Reducing the need to travel in the first place is the ultimate goal for achieving a sustainable transport future. Until that happens, tackling the problems of air and noise pollution and cutting vehicle volume is the best strategy for local government. Nick Warburton opens the debate on sustainable transport.

There can be little doubt that transport issues lie at the heart of the environmental health agenda. All forms of motorised transport create negative environmental impacts at every stage of production, use and disposal, in addition to having a profound influence on society's health and wellbeing. Transport planning and policy is therefore fundamental to public health, from the reduction of air and noise pollution to the promotion of development patterns to reduce the need to travel in the first place - the logical terminus to the whole transport debate.

The last decade has seen a global trend towards increased car ownership and usage, with serious implications for the environment, people's health and the safety of both car and non-car users. Strong incentives for driving, primarily convenience and independence, linked with self-expression and perceived social standing have all been contributory factors. At the same time, healthier modes of transport, such as walking and cycling, which many commentators claim are the most sustainable forms of travel, have not been widely developed to a level where the health impacts can be fully appreciated.1

In the UK, tackling vehicle-generated pollution is one of the central themes of the Government's transport strategy. Three years ago, its white paper on transport A new deal for transport: better for everyone, emphasised the need for local governments to integrate a range of issues covering land use, health, environment, education and transport. The public health costs of vehicle-generated pollution have been widely documented. In a report produced last year by the London Health Commission for the Greater London Authority, entitled On the move, it was revealed that more people die in the Capital from vehicle pollutants than from road accidents. While a second study, published earlier this year, revealed that poor air quality is more likely to affect people's health in smaller rather than larger cities, pointing to the examples of Liverpool and Swansea, which have, in relative terms, higher deaths rates per 100,000 than London and Birmingham.

As a consequence, the development of integrated and sustainable transport systems is vital in reducing the damage currently being done to the local and global environment and the health of society at large. According to Dr Jane Cloke (this issue, page 175), one of the main challenges for local authorities is to assess the extent to which traffic management policies can bring improvements in air quality as part of their action plans, the success of which rests on the employment of a wide range of strategies.

This is a viewpoint endorsed by Sean Beevers, a member of the Environmental Research Group (ERG) at King's College, London, which co-ordinates the London Air Quality Network (LAQN) with London local authorities. Last year, Mr Beevers warned environmental health officers not to depend on any one method to reduce air pollution, saying: "There is not a pro rata reduction in NO2 and PM10 concentrations brought about by reducing emissions from traffic".

Similarly, hopes for a sustainable transport system should not be pinned solely on the reduction of pollution levels by just cleaning up, or "greening", vehicles as a lone measure. The introduction of greener cars such as liquid petroleum gas (LPG) vehicles and the potential of fuel cells to produce quiet and emission-free transport will not solve the volume of vehicles clogging the national networks nor reduce their capacity to kill. Deike Peters, director of environmental programmes at the Institute for Transportation and Development Policy (ITDP) argues that other issues like reducing noise should also be taken into consideration.2 "There is little doubt that continued exposure to constant vibration and high noise levels (over 55 to 65 A decibels) results in sleep disruptions, anxiety, depression and stress, in turn negatively affecting people's economic performance", she says.

According to Dr Stephen Potter, senior research fellow at the Open University and director of its Centre for Technology Strategy, car journeys in Britain are set to rise by about 50 per cent over the next twenty years. He also forecasts that journey lengths will increase by 20 per cent and car occupancy will worsen by 10 per cent.3

The Environmental Transport Association (ETA), a "green" motoring organisation, advocates a number of policies, which it argues will lead to less dependence on the car and a greater emphasis on walking and cycling. Since 1996, the ETA has co-ordinated the UK's National Car-Free Day, held every year on 22 September, and some of the initiatives supported and promoted by the organisation include:

• rationing parking supply;
• rationing road supply as an alternative to congestion tax;
• congestion tax which is variable temporally as well as spatially;
• car-sharing;
• lower speed limits on roads, set by local authorities;
• improved public transport;
• better development and land use planning; and
• comprehensive cycle ways, built in consultation with potential users.

But transport is more than an environmental and health issue, it is also a social issue. Those members of society excluded from private car mobility - non-car owning households, people with disabilities, the young and the elderly, and those who can not, or choose not to drive - often have difficulty in accessing jobs and services, significantly affecting the social and economic opportunity of a huge number of people.

Modern culture is essentially a car-based culture, and altering the priorities of long and short-distance travellers will require a sustained and long-term effort. Local authorities have a strong role to play in implementing a number of actions on a local and national level to help ease the many problems. Some of these actions, which range from traffic reduction measures to using alternative fuels for council fleets, are laid out in more detail in the CIEH's transport policy.4

The range and diversity of local initiatives currently gaining momentum across Europe reflects a growing trend towards "grassroots" solutions. The WHO's Healthy Cities movement, for example, which aims to "bring cycling and walking into the mainstream of city transport policy and practice across Europe" already includes over 1,000 cities in networks across the region. The movement works with local government to increase cycling and reduce car journeys through the use of twinning and exchange of experience.5

Such initiatives can make a significant impact on people's health and arguably will provide the best means of moving the sustainable transport agenda forward. Not only will local people see the immediate benefits of cleaner air and healthier lifestyles, but these contributions will all feed into a national and international framework.

