• Phone
  • Contact us
  • Locations
  • Search
  • Menu


  • Add this article to your LinkedIn page
  • Add this article to your Twitter feed
  • Email this article
View or print a PDF of this page

Can total car emissions be reduced enough by 2020?

Phil Jeanes
Traffic Engineering & Control
January 2010

Cars are a big problem for the Government’s Carbon Reduction Strategy for Transport which was published last July. This proposes a process of carbon budgets to address global climate change and achieve a projected reduction of carbon emissions of 34% by 2020 and 80% by 2050. Transport has the second largest budget, with 17% of all UK emissions. Of the total transport carbon emissions, 58.3% are from cars, making the reduction of car emissions one of the most challenging targets. So is such a reduction feasible?

To reduce emissions to the level required by the Carbon Reduction Strategy there are a number of approaches that can be considered:
• Increase the fuel efficiency of cars so that fewer emissionsare generated, either by better petrol and diesel engines or using hybrid and electric vehicles
• Reduce the extent of car travel, for which three methods could be applied:
• Reducing the desire to travel – through encouraging home-working and shopping, or making it more expensive
• Using other modes of transport – depending on the quality and flexibility of public services and the active alternatives
• Improving the efficiency of the road transport system by putting the premium on car and vehicle occupancy. 

Increasing the fuel efficiency of cars is not enough for 2020
Although there will be some significant gains from more efficient traditional, hybrid and electric cars, in the short term, this will not be enough. It is the cars we all drive today that produce short-term emissions, not the cars bought tomorrow. The EU’s (and DfT’s) target of reducing 2020 from 158 today) will have little effect until the number of more efficient vehicles becomes a significant part of the overall car population. However, PA’s view is that the average emissions from new vehicles in Europe will be up to 35% higher than suggested by the EU target in 2020 at around 130 rather than 95 gm/km.

Currently, hybrid and electric vehicles are a tiny proportion of sales and the current DfT projection is for around 800,000 electric or hybrid cars to be sold by 2020, barely 2.5% of the car population. This means that most new vehicles purchased will be petrol or diesel powered, albeit producing less carbon dioxide on average than current vehicles. The number of such new cars bought will also depend on how buoyant the economy is in the interim; many new, more efficient cars will bring down the total emissions, but only marginally. We are reliant on consumers responding to climate concerns by buying smaller more efficient vehicles.

Even if we make the optimistic assumptions that new car fuel efficiency will fall 39% (as the EU targets require) and electric vehicles are popular and do form 5% of the vehicle population by 2020, we still need overall demand to fall by 15.3% to meet the target of reducing emissions by 34% by 2020. There is no escaping the fact that we will all need to drive a lot less, so that the average mileage travelled by each car reduces by about 1,800 miles a year. That equates to 36 miles a week, far above the Government’s recent ‘Act on CO₂’ request to reduce by five miles per week. Furthermore, as fuel economy improves, the apparent cost of travel falls and it is likely that many will choose the convenience our own private transport over public transport that has been the dominant travel choice for decades.

What can be done to reduce the amount we drive our cars?

In economics the approach to restricting demand is through pricing mechanisms. Although the concept of adjusting travel demand through pricing is practised on the railways and buses through subsidised fares and services, it is not felt appropriate to apply the same mechanisms to the roads. Various forms of road pricing have been considered but are politically unacceptable in the UK. However, this is not so in Holland. The Dutch are pushing ahead to introduce an advanced road pricing programme that aims to reduce road travel demand by 15% overall by encouraging more efficient use of the road network and reducing overall emissions by 25% over the period to 2018. This is to be done by shifting the tax burden from sales taxes, which are high in the Netherlands,to road usage charges at a level building up to €0.05 per km (approximately £0.075 per mile) for private cars, much more for HGVs.Investing in pubic transport and encouraging ‘smarterchoices’ (the DfT’s policy to encourage use of low emission modes, in particular walking and cycling) will have an impact where there is sufficient public transport to provide a viable alternative, such as in metropolitan areas.

