Route Mastery :The Future of the London Bus (Part 1)


We are ashamed to admit that there is a distinct bias on London Reconnections towards trains. Despite the fact that it is used for 50% more passenger journeys than the Underground, the venerable London bus is infrequently mentioned. As we enter a period where bus technology is rapidly evolving though, it is time to look at where London’s buses are, technologically speaking, and were they are going. In part one we thus look at the New Bus for London – Boris’ “New Routemaster,” and more particularly at the vehicle behind the political hype. If it had a bonnet we would delve beneath it.

This article will look at the future of the London bus and by that we mean the bus itself. Whilst from the passenger perspective great changes have been seen in recent years, with more to come (not least the end of cash fares now confirmed to happen on the 6th July) the basics of how the bus itself has been powered has not changed that much. Typically it has an engine, two axles, usually two decks and runs on diesel fuel. The engine is connected to the wheels by a propshaft. Speed is determined by engine speed and a gearbox.

Buses beneath the Wires

Buses in London have become much more accessible and comfortable but these things tend to be of a more evolutionary nature. At the same time there are those who would argue that in some ways we actually had something better than today’s bus many years ago in the form of a trolleybus – fast, high capacity, no noisy internal combustion engine and, to use modern parlance, no tailpipe emissions. Those who are believers in trolleybuses remain disappointed that they are never given any consideration in modern transport thinking within London.

It is important, however, not to view these things from just one perspective. In contrast to the trolleybus evangelists there were those at the time who felt that the rather inflexible trolleybuses were quite rightly consigned to history and that the bus was the future. Instead, the golden days are nostalgically perceived to be the heyday of the Routemaster – the last bus specifically designed for London’s needs before the government required London Transport, as it then was, to buy off-the-peg buses in order to qualify for a substantial grant towards the cost of the buses.

Buying generic

The off-the-peg buses that came after the Routemaster were built in the north of England. The bus builders (especially the state run one) knew they had a captive market and then, as now, the choice of suppliers was skewed by political dogma. This is not to say that elected politicians should not be involved with specifying what buses London should have, but there is a world of difference between an elected London mayor taking into account additional factors that may not be of primary concern to TfL and a national government sacrificing then needs of London to prop up industries that cannot operate competitively due to the poor quality of their product.

trafalgar square

A busy New Routemaster at the eastern side of Trafalgar Square. Most of the passengers appear to be tourists. At times and locations like this there appears to be a clear benefit in having three doors and a conductor on the rear platform.

The current builders of London’s buses

Over time, the quality and suitability of buses for London has improved, with London Buses operating in a free market and two firms in particular being very responsive to the requirements of London Buses. In the old days London Transport officials would visit the production line at Park Royal to ensure that the Routemasters were built to their exacting specifications. In today’s world one doesn’t design the bus and tell the bus builder to build it, one explains what is required and works with the bus builder so that they can provide that.

front of lower deck

A front view of the lower deck of a New Routemaster. Looking at this one would be justified in wondering what the fuss was about. This is very similar to any double decker bus now running in London.

One of London’s bus builders, Alexander Dennis Ltd (ADL), actually assembles their buses in Guildford. With a worldwide market but London at their doorstep they have shown consistent willingness to adapt their designs to the London market and this may in part account for the fact that they currently have around 47% of it. They see themselves as evolutionary bus builders with a world-wide reputation that needs to be maintained. They are also aware that to ensure competition they are unlikely to get more than 50% of the London bus market regardless of how good a bus they produce.

rear of lower deck

A rear view of the lower deck of the New Routemaster built by Wrightbus. This is on route 24 south of Victoria which is a very quiet part of an otherwise busy route. The floor is low throughout which means that the seats over the wheel arches are exceptionally high and that some have to be rear facing. Like the previous picture there does not seem to be anywhere to house certain vital pieces of equipment – such as an engine.

Wrightbus, based in Northern Ireland, currently holds the number two spot within the capital, which makes it very aware of the “must try harder” requirement. Unusually it is privately owned, which means the firm isn’t nervously looking over its shoulder at shareholders who might be concerned as to whether their strategy is the most profitable one. On the world stage it is not so established as ADL so is probably more dependant on the London market. At the same time Wrightbus does not have the might of the resources that ADL has behind it. It does, however, have a good working relationship with both TfL and Arriva who, amongst many other things, run some of the buses in London. Wrightbus’s Gemini double decker is similar in appearance to ADL’s Enviro 400 series of buses and comes in both conventional and hybrid versions which are both found in London. It is a Wrightbus body built on a Volvo chassis – which harks back to Wrightbus’s roots as a bodybuilder.


