Local authorities, faced with improving air quality, will no doubt look to action plans that have transport measures at their core. Dr Guy Hitchcock explains how a clear zone can help rid an area of the negative impacts of traffic

Air quality and the urban environment is high on the Government's agenda and over recent years there have been a number of wide ranging policy developments in these areas, including: the Environment Act 1995 and the requirements of the National Air Quality Strategy, now embodied in the National Air Quality Regulations 2000; the Integrated Transport White Paper and the consequent Transport Act 2000; and most recently, the Urban White Paper.

All of these policy initiatives recognise the inextricable relationship between transport and the urban environment - both in terms of economic activity and environmental and social damage. With respect to local air quality, local authorities are required to assess air quality in their areas with regard to the national objectives, and if exceedances are expected then an Air Quality Management Area (AQMA) must be declared. Local authorities must then adopt an action plan, with respect to the AQMA, to mitigate the problem, which must have regard for other planning policies in the area and non-air quality impacts.

In most cases, some 95 per cent, AQMAs are expected to be related to traffic. Therefore, action plans will need to be focused on measures to reduce the emissions from transport activity. Although understanding and measuring the air quality problem falls largely to environmental professionals, finding the solutions will require a major input from transport professionals.

EMISSIONS AND TRANSPORT PLANNING
There is a direct, but not necessarily simple, relationship between vehicle exhaust emissions and air quality in most urban centres. At a basic level, to improve air quality in these areas vehicle emissions have to be reduced. In order to reduce exhaust emissions there are three basic actions, the likely magnitude of which follows this order:

• reduce the amount of vehicle activity in an area, which will have a direct reduction on the emissions produced;
• alter the type (size, technology, etc) of vehicles operating in the area; and
• change the way vehicles are driven (speed, acceleration, etc). If enough people follow suit, this can be significant.

It is not only the absolute impact per vehicle that is important, but the number of vehicles involved. For example, if only vehicles meeting Euro II emission standards were allowed to operate in an area (and assuming this did not reduce the number of vehicles operating) a 30 per cent reduction in emissions might be achieved, which would be greater than removing 10 per cent of the traffic. In reality, local authorities should be looking to implement a complementary package. In order to achieve the necessary reduction in vehicle emissions, innovative and potentially radical solutions need to be adopted in relation to the wider urban context to ensure that they are accepted and prove successful.

THE CLEAR ZONES CONCEPT
The "clear zones" concept grew out of the Government's "Foresight" programme, which seeks to identify how society is developing, what its future needs will be and how we can support technologies and initiatives to meet these needs. Identified as a generic approach to achieving the city centres of the future, a clear zone is a well-defined city area where a proactive approach is taken to "clear" the area of the negative impacts of traffic. This includes congestion and delays, poor air quality, noise and other environmental impacts, and physical intrusion in terms of safety, use of space and visual impacts.

The clear zone seeks to reduce these impacts in two main ways. First by reducing vehicle use within the zone as much as is practicable and second by ensuring that necessary vehicle use is as clean and efficient as possible. Importantly, a clear zone seeks to use new technology and innovative approaches to achieve this. Perhaps the two most important groups of technologies in this respect are IT systems for managing vehicle access and information, and clean vehicle concepts such as gas, electric and hybrid vehicles. Within the generic description of clear zones, there are a number of concepts including car free zones, low emission zones and access controlled and pedestrian zones.

REDUCING TRAFFIC
In terms of reducing vehicles there are two main actions to consider:

• removing unnecessary vehicles - in terms of vehicle types and trip types; and
• providing alternatives to ensure good access to the clear zone.

There are four issues to be considered with regard to removing unnecessary vehicles:

• through traffic, which does not really contribute to the clear zone in terms of delivering people for retail, leisure or commercial reasons;
• vehicle hierarchy, which allows the focusing of measures to reduce activity of the least preferred vehicle types and promotion of the preferred vehicle types. Typically, pedestrians would be first on the list, cyclists second, public transport third, goods vehicles fourth and private cars last;
• access control and management; and
• time-of-day restrictions.

Through traffic is probably the least necessary of all vehicle movements, providing no economic benefit to the centre and contributing significantly to the impacts of traffic. Therefore, this is the traffic activity that most clear zones and city centres will try to remove first. The approaches to removing through traffic usually involve signage and the designation of specific through traffic routes, an approach which is fairly widespread, and specific vehicle restrictions. This latter approach is seen as increasingly necessary as simple signage is not proving sufficient. A good example of this approach is the development of city centre access cells which allow vehicles to access different parts of the area, without a direct through route.

In managing vehicle restrictions, some kind of access control or management system is required. Such systems should consider not only the type of vehicle but also the user, and can range from full pedestrianisation to restrictions that allow only public transport vehicles and taxis and sophisticated systems that allow access on the basis of user and/or vehicle type. There is also the issue of restrictions at different times of the day. It may not be necessary to restrict vehicles for 24 hours - there may not be a traffic or environmental problem at certain times of the day and full restrictions may hamper effective access to an area.

PROVIDING ALTERNATIVES
One of the criticisms certain to be levelled at local authorities if they try to reduce vehicle use in the city centre is that it will harm the economy and vitality of the area. Although there is much experience to suggest this is not true, and in fact the opposite may be true, it is an issue that should be dealt with proactively. It is people, not vehicles, that need access to the clear zone to maintain and increase the vitality of an area. To ensure this access is maintained, people need alternatives to the private car. This implies the provision of an efficient public transport system, good integration between different modes and good information that allows people to use the alternatives confidently. A good public transport service needs to provide not only links to the clear zone but also within it.

