EFFECT -
Environmental Forecasting for the
Effective Control of Traffic

Keywords: Urban air quality, traffic management, decision support system
Application site: Leicester and Maidstone, UK; Goteborg,S; Volos, Gr
Website: www.tol.hol.gr/business/effect
or www.park.westnet.se/lufnet
E-mail: nick.warren@kent.gov.uk or
nhodges@lccatc.demon.co.uk (for the Leicester site)

Context
The project includes four European cities willing to improve air quality through a more efficient traffic management and control. Each of the participating cities were chosen because of the availability of selected expertise, available infrastructure and contrasting conditions.

With a population of 120,000, Volos is Greece's third largest port and is situated between its sea and mountains. These factors, combined with the traffic conditions, have given rise to concerns over air quality, resulting in a political desire to improve the situation. Volos' Mediterranean climate is in stark contrast to the Swedish city of Gothenburg with its population of 430,000. Gothenburg, one of the leading cities in the field of air quality management, also hosts the ARENA transport/IT test site. Maidstone, with its 120,000 inhabitants,has an advanced traffic control system and is currently implementing a county-wide strategic pollution monitoring system under the LIFE funded MIST Programme.

Leicester has a long history of using state-of-the-art traffic control systems and has received political support for implementing management strategies within the 470,000 population conurbation. Leicester had been developing an Urban Traffic Control (UTC) based system for controlling the movement of traffic. The infrastructure ranges from Fixed Time Control to Split Cycle and Off-set Optimisation Technique (SCOOT) operation. Research experience has been gained by collaboration with numerous University Research projects especially using the Instrumented City facility, developed with the University of Leeds. The UK Department of the Environment had commissioned the City to operate an Automated Urban Network monitoring station to complement existing simpler systems. As the UK's First Environment City, members want to be leading the way towards ensuring that the City meets the relevant Air Quality-Standards in advance of the implementation of National values.

Objectives
The project targets can be summarised in the following points:

Results
The results of the project are the forecast of poor local air quality in real or near real-time, and to highlight air pollution 'hot spots'. This is achieved by integrating air quality modelling with real time information on traffic flow s, pollutant concentrations and meteorological conditions and an emissions database. Air pollution hot spots are needed to instigate effective Traffic Demand Management Strategies (TDMS) in order to reduce pollution levels in particular polluted areas. This is being achieved through the implementation of local Environmental Management Boards (EMB – a consultation forum for assessing the acceptance of alternative strategies).

In Maidstone, Kent, a local Environment Management Board has advised on the strategies to be adopted by the network managers and then traffic demand management strategies. Daily air quality predictions are produced for CO, NOx, O3, PM10, and SO2, to assist network managers to control the daily movement of traffic. In Leicester 24 hour and 48 hour forecasts are broadcast and used to assist in traffic demand management.

The availability of traffic data and air quality modelling lies at the core of the system. In the two UK sites, the traffic data is obtained from the demand-responsive SCOOT (Split, Cycle and Offset Optimisation Technique) urban traffic control system. In Gothenburg, the ARENA traffic monitoring and modelling system is used. In Volos, a fixed-time urban traffic control system is used in conjunction with flow counters. The air quality modelling in all four sites is being carried out using the AIRVIRO system marketed by SMHI in Sweden. The Eulerian Grid Model is used for the prediction of gaseous particle dispersion, except in Volos where the Gaussian Model is deployed. A Street Canyon model is also available. The EFFECT system architecture allows the use of any other similar air quality model.

In Leicester the AIRVIRO model has been enhanced with 'real-time' traffic data (plus a database link to a traffic model) and transferred to Gothenburg where the existing air quality and traffic systems are linked. In Maidstone traffic demand management strategies have been enhanced, while in Volos a basic AIRVIRO system has been installed and advice on the development of simple traffic demand strategies are provided.