REFERENCES
1 Carlos Dora and Francesca Racioppi, WHO European Centre for Environment and Health, European Bulletin on Environment and Health, May 2001, page 2.
2 "A Sustainable Transport Convention for the New Europe" in Earth Summit 2002 - A New Deal, Earthscan 2000, page 111. (The ITDP is a US-based international research and advocacy NGO dedicated to promoting sustainable transport).
3 Environmental Transport Association's magazine Going Green, number 37, Winter 2000. For more information about this article and the ETA visit: www.eta.co.uk
4 The Chartered Institute of Environmental Health's transport policy document can be found here.
5 For information about Healthy Cities visit: www.who.dk/healthy-cities/transpor.htm

WHO are developing guidelines and methods for assessing the health impacts of cycling and walking on transport policies which will be made available in a form suitable for risk and health impact assessments. For more information visit the website: www.who.it/HT/teh.htm

CLEANER VEHICLE FUELS

Jonathan Murray, Director of TransportAction, looks at cleaner alternatives to petrol and diesel

The Energy Saving Trust (EST) is a non-profit organisation funded by government and the private sector with one main objective in mind - to reduce CO2 emissions in the UK. Over 25 per cent of man-made CO2 comes from transport, which is why the Government set up TransportAction PowerShift and TransportAction CleanUp, both DETR-funded programmes run by the EST. TransportAction delivers innovative solutions in a campaign to reduce the damaging effects of transport on the environment and seeks to promote sustainable mobility.

The TransportAction CleanUp campaign aims to improve air quality in pollution "hotspots" by encouraging the fitting of emissions reduction equipment to the most polluting vehicles such as buses and taxis. The programme will target the eight worst pollution areas in the country: London, West Midlands, Greater Manchester, West Yorkshire, Tyneside, Liverpool, Sheffield and Nottingham. With a budget of £6m in its first year, and a further £30m for the next three years (2001 - 2004), it aims to ensure that PM10 and NOx emissions are reduced as cost effectively as possible.

Launched in 1996, the TransportAction PowerShift programme has been set up with the aim of "kick-starting" the market for clean fuel vehicles (CFVs) in the UK. This includes vehicles powered by liquefied petroleum gas (LPG), natural gas (NG) and electricity. CFVs can reduce the output of CO2, the main global warming gas, as well as limiting the negative impact of vehicles on local air quality by cutting emissions of other pollutants such as NOx and PM10. PowerShift aims to transform the markets for clean fuel vehicles in the UK by breaking down the barriers to their development.

PowerShift has started this by developing a grant system that aims to reduce the capital cost of the LPG equipment. The scheme initially targeted fleets, thereby encouraging whole organisations to switch to LPG. In turn, these vehicles created local demand for the fuel and encouraged the development of the refuelling infrastructure.

Most petrol engines are suited to LPG conversions, and most diesel engines are suited to NG conversions. Electric vehicles have a much lower range than LPG or NG powered ones, and so are best suited to urban areas. LPG is the most popular alternative energy source, while interest in NG has been concentrated in heavy vehicle markets. Take up of LPG vehicles has so far mainly been from local authorities, delivery/courier companies, service engineers and sales fleets. The Government is further encouraging the use of clean fuels by lowering the duty on them. With the prices of clean vehicle fuels still very favourable, and the environmental effects underlined with every passing day, the case for clean fuels is proven.

WE'RE DOING OUR BIT

For retailer Safeway, its supply chain must deal daily with the challenges posed by congestion, emissions, noise and resource management. Minimising noise disturbance during store deliveries is a key environmental health priority and a number of initiatives have been pioneered in a bid to achieve this. Nitrogen refrigeration trailers service urban areas, such as London, while other noise amelioration measures include the use of liquified petroleum gas (LPG) to power refrigeration systems on trailers which operate at 64 decibels at seven metres (compared with an industry average of 69 - 72 decibels). "Good neighbour" principles mean that practices such as air suspension, air brake silencers, engine cloaking, silent night time reversing sirens and isolation of cab radios is normal procedure.

The company has also committed to the use of compressed natural gas (CNG) vehicles in recent years. In March 1998, Safeway started to carry out store deliveries in London and the Home Counties using ten CNG vehicles, made possible by a Powershift grant. In March of this year, the company decided to invest in an additional 40 CNG vehicles, and from the end of May, it will be operating diesel trucks that have been re-engineered to run on CNG. Early trials have proved encouraging. Compared with a diesel equivalent the CNG engine achieves 99 per cent reduction in carbon monoxide emissions, 75 per cent reduction in hydrocarbons, 86 per cent reduction in nitrous oxides, a 98 per cent reduction in particulates and an 11 per cent reduction in carbon dioxide. The engine is also 50 per cent quieter than the diesel version.

