EHJ October 2004, pages 316-318
The government has just published research telling Londoners where the capital is at its noisiest and where tranquillity can be found. Roger Tompsett and Liz Williams, from consultants Atkins, explain what was involved in putting together the world's biggest traffic noise map

The government has just published research telling Londoners where the capital is at its noisiest and where tranquillity can be found. Roger Tompsett and Liz Williams, from consultants Atkins, explain what was involved in putting together the world's biggest traffic noise map

The London road traffic noise map is just one element of the government's much wider national ambient noise strategy.

It provides information on the levels of road traffic noise across the whole of the Greater London Authority's area. Other types of noise will be covered by projects that are being planned or progressed at present.

Although road traffic noise is only one type of noise affecting people, it is a concern for more Londoners than any other source of noise. In the London household survey undertaken by the GLA in 2002, 13 per cent of Londoners said that road traffic noise was a serious problem. This compared with 6 per cent who cited aircraft noise and 4 per cent who considered that noisy neighbours were the problem. At the same time, it was felt there was a need to protect existing areas of tranquillity.

Noise maps help to establish an existing baseline so that the effectiveness of future initiatives to control noise can be measured. They also allow us to see how noise spreads from roads into residential areas and how different types of building layout affect the spread of noise. Noise maps also highlight the havens of quiet that already exist within the city and show how careful planning could create more of them.

Noise maps will help non-specialists develop a more intuitive feel for how noise behaves, which will allow more people to appreciate the importance of planning and designing against noise and to let them become involved in the process. They will also give experts the tools to refine designs for maximum benefit at affordable cost. The London road traffic noise map is the first detailed noise map for the whole of Greater London and will necessarily be limited by the availability of some types of information.

But at the same time, it has formed a focus for gathering together the huge body of information already available into a coherent set of data. The map is a live resource that can answer many of the questions which will arise as people continue to look for measures to better manage the noise we generate.

One measure of the success of the project has been the extent to which the local authorities and other stakeholders became involved. They contributed by supplying additional data to help construct the map, reviewing a draft copy and by developing a detailed appreciation of the map and how it can be used.

STAKEHOLDER LIAISON

Stakeholder events were held during the course of the project to inform stakeholders of its progression and to enable them to provide feedback to the project team. Events were held in City Hall from December 2002 to October 2003. Interest in the project grew with each successive event, with stakeholders becoming increasingly keen to make use of the map as they became aware of its potential.

Newsletters were also published and distributed to all the stakeholders - one in June 2003 following the completion of the pilot area noise map and the second in spring 2004 following completion of the main mapping exercise.

A website (www.londonnoisemap.com) was set up. This attracted a lot of interest, especially after BBC TV London News broadcast a short news item on the noise map. Abstracts from the website appeared in a number of places, including a half-page article in the Guardian.

A website has been created which will allow people to view the finished noise maps using an ordinary web browser. Users can select any area of the map by postcode, street name or OS coordinates to view the noise maps at small, medium or large scale. This is available at www.noisemapping.org

Training courses were held during the second half of the project. The basic courses were presented at 18 of the 33 London borough offices to enable as many interested staff as possible to attend. The more advanced hands-on computer training courses were held at the Atkins office at Euston Tower in central London. These courses were attended by a total of 58 people representing 22 boroughs, Defra, Schal International Management (the project management company) and the GLA. The courses were also held at a special training day at the Transport for London offices.

All stakeholders were given an opportunity to install a copy of the NoiseMap Server Edition software at their offices and to use it for a limited period free of charge to study the noise model and map. Twenty-eight of the 33 London boroughs requested a copy of the NoiseMap software during the project.

Interest was shown in the project by 32 London boroughs, through attendance at events and/or training courses. These stakeholders were, in general, very impressed with the information that the London road traffic noise map could provide. Most boroughs hoped that they would be allowed to use the map interactively and were particularly interested in using it to assess the impact of future developments.

EHPs were keen to use the map as a powerful tool for assessing planning applications in accordance with PPG24 guidance, and to help planning departments prioritise planning applications by publishing an image of the map noise contours, coloured into PPG24 categories.

Highways and traffic engineers from some boroughs also became involved, mainly by attending training courses held in borough offices, with a few following this up by coming along to the hands-on training courses. They found that the software actually gave them a very easy interface by which to view the traffic information, using the view-as-colour tool in the software.

Some boroughs even brought current planning applications along to the hands-on training course to learn how they would put that information into the model and calculate its impact.

CREATING THE MAP

Quality information on traffic flows was central to the project. The London atmospheric emissions inventory (LAEI) provided details of traffic flows to include in the model, with a first approximation of the location of the roads. This was processed in a geographical information system (GIS) to give the required geographical accuracy, and the traffic flows were converted into the form needed for noise calculations. A GIS programme was designed to calculate the road widths from the Ordnance Survey master map. The roads were categorised into types so that the contribution of noise from different parts of the road network could be shown, eg motorways and the primary route network.

TRANSFER OF THE DATA TO THE NOISEMAP DATABASE

Atkins' NoiseMap SE software was used for this project. One of its strengths is its ability to work with GIS data. Information can be fed directly into NoiseMap in the form of shapefiles (used by GIS), where it can be converted into the objects used by the calculation of road traffic noise (CRTN) methodology. In addition to the road data, further data files provided the locations of buildings, man-made slope features and the position of features that delineate hard and soft ground, taken from the ordinance survey master map data. The information is all stored in the NoiseMap database, which allowed a large number of computers to collaborate on the calculation process.

The database is visible from the internet and in the later stages of the project the local boroughs and other stakeholders, with suitable software, were able to access the model and interact with it.

The ordnance survey profile ground level contours form the baseline for the creation of the three-dimensional world inside the NoiseMap software. However, it is not capable of supplying all the height information that is needed. For extra details, road and earth-work height data was obtained from aerial photography which was then processed by Atkins Photogrammetry (stereoscopic analysis).

COLLECTION OF DATA "ON THE GROUND"

It was important to gather local information about non-standard road surfaces, roads that deviated from ground level and purpose-built noise barriers. A data request event was held which a majority of stakeholders attended. The boroughs were issued with maps to be marked up with the locations of non-standard road surfaces and roads that were not at ground level. These maps were then returned to the project team so that the local information could be added to the model.

Apart from purpose-built acoustical screening and the impact of terrain and landform, the main barriers to noise propagation in the urban environment are the buildings themselves. Each and every building that potentially has a screening effect must be included in the noise calculations as a "barrier" object. Each acoustically significant building is processed during the calculation. For this project it was decided that, in the absence of data for the whole London area, the buildings would all be modeled at a height of 8m above local ground. Considerable effort was made to ensure that actual building heights can be added later, as soon as the information becomes available.

STAKEHOLDER INTEREST IN THE PROJECT

Following the end of the project, several boroughs have purchased noise mapping software and access to the NoiseMap database.

The overall approach to the project is considered to have been very successful. It has delivered a high quality noise map on time and to budget and most stakeholders have participated in events and training with enthusiasm, and have acquired a temporary copy of the software to try out the system.

The understanding of noise mapping by all parties - including the project team - has increased considerably as a result of this noise mapping exercise. To view the noise map go to Defra's web site at www.noisemapping.org.