid system came from Siemens and the engine from Cummings. Originally, six companies were invited to bid for the contract, a system adopted by TFL four years ago.

"Where we certainly led the way was in trialling multiple manufacturers and benchmarking them against each other," says Weston. "Some European cities had hybrids in small numbers from a single manufacturer. But in 2006 we looked at six different hybrid configurations from four manufacturers - probably the biggest single test of hybrid technology. The buses are the largest fleet under the mayor's direct control, so it is seen by many as leading by example."

Air quality strategy

The NB4L should be viewed as part of a wider green initiative that began in the mid-2000s. As London's population has grown, managing air pollution levels has proved tricky. A congestion charge was introduced in 2003 and TFL formulated an air quality strategy that saw buses fitted with exhaust filters and cleaner engines. These measures go hand-in-hand with efforts to encourage behavioural change.

"In the mayor's transport and air quality plan, there is a goal of reducing London's CO2 emissions by 60% by 2025," Weston says. "That is quite an ambitious target, but a lot of good things are going on around things like electric car charging points. We are also trying to encourage modal shifts, from cars to public transport, and public transport to bikes and walking."

Over the next few years, hybrid diesel engines will become standard for urban buses. In Europe, a number of trials are already underway involving electric buses, some of which entail the use of contactless induction charges.

"Not having to pay in view of the driver led to a dramatic increase in fare evasion, to the point where the vehicles became informally known as ‘free buses’."

"The bus of the future will be electric," Weston explains. "The only question will be how the battery is charged - through onboard generation or externally. We are paying close attention to trials in Europe that use induction charges, which allow you to put power into the battery remotely through infrastructure on the street. As things stand, having to plug the bus in for three or four hours a day isn't practical on a busy urban route."

Bus of the future

Looking even further ahead, hydrogen-cell technology is beginning to look less like a pipedream. TFL is involved in an ongoing trial of these vehicles in which energy produced from hydrogen fuel cells goes into a storage system, producing only water as an emission.

"We first tried it in 2003 through to 2007 with three buses and this is the second generation," Weston explains. "It's amazing technology, if still very expensive - the buses we currently have cost about £1m each. It is first-generation technology, so the price will come down. But big motor manufacturers such as Mercedes and Hyundai are putting a lot of money into fuel-cell cars, so issues to do with economies of scale are being remedied."

Some commentators have been quick to note the expense of introducing these buses at a time of public sector austerity. There are also somewhat justified claims that looking to the Routemaster for inspiration is a regressive step. Mayor Boris Johnson refutes these assertions.

"The NB4L is a shining example of what can be done with fresh, innovative thinking," he told Urban Transport Agenda. "My investment plan for transport will expand the NB4L across London with 600 new vehicles operating on the streets by the end of my second term. I will do this in a cost-effective way, by replacing existing buses as they are decommissioned. I will also ensure that each NB4L does not cost more to put on the streets than an existing hybrid bus."

We can't say at this point whether the mayor's words ring true. But a greener, UK-designed-and-built bus can only be a positive thing in the long run.

The new NB4L features a rear curved-ribbon window and two art-deco-inspired staircases, and was designed by Thomas Heatherwick, who was responsible for the London 2012 Olympic cauldron.
Mike Weston is operations director for London Buses.
Routemaster buses were more than 2m shorter and held 23 fewer passengers than the NB4L.
Eight prototypes of the new fuel-efficient NB4L will run on the 38 route from Clapton Pond to Victoria until March 2013 and the new buses be manned by both a driver and a conductor.

Privacy Policy
We have updated our privacy policy. In the latest update it explains what cookies are and how we use them on our site. To learn more about cookies and their benefits, please view our privacy policy. Please be aware that parts of this site will not function correctly if you disable cookies. By continuing to use this site, you consent to our use of cookies in accordance with our privacy policy unless you have disabled them.