Because the engine can go anywhere is has been conveniently placed under the rear staircase thus utilising space that would otherwise be wasted.

cropped fuel inlet

The cover of the fuel filler cap. Cunningly hidden flush with the rest of the bus this shows the attention to design detail. The filler cap is here because the fuel tank is underneath the front stairs

Beyond these two suppliers, there are other bus builders that have a presence in London. A notable third is Volvo, but because of their size they tend to offer a product with standard variations and it is generally a case of “take it or leave it.” Mercedes also have a presence but a lot of their fleet went with the disappearance of bendy buses. Again, being a very large player in a world market it is more a case of Mercedes offering a standard product with various options and service providers then seeing if these buses are consistent with TfL’s specified requirements.


Upstairs on a New Routemaster at night. The design is distinctly retro and loved and hated in equal measure it seems. Photo courtesy Graham Feakins.

Air Quality

Having set the supplier scene, we now move on to a seemingly unrelated subject but one that is in fact very closely bound up with the future of the bus in central London – air quality.

TfL has a large and varied range of responsibilities. It seems to have acquired or have some responsibility for various peripheral activities in its short existence such as licencing roadworks, licencing buskers, crime prevention, anti-terrorism, operating a cable car over the Thames and cycle proficiency.

A responsibility that one would probably not associate with TfL is air quality, yet some would argue this is amongst one of its most important responsibilities that it has. It is certainly one that is of great concern to the Mayor. Whether this is a result of the threat of large EU fines or a realisation of how diesel particles are a silent killer that affects the health of Londoners is something on which we leave readers to form their own opinion. It is certainly not the case that London is alone as was recently shown during a period of smog in Paris when driving was restricted and public transport made free in an effort to reduce it.

What is often the case though with the EU is that it not just the issue of the breach of regulations that matters, but what the offender is doing to rectify the situation. So, apart from any health benefits to London or political benefits to the the Mayor, he has a strong incentive to be seen to be taking the problem seriously and have a programme in place to address this issue.

Targeting the culprits

The problem is, as ever, that politicians don’t want to do to much to upset voters and businesses. So when it comes to pollution from transport and those particularly troublesome diesel particulates the first stage is for TfL to put its own house in order. This is no bad thing, for this, combined with further tightening of the requirements of commercial vehicles from 2020, means the biggest problem in central London will actually be from buses and taxis – both of which are under TfL’s control.

Taxis leading the way

In a radical but very little noticed move, TfL has actually announced that new taxis will be required to be zero emissions capable from 2018.

The Mayor of London, Boris Johnson, today (Thursday 16 January [2014]) announced plans that would require all new taxis presented for licensing in the capital to be zero emission capable from 1 January 2018, with the expectation that they will automatically operate in zero emission mode while in areas where the capital’s air quality is at its worst such as parts of central London.

It is clear from the press release that the objective is not so much an improvement of overall air quality but an aggressive targeting of hotspots. In reality this is likely to be within a few hundred metres of the air quality recording stations with the highest readings. At the same time, even using today’s more conventional hybrid technology, this should lead to reduced emissions of at least 30% and be cost effective over the life of a taxi – though obviously it will require more capital investment upfront.

It will interesting to see how the zero emission taxi will be implemented and enforced. In particular whether there will be GPS or similar to define the areas. It does seem that it will be a requirement that the the engine would automatically switch over if not already in electric mode. It is not stated whether the areas affected would be static or dynamic. One would expect that a similar technology could also apply to buses and both ADL and Wrightbus have stated that it would not be hard to make their hybrid buses zero emissions capable to enable them to run for a mile or two without any tailpipe emissions at all.

Other vehicles are not forgotten in the press release which goes on to state:

The news follows a pledge the Mayor made last year to introduce an Ultra Low Emission Zone in central London by 2020.

Cleaning up the buses

When Boris Johnson became mayor London already had hybrid buses. These were basically existing bus designs that were “hybridised” by adding regenerative braking, a lithium-ion battery and, in parallel with the existing mechanical transmission, a means of powering the wheels electrically. The source of the electrical power was from regenerative braking.