However,most car travel is in areas poorly served by public transport and without the density of journeys needed to support economic services. Demand Responsive Transport (DRT) (typically Dial-a-ride schemes) provides an option in such areas but is usually a subsidised, specialised service for those unable to drive, rather than a means of replacing car travel. The table above shows the difference between travel by mode in different environments showing how dependent most people are on their cars.

Encouraging other modes through ‘smarter choices’ is hoped to reduce car demand by up to 3%, and this is possible in areas where active modes (cycling and walking) are realistic for short journeys (which produce proportionately more emissions per km due to cold starting etc). Longer journeys, typically city to city, are also responsive to public transport enhancements, such as rail and bus service improvements. However, this leaves the major proportion of car travel with no effective alternative.

Improving car occupancy is essential for an efficient, sustainable transport system
Even if we can encourage large numbers of people to reduce their car usage through ‘Act on CO₂’ and ‘smarter choices’, this will still not be enough. Road travel itself needs to be more efficient. Most cars travel with only one or two people in a car, an average of 1.58 passengers per car dropping to under 1.2 per vehicle for travelling to work. To put it another way, only an estimated 25% of emissions are caused by people travelling, the rest are created to move empty seats from one place to another.

One method of improving car occupancy that is widely considered is car-sharing. This is used mainly for workplace commuting through internet web sites and has perhaps 400,000 members currently in the UK. These schemes are encouraged by policies at both local level and nationally by the DfT. Thus far, increasing car occupancy through car-sharing has generally had slow takeup due to a number of reasons:
• the lack of trust in unknown passengers, unless they are work colleagues or friends
• the inflexibility of the methods of matching those wishing to share, resulting in the rigidity of prearranged lifts etc
• concern to ensure the return journey is fully covered by the chosen lift(s)
• the lack of real incentives to do so beyond the saving of costs.

Enhancing car-sharing to be more flexible and adaptable to address these issues is an idea that’s already been looked at in Europe – pilots are operating in Madrid and the Netherlands – as well as the USA, where car-sharing and car-pooling organisations have been established in many states. The car-sharing concept was not originally focused on the emissions benefit, but more on the occupants’ savings on fuel and parking charges which can then be shared between all those involved. However,today the emphasis is shifting to include the ‘feel good factor’ of reduced emissions and doing the right thing and taking personal responsibility for emissions.

So how can we develop greater levels of car occupancy?
To increase car occupancy, today’s social networking technology can provide rapid and trusted matching both for those looking for a ride and those looking for passengers. Social networking technology, by using ‘affinity groups’ – groups that both the rider and driver have chosen and trust – and knowing location and destination is thus able to identify potential rides on an as-needed basis that will transform car-sharing. In addition, accessing and presenting real-time information about local public transport options would enable the traveller to make optimum decisions about how to travel to their destination.

In this way ride sharing can also help improve the usage of public transport since everyone would have their own ‘Journey Adviser’ giving information on local rides, buses and trains. This would help strengthen existing public transport networks and reduce emissions whilst giving greater freedom of choice to the individual. This means that a stronger link can be established between private travel and public transport, at least for those willing and able to engage with the technology.

In areas where there is extensive public transport, for example, London or Manchester, the emphasis should be on encouraging greater connectivity and ease of switching to public transport, achieving modal shift. In suburban and rural areas the introduction of a community of ride-sharers would bridge the large gap between the convenience of travelling in one’s own car or using sparse public transport services. Essential for all such decisions is having information to hand and a consistent means to pay for whatever choice one makes.

Recording individual’s decisions not to drive will give personal responsibility which can be rewarded through incentives such as carbon accounts. Riding rather than driving saves carbon emissions which can be recorded for each user. The accumulated savings may then provide a carbon offset which may help to meet businesses’ short-term carbon reduction commitments. Other methods of significantly reducing carbon emissions, for example, by building new rail capacity, are all long term and require significant investment in new infrastructure. Carbon accounts would extend the benefits of ride sharing beyond regular commuters to the millions of drivers who make ad-hoc journeys and maximise access to public transport, too. It's all do-able, it just needs the political will.