In terms of transport, people need a door-to-door travel option and this may not be met with a single public transport service. Therefore, public transport options serving the clear zone need to be integrated smoothly with other services and modes. The key interactions are:

• park and ride (both bus and rail based);
• bus-to-bus interchanges (to ensure efficient multi-stage trip across the city);
• rail-bus interchanges (to ensure that passengers from rail stations outside the clear zone can be delivered efficiently into the clear zone); and
• good cycle and pedestrian links to both bus and rail stops.

The key to successful multi-modal and multi-stage trips is reliable services and good information, including:

• trip planning information, from call centres, printed timetables and internet based trip planner; and
• real-time information about vehicle arrival times at bus stops and stations.

CLEAN AND EFFICIENT VEHICLE USE
In most clear zones, although there are unnecessary vehicles and trips that a local authority should seek to remove, there will also be necessary and even desirable vehicle activity to ensure that the centre is accessible. The objective with this vehicle traffic should be to make it as "clean" and as efficient as possible. Three particular measures that can help achieve this objective are:

• the use of "clean" vehicle technologies and fuels;
• vehicle priority and space management; and
• co-operation and flexibility between transport operators and services.

CLEAN VEHICLE TECHNOLOGY
The core groups of vehicles that will be needed in clear zones are public transport vehicles and freight and service vehicles. These vehicles can be made considerably cleaner by the use of new vehicle technologies and fuels, including:

• retrofit equipment for existing vehicles, such as particulate traps and catalysts;
• gas fuelled vehicles, covering both liquid petroleum gas (LPG) and compress natural gas (CNG); and
• electric, hybrid and fuel cell vehicles - which provide the cleanest option for urban use, but are still developing. Good examples of light duty vehicles exist, but the technology is more difficult for heavy vehicles and buses.

The Government is actively supporting the development of the market for these vehicles and fuels through the Energy Saving Trust TransportAction initiative (see page 175). This provides grant funding for new vehicles, conversion and help with the cost of refuelling infrastructure.

Local authority vehicles can also play a strong role in encouraging these vehicles through public transport and freight quality partnerships, priority access and parking for clean vehicles and by supporting the development of a refuelling infrastructure. A good example of priority for "clean" vehicles is the concept of low emission zones, which is starting to develop in this country. Ideas are being considered for some of the London boroughs, Nottingham (on a more voluntary basis), Leicester and Bath.

PRIORITY SYSTEMS
One way of increasing the efficiency of vehicles allowed access to the clear zone is to ensure that they get adequate priority. The most common example of this is the use of bus priority systems, both physical (bus lanes) and active (such as priority at traffic lights and junctions).

Another area, often forgotten, is the provision of efficient access for goods and service vehicles. Freight vehicles parked on narrow roads and pavements while unloading cause severe congestion. Some of the priority issues that need to be considered are the introduction of signing and guidance systems to direct freight vehicles and specific freight loading bays so that traffic flow is not interrupted.

FLEXIBLE OPERATION
Efficiency of vehicle operation can often be improved by co-operative and flexible working arrangements between operators. Some of the ideas that can be considered include urban transhipment centres for goods delivery, fleet share and service sharing, and co-operation between modes.

There are occasions when vehicles and services overlap and could be co-ordinated better. A good example of this is with community, social services, hospital transport and accessible bus services. It can be possible to get significant savings in terms of both cost and vehicle usage in co-operative work. This was trialed successfully in Camden with Camden Community Transport which co-ordinated a range of community and other services in the borough. The key to the success of these activities is the use of good management systems for booking, vehicle tracking and information management. For example, it may be not be necessary to provide a dial-a-ride from door to door, but merely as a link to an appropriate accessible bus service.

Co-operation between modes can also have an important role to play to ensure that the right vehicle/mode is used for the right trip. Why run a bus for two passengers when a taxi would be more efficient, or take a taxi when a bus route would serve your needs? Co-operative working in this way needs to break down a lot of barriers between operators, but can be highly effective.

The clear zones concept has a common goal with air quality action plans, in that it seeks to provide an area where, through a package in innovative transport measures, traffic congestion, pollution and other negative impacts of mobility are limited. A clear zone is an area management scheme and, like an AQMA, it should be integrated into local planning documents, such as the local plan and local transport plan, to provide a basis for managing activity.

In most cases, direct traffic management will be carried out through traffic regulations to manage access and activity within the area. A clear zone also promotes innovation and new technology by pushing the boundaries of conventional transport thinking, taking the long-term view and using new technology developments to help achieve its goal. In many cases, it is new technologies that are now making these changes possible.

Clear zones is also an integrating concept. Being wider than just air quality, clear zones provides a framework to integrate a number of urban policies within a defined city area. In particular, it pulls together air quality and pollution, road traffic reduction, integrated transport and urban regeneration. It tries to create a virtuous circle of improvement through the reduction of the number of vehicles in an area which then allows the allocation of more space for human based activities.

Dr Guy Hitchcock, clear zones co-ordinator, Transport and Travel Research, 6 Portland Square, Bristol, BS2 8RR. E-mail: guyh@ttr.globalnet.co.uk

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