The early hybrid vehicles were not entirely satisfactory for a number of reasons. The first and probably main one was simply cost. For the 20-30% saving in fuel (and emissions) you had an awful lot of extra initial cost in buying the bus. It is said that the hope was that by TfL buying a lot of hybrid buses a new demand would be created that would result in economies of scale and a reduction in the price. The trouble was that these price reductions just did not seem to be materialising.

Another major problem with these early hybrids is that they really did not reduce emissions by the level required. They were described as a “Prius-type” bus and in one sense that is really what they were. Just as the car manufacturers took an existing car and modified it, the bus manufactures did the same. By doing so they were not taking full advantage of the technology and either having to compromise on battery size or rather awkwardly include it in an existing design.

Series Hybrid v Parallel Hybrid

There appeared to be a real reluctance amongst bus builders to totally put their faith in hybrid buses and commit to it. This is rather like a Deutsche Bahn signal engineer who doesn’t really trust modern ERTMS signalling to do the full job and so sticks in a tried and tested signalling system in parallel. The earlier parallel hybrid buses weren’t fully exploiting the technology and they still had propshafts and gearboxes which were really completely unnecessary. ADL were already going along the route of progressing to so-called series hybrid where batteries power the bus and either a diesel generator or regenerative braking tops up the batteries. This they incorporated into their existing bus design – the Enviro 400.

A big advantage of series hybrid was that you didn’t need a propshaft and if you didn’t have a propshaft you could be quite radical and you could put the engine anywhere you wanted on the bus – upstairs if you wanted to. However, this was only really possible if you redesigned the whole bus. A complete redesign also gave the benefit that one should not be struggling to find space to include the sufficiently large battery required to store the energy recovered by regenerative braking.

One further advantage of the series hybrid was that, if the engine wasn’t turning the propshaft and all that it was doing was running an alternator to keep the battery topped up the engine could be much smaller. In fact the ADL EnviroH (H for hybrid) and the New Routemaster use the same small 4.5 litre engine. Potentially, if designed properly, one could always be running this engine at optimum efficiency and regardless of traffic conditions.

The Boris Bus

One can only speculate what thoughts were going on inside the heads of TfL directors when Boris Johnson was elected mayor of London, with his stated commitment of creating a new iconic bus for London with a rear open platform and a conductor on board. Shortly after his electoral victory he triumphantly appeared with Sir Peter Hendy and began talking about his new bus. Hendy had a microphone thrust in front of him and was asked what he thought. Clearly put on the spot, he replied to the effect that they could make something of this.

With many already used to Boris’s hyperbole his commitment for this bus “to run on green fuel” and be energy-efficient could not really assessed. Was it just a soundbite or something more serious?

The thought must have already been crossing some minds in TfL that if you are going to design a new bus that is iconic, and has to have green credentials, then this could potentially be a massive opportunity to innovate. It may have crossed their minds that if it all went wrong it might be the Mayor, and not TfL, that would get the blame. It certainly soon became clear that Hendy, whilst being scrupulously obedient to his political masters, had a somewhat radical agenda.

What we should aim to create now is not just a Routemaster replacement but a whole new generation of London buses that could affect the future of the entire industry.

In the competition to design and build a new Routemaster most of the contestants dropped out when they grasped the enormity of what was asked. Not surprisingly, given the scene we set earlier as to the current London marketplace, it came down to ADL and Wrightbus.

In many ways the situation was probably similar to procurement of Thameslink stock, with one home-grown supplier expected to get the contract and an unfavoured overseas one having to do that bit more to get the order. In the end it seems that ADL did not want to stick their neck out too far, especially as the company had recently been through some difficult times financially, whilst Wrightbus seemed up for the challenge. ADL wanted to build on their hybrid models that either already existed or were being developed whilst Wrightbus, despite their comparative inexperience at chassis building, wanted to embark on a radical design more in keeping with the mayor’s aspirations. Just how radical is probably best illustrated by the fact that at the time there were no purpose-built series hybrid buses in existence.

The rest, as they say, is history. The New Routemasters are offering energy savings of around 40% which means emissions reductions of around that magnitude. The all important NOₓ is around a half that of conventional double-deckers and even most hybrids. The CO₂ level comfortably beats other hybrids and is less than half that of a conventional bus.