With carbon accounts could come a carbon tax – which would stimulate new economic activity as people seek to minimise their exposure to the tax. For example, an updated version of the car scrappage scheme could stimulate
demand for electric vehicles, with the investment needed for infrastructure contributing to economic activity growth. This would provide greater environmental benefits by giving a clearer message than just increasing Vehicle
Excise Duty (VED) even if the emission bands became more differentiated. A piecemeal approach of policy initiatives cannot generate sufficient critical mass for success without a range of incentives and encouragements for behavioural change.

Individual actions within a policy, such as new car sharing schemes or business travel planning, are important ‘bottom-up’ means of encouraging a move away from car travel, and hence emissions. However they will not introduce a sufficient shift to meet the level of reductions needed. What is needed is a focussed package of measures that seeks to establish a critical mass of drivers, around 20-25% of all drivers in a local area, who are available to meet the needs of riders within that area. Only through a concerted and incentivised programme would we be able to significantly increase car occupancy and provide the UK with a panacea for reducing the emissions of our road transport system – the lone driver.

The key components that would enable this to succeed and act as a model for other areas are:
• an area with high traffic volumes, in particular daily commuter flows, and the attendant low levels of car occupancy
• relatively little public transport (eg rail or trams) able to meet the need because of the diversity of trip destinations
• Relative affluence, environmental concern, social responsibility and acceptance of technology.
• Large enough scale to establish a critical mass but small enough to be economically addressed as a large scale pilot project.

There are a number of areas where these criteria would be met – and each one has a record of considering innovative approaches to their transport problems:
• Cambridge and Reading, where there are constraints from the existing infrastructure,
• any of the new EcoTowns, which are green field sites are traditionally designed around car travel, especially regarding employment
• within a Sustainable City where there are existing large investments in public transport services to be integrated and a manageable scale established in the first instance.

In all of these areas there is the opportunity to investigate new ways of reducing emissions and improving transport efficiency using central funding. The Transport Innovation Fund was set up for such a purpose. To do this there are three key requirements to meet the challenge of Low Carbon Transport and achieve sustained reduction by increasing car occupancy in the medium term:
• Use of today’s mobile technology to provide real time access for a secure and flexible means of matching passengers to cars – and this technology already exists
• Active participation and integration with public transport and its travel information to optimise personal decisions and encourage reduced emission transport modes – transport authorities need funding to do more of this
• A programme of incentives to encourage and deliver long-term changes in behaviour and establish the critical mass needed to provide riders with a credible alternative to their own car
• A full scale pilot can set the parameters and investigate the extent to which real behaviours would change in response to the substantial public concerns of climate change.


Meeting the challenge of a sustainable and efficient transport system Although there are many good intentions in the Carbon Reduction Strategy for Transport, we need more serious steps to increase car occupancy in the short term otherwise the Government’s targets will not be achieved. Improving vehicle technology and fuel efficiency does not provide sufficient reduction across the whole vehicle fleet. In the medium term, modal shift requires significant investment to extend public transport serving the majority of trips in urban areas, but not in suburban and rural areas where most car travel occurs. Simply increasing the cost of driving would be unpopular with everone is like to damage the economy.

It is only by increasing car occupancy through today’s mobile social networking technology and effective incentives to gain full public support, that we will discourage the one-person-one-car culture that is threatening to forever change our climate. Perhaps the greatest incentive for many people to do this would be to realise that the only alternative to increased car occupancy is to follow the Dutch approach and raise the cost of road use.

Phil Jeanes is a transport specialist at PA Consulting Group. He can be contacted by email at phil.jeanes@paconsulting.com. For more information visit http://www.paconsulting.com/industries/transportand-logistics/



Sign-up to receive company updates and press releases by email or newsfeed:



Corporate headquarters
123 Buckingham Palace Road
London SW1W 9SR London SW1W 9SR
United Kingdom
Tel: +44 20 7333 5865 Tel: +44 20 7333 5865
contact us now

By using this website, you accept the use of cookies. For more information on how to manage cookies, please read our privacy policy.