Another red bus goes green for London

Take your photos now, London’s iconic red double-decker buses are going green. Luckily not literally. Transport for London (TfL), the government body responsible for transportation in Greater London, is investing heavily in reducing the environmental impact of its operations and encouraging Londoners to rely on sustainable methods of transport. Are their efforts sufficient to meet the Mayor’s target and reduce London’s carbon dioxide emission by 60% of their 1990 level by 2025 [1]?


Transport and climate change

Transport accounts for 14% of greenhouse gas emissions globally [2]. The World Bank recommends comprehensive approaches to reduce greenhouse gas emission from transport focusing on:

  • the reduction of demand by appropriately designing cities;
  • the use of most energy-efficient technology possible for all trips; and
  • the promotion of walking, cycling and public transport [3].

While TfL has limited influence on urban design, its investments combine the second two recommended approaches.


Investing in greener operations

TfL is attempting to use the most energy-efficient technology for as many of its trips as possible with significant investments both in its bus and underground networks.

The first diesel-electric hybrid bus was introduced in London in 2006. Since then, about a quarter of London’s bus fleet has been replaced by hybrid options. These hybrid buses reduce carbon dioxide emission by approximately 30% compared to conventional buses [4]. An even more efficient alternative is a hydrogen fuel cell powered bus, which only emits water. TfL is currently experimenting with a small fleet of eight single-decker versions of these. Broader adoption may be limited as the majority of London’s bus routes operate double-deckers. To drive a material reduction in carbon dioxide emission across the bus network, the transition to hybrid buses should be accelerated in the years leading up to 2025.

Green buses are a great start, but by no means sufficient in a city where roughly 40% percent of journeys are taken by the underground [5]. Last year, TfL introduced two new initiatives to reduce emissions in the tube network as well. Regenerative braking technology recycles energy from train brakes to power stations. A 2015 trial showed enough energy can be saved to operate even larger underground stations for two days per week – saving about 25% of electricity used at the station [6]. A separate initiative will revamp the Greenwich Power Station into a low carbon power generator for the underground network [7]. As opportunities to change the trains themselves on the underground network are limited due to physical constraints, TfL focuses on reducing the energy consumption of its underground stations. The widespread implementation of these initiatives could bring significant benefits in the long run.


Promoting sustainable transport choices

The second pillar of TfL’s strategy to reduce greenhouse gas emissions relies on encouraging Londoners to switch to sustainable transport options.

London introduced the biggest congestion charge theme in any major city in 2003, charging £5 then, £11.50 now daily for cars entering Central London between 7am and 6pm on weekdays. Though it faced resistance initially, traffic levels decreased by about 10% since the introduction of the congestion charge [8]. In fact, car ownership started to slowly decrease in the capital after 2003 [9].

In more recent years, the focus shifted to developing London’s bicycle routes. The East-West and North-South cycle superhighways are visibly busy with commuters during rush hours. These routes reserved for cyclists provide safer and faster options to cross the city. The latest statistics suggest a 5% increase in cycling journeys to about 23 million a year [10]. The constant roadworks improving the cycle road network have increased journey times in the city for those travelling by car. This may convince further travelers to take public transport – especially the underground – instead of driving.


Enough progress against the target?

The investments of TfL reduce the environmental impact of its operations and successfully encourage Londoners to rely on the public transport network. They have also sparked discussions about sustainability in the city. The biggest challenge ahead of TfL is scaling these green initiatives. Assuming the same conversion rate from conventional to hybrid buses, about half of London’s bus fleet will be low emission by 2025. This would translate to a 15% reduction in emission across the bus network only. Implementing the regenerative braking program for all underground stations will take years and will lead to a 25% emission reduction in total. Even if these initiatives were implemented much faster, TfL would need another set of innovative solutions to meet the 60% emission reduction target by 2025.