There are obviously other opportunities for the future depending on how technology advances. For example, it is not currently possible to top up the charge in the New Routemaster’s batteries in the garage. As lighter materials get cheaper, it may also become more cost effective over the lifetime of a bus to replace some parts simply to reduce the weight further. A basic bus designer’s maxim is that “weight means fuel”. During the lifetime of any bus one would expect the engine to be replaced at least once. One would also expect on a bus like this to replace the lithium-ion batteries once every five to seven years. These occasions may also be an opportunity to take advantages of further advances in relevant technologies.

If one wanted to be even more radical (and playing something of a devil’s advocate), one could even, in principle, simply replace the diesel generator (engine + alternator) in a New Routemaster with a voltage regulator and connect it to a couple of trolley poles on the roof. One then has trolleybus – one with the added advantage of being able to run off wire for a short distance by using its battery. Of course you could do the same with a parallel hybrid, but from a technical standpoint it would a far less satisfactory solution. We will see in part 2 why this would probably not be good idea unless one already had the trolleybus infrastructure for it to run on.

There are lots of clips on YouTube about the New Routemaster. This rather old one from The Mayor’s Office, amongst other things, includes David Brown, MD of Surface Transport at TfL, explaining with passion what they wanted from the bus.

Navigating the Controversy

The New Routemaster has certainly been controversial. A lot of that has been down to looks with, inevitably, some loving it and some hating it. It has also been seen as Boris’s vanity project – but that should not be seen as a reflection on the bus itself – just the process by which it came into being. Likewise, the issue of conductors seems to raise emotions, but again is a separate issue from that of the technology and engineering. Indeed it is probably fair to say that any pretence of these buses being frequently double-manned has effectively been abandoned now that they run on route 148 without any conductors at all.

There have also been other, more physical, flaws. The air-conditioning did not work in the early days, for example (but then the original Routemaster has some major design faults in the early days as well). There have also been criticisms over its weight. As the design has developed the unladen weight has gone down, but this has lead to the strange situation of different but identical-looking buses being authorised to carry different numbers of standing passengers.

doors closed

A New Routemaster in central London in the afternoon on route 148. The rear door is closed and there is no second crew member. This shows that the bus does not require a crew of two to operate it at any time and whether or not it has a conductor is ultimately the choice of the current mayor.

All the above criticisms will no doubt be forgotten about in time by most people, leaving only those with a long memory and those who are determined to condemn the New Routemaster on past faults. Unlike the original Routemaster though, the New Routemaster will probably not be on our streets for more than around 15 years. The modern economics of buses including re-certification means it doesn’t usually make sense to keep buses going for longer.

Even if the New Routemaster survives for more than the expected 15 years (availability of spare parts is guaranteed for 29) they will probably be relegated to a less demanding location. More critically the bus is going through a phase where development is changing rapidly and, although the New Routemaster is unlikely to replicate the original’s longevity, it will almost certainly be seen as the first of a generation of buses that broke the traditional mould.

Indeed back in 2010 we asked whether the obsession with rear-entry by media and mayor meant that the real legacy of the Routemaster was being lost. We asked whether an opportunity was being missed to take a leap forward in bus-building, both in terms of the way they are built and their environmental friendliness. Whilst the New Routemaster cannot be said to have entirely embraced both those opportunities, we must admit that – politics ignored – it has done so more than any of us here in LR towers anticipated. It is a “B+, good effort” when we were perhaps pessimistically expecting a “D.”

If the mould has now been broken though, then what then comes next? In our next article on this subject we will look at other alternative technologies. These technologies may mean that the New Routemaster will not be seen as futuristic or iconic for long, but if that’s the case then it will be, at least in part, because the New Routemaster opened the door for them…

…even if it was only the front door that it opened. Not the rear one.

Much of the information for this article was taken from “Boris’s Bus” published by Capital Transport. Until recently it was almost impossible to buy at a discount and it is quite expensive at nearly £20. The London Transport Museum does not stock it and this is allegedly because they refuse to sell it. This is somewhat strange to say the least. Whilst the book is definitely a “warts and all” offering it does tell the story of the bus in great detail and the overall picture is one of being very impressed with what was achieved. Thanks also to ngh for clarifying a number of technical matters.

Written by Pedantic of Purley