There is a problem, however, that the company believes is standing in the way of it being able to fully deliver the Government's sustainable development strategy. Nearly half of Safeway's stores are not permitted to receive night time deliveries due to local authority enforced curfews, which prevent deliveries from being made when roads are quietest. As Safeway points out, it is attempting to reduce its impact on traffic congestion, but the curfews only force deliveries to be made at the busiest times of the day.

Another consequence of the night delivery curfews, is the operation of a larger fleet in order to be able to service its urban stores. The company believes that the removal of curfews would enable it to reduce the size of its fleet by 12 per cent, as well improving fuel performance and therefore emission levels. Night time deliveries by clean and quiet vehicles to stores, coupled with considerate unloading practices would enable Safeway to alleviate traffic congestion, reduce CO2 emissions and improve air quality levels, thus helping to deliver local authority and company environmental objectives. Safeway would welcome the opportunity to explore this with local authorities.

TRAFFIC MANAGEMENT

New and important information is available that will help provide local authorities with the tools to manage local air quality. Dr Jane Cloke looks at the TRAMAQ programme

In 1998, TRL Ltd developed the TRAMAQ (Traffic Management and Air Quality) research programme for the DETR, with the main objective being to arm local authorities with some of the information needed to review, assess and manage the effects of road traffic on local air quality. The introduction of any traffic management measure produces effects on driver behaviour which, in turn, affect vehicle operation. For example, a road hump will cause drivers to slow down on the approach and accelerate away from the hump. The changes in vehicle operation affect the production of emissions, with possible implications for air quality. Finally, the changes that occur in air quality have an impact (eg health) on pedestrians, residents and drivers.

To predict the effect of traffic management on air quality requires an understanding of the way in which each of the steps is linked. The TRAMAQ programme focuses on:

• improved tools for estimating emissions from traffic;
• greater understanding of the contribution of road traffic to concentrations of NO2 and particles; and
• guidance on the effects of specific measures, such as traffic calming and parking controls, on emissions and the use of traffic management to control air pollution episodes.

The emphasis of the TRAMAQ programme is to gain a better understanding of the relationships between vehicle operation and emissions. One of the key problems in estimating the impact of traffic management on emissions is the lack of emission factors for vehicles travelling through traffic management schemes. To help address this issue, TRL is currently recording the operating profiles of cars, vans, buses and trucks travelling on roads featuring traffic management and calming measures. These profiles will then be used to develop improved emission test cycles and emission modelling procedures.

Estimating emissions from traffic also requires information on parameters such as vehicle type, age, fuel and engine size. An indication of the average distribution of these parameters across the UK can be obtained from national registration statistics, but the focus of traffic management schemes will be to remedy local air quality problems. It is costly to determine local traffic composition by direct observation, so TRL has carried out a desk study to develop a classification of traffic composition by geographical area and location type for use in local air quality assessments.

It is known that the majority of NOx emissions from road vehicles is emitted as NO, but it is estimated that a significant proportion could be as released NO2. Air quality measurements in many urban areas show that NO2 concentrations are about 20 per cent of total NOx. If primary NO2 emissions approach say, 10 per cent, this could be an important contribution to air quality. TRL is studying the effect of speed and engine load on emissions of NO2 through tests on a range of cars, vans, lorries and buses.

Although there has been much interest in airborne particles, there is still a great deal of uncertainty in the contribution that traffic makes to local concentrations. Some studies suggest that proximity to traffic has a relatively small effect on concentrations of particles, but inventories generally attribute most emissions to road transport. Either there are significant sources of particles that have not been accounted for, or the background contribution is proportionally larger than for other traffic-related pollutants.

Some air quality objectives relate to the control of peak concentrations, and are particularly relevant during periods of poor atmospheric dispersion. Radical solutions, such as banning traffic, may be needed. In certain situations, local authorities are seeking to discourage traffic in urban centres through parking controls, but it is unclear how changes in parking patterns affect emissions, particularly during the "cold-start" period when a vehicle's engine and catalyst are warming up.

Although traffic calming measures are designed primarily to improve road safety, it is also important for local authorities to be able to determine their impact on air quality. TRL has investigated the effects of a range of physical traffic calming measures on exhaust emissions. The results concur with earlier findings that such measures increase emissions from passenger cars, although the research shows that the increases are not as large as those reported previously, and are unlikely to result in poor air quality. The most severe measures result in the greatest savings for accidents, but also the largest increases in emissions. Local authorities need to balance the advantages and disadvantages of different traffic calming measures, and to do this, performance indicators have been developed to describe their effects on emissions, speed, safety, and delays to emergency vehicles.