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[1] “Climate change and weather, Mayor of London,, accessed 3 Nov 2016

[2] Rebecca M. Henderson, Sophus A. Reinert, Polina Dekhtyar, Amram Migdal, “Climate Change in 2016: Implications for Business”, p 14, HBS Case N2-317-032

[3] “Urban Transport and Climate Change”, The World Bank, 14 Aug 2012,, accessed 3 Nov 2016

[4] “Hybrid bus boost for London”, Transport for London website, 9 Oct 2015,, accessed 3 Nov 2016

[5] “Transport for London Annual Report and Statement of Accounts 2015/16”,, accessed 3 Nov 2016

[6] Katie Sadler, “Recycled energy from Tube train brakes to power Underground stations”, Eurotransport Magazine, 25 Sep 2015,, accessed 3 Nov 2016

[7] “Low carbon plans announced for Greenwich power station”, BBC, 8 Jan 2015, , accessed 3 Nov 2016

[8] Claire Timms, “Has London’s congestion charge worked?”, BBC, 15 Feb 2013,, accessed 3 Nov 2016

[9] “Roads Taskforce – Technical Note 12: How many cars are there in London and who owns them?”, Transport for London,, accessed 3 Nov 2016

[10] “Number of cyclists in London reaches record high”, BBC, 4 Jun 2015,, accessed 3 Nov 2016


Photo credit:

“London’s iconic buses are going green”, Wired Magazine,, accessed 3 Nov 2016


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Student comments on Another red bus goes green for London

  1. I think TfL is doing a good job trying to get Londoners to go around in a more sustainable way, being it through greener buses, promoting cycling, or reducing energy consumption in the underground system. However, having lived in London, I cannot avoid remembering the chaotic traffic that I often encountered in the city center. Although the city has imposed charges on cars entering the city, I believe that is not enough. The new mayor Sadiq Khan is considering measures such as reducing, or even banning, traffic in some of the most polluted areas of the city, such as Oxford Street. However, perhaps more radical measures should be taken – Paris tried a “day without cars”, which resulted in a 30% reduction of NO2 levels in the Champs Elysées. I believe mayors of major European cities should consider trying more radical measures such as this one in order to try to control pollution levels and contribute to reducing the impact on climate change.

  2. Great article! I just question the economic effects of this all has on the City. I think it is great – but with the extension to Heathrow going/not going ahead, what exactly is going to happen to London being the financial hub of the world?

  3. Really enjoyed this post! Having lived in London for a year, I recall that the public transit was generally very reliable / efficient, but that there also were occasionally signal issues or similar that would disrupt the tube (especially the Northern Line, which once trapped me in an non-A/C car in a tunnel for 30 min on a 90 degree day…). I wonder, what impact do upgrades such as regenerative braking have on reliability? Similarly, I recall that certain public transit lines would become very crowded during peak hours, such as the Jubilee line. How will the city be able to balance growing use of public transit due to sustainability initiatives with capacity on those routes?

  4. Thanks for the post Agnes! I am especially interested in finding out about ways in which big cities are dealing with CO2 emissions and traffic issues. While living in Mexico City, I was constantly stuck in traffic and feeling sick because of the high levels of pollution. The city administration also launched a couple of initiatives that were helpful, such us “Hoy No Circula” that limited the number of cars that could circulate in a day. Best practices can be shared among these highly populated urban areas to solve these big issues.

  5. I think you rightly identify that one of the biggest challenges TfL will face will be to scale its green initiatives to meet the 60% emission reduction target by 2025. You seem to suggest that the progress made thus far – a 10% reduction in traffic, a 5% increase in cycling – provides a solid start but is not sufficient. With respect to cycling, in particular, do you know what TfL has done in order to encourage behavior change among commuters (aside from simply improving the cycle road network)?

    One question that comes to mind in thinking about London’s medium-term future is whether this 60% target will remain relevant and reachable in light of the city’s continued sprawl into Zones 4-6 (and potentially beyond)? If London’s population continues to grow and put pressure on existing infrastructure, it seems as though Joana’s suggestion of adopting more radical measures to reduce emissions may be necessary. Do you have any thoughts on what additional extreme measures might be? I’m thinking along the lines of Londoners having greater flexibility to work from home, but I’m also wondering how TfL would approach this and similar ideas. With whom would TfL have to partner to make changes that are well outside the scope of managing the tube, buses, and bicycle lanes?

  6. Thank you for the interesting article about London’s transportation. London’s efforts to put “greener” buses on the road remind me of the Transantiago project in Chile that transformed the public transit system. By replacing diesel buses with new non-diesel buses, emissions were noticeably reduced. However, a study showed that changing the bus types were not always sufficient in reducing emissions on certain streets. Reducing overall traffic had a more significant effect. ( London seems to have the right idea by tackling transportation emissions from multiple angles all at once.

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