To address these problems, the approach of EFFECT is to optimise the infrastructure required (i.e. deployment of monitoring equipment versus modelling techniques) to adequately support Air Quality Management, compliance with Statutory requirements and provide the administration and public with information to allow proper choices and actions to be taken by all, with the objective of protecting the environment and thus the quality of life.

Technical characteristics
The enhanced AIRVIRO Air Quality Model gives near real-time predictions of Air Quality to be used together with Traffic Demand Strategies to reduce pollution levels. The objective is to reduce pollution by providing in simple graphical format "near-real-time" air quality information and traffic demand strategies to assist network managers to control traffic movements.

It consists of enhanced AIRVIRO (Grid or Gaussian and Canyon models) to match infrastructure and data available to suit the local needs. An HP Workstation plus Meteorological Mast and Monitoring equipment (or data to suit accuracy of output required) is required.

THE AIRVIROSYSTEM
At the heart of the system is a computerised map containing the topography and land-use across the area.AIRVIRO requires information about the major sources of air pollution in the area (point sources – factories, offices, shops -,area sources – housing or industrial agglomerates – and line/road sources). Dynamic and static information is collected for each source. Dynamic information includes formulae which describe the emission as a function of outdoor temperature or as a function of day, week and time. Static information covers chimney height, exhaust gas temperature, co-ordinates, etc.

Road sources information can be obtained from a traffic model or from direct observations. In Gothenburg, the coastal sea lane is also an important line source.

The road network data was obtained from a TRIPS traffic model in Leicester, a CONTRAM model in Gothenburg, and a SATURN model in Maidstone and Volos. The traffic model gives information on the location of the roads, the number of vehicles in the peak and off-peak periods, and the speed limit of the roads. Standard emission rate information for the different vehicle types was then applied.

Once the AIRVIRO system is established, it is then possible to carry out air quality modelling to assess the effect of the various traffic demand management strategies developed in the project. However, it is not possible to be totally confident about the accuracy of the concentration figures produced, unless some air quality and meteorological monitoring is also undertaken.

AIR QUALITY AND METEOROLOGICAL MONITORING
The four sites in the EFFECT project use the AIRVIRO system to perform this function. There is a wide range of monitoring equipment used at project sites. Meteorological monitoring was also performed using a meteorological mast, measuring vertical and horizontal wind speed and direction and air temperature. The measurements helped to build up a database of local weather conditions and to carry out air quality predictions for various weather scenarios.

TRAFFIC DEMAND MANAGEMENT STRATEGIES (TDMS)
These have been developed using the SATURN traffic model in conjunction with AIRVIRO. The EFFECT PLUS project is providing TDMS for Leicester, whilst Gothenburg will use ARENA with EFFECT for TDMS. These strategies may include holding traffic outside the city, metering, gating, advisory diversions or closing roads. Information is given to the drivers using tools such as Variable Message Signs, radio broadcasts using RDS/EON (radio data system/enhanced other network) technology and PROMISE 2 terminals.

The appropriate strategy is selected by the traffic control system operator based on the available air quality modelling information and their own experience of traffic conditions in the network. The effectiveness of the implemented strategy can then be assessed using modelling, if monitoring has also been carried out.

REAL-TIME LINKS BETWEEN TRAFFIC MONITORING AND AIR QUALITY MODELLING
The AIRVIRO system is given information about the average daily and seasonal flow profiles of the traffic. However this information is only good and up-to-date if the model which generated it is continuously updated with near real-time data. The Leicester SCOOT system has developed such a link and this is demonstrated also in Maidstone and Gothenburg. Thus, instead of using the modelled values, AIRVIRO can produce air quality predictions which are based on actual traffic levels. The results of these predictions are updated and displayed every hour.

THE EMMA/EFFECT CYCLE
In Leicester, the EFFECT project has been carried out in conjunction with another TAP-EN project called EMMA.

The focus of EMMA is on predicting air quality and providing information to the public as well as to network managers. The UK Meteorological Office provides 60-hour weather forecasts direct to the AIRVIRO database to enable 24 and 48 hour air quality forecasts to be made. This tie-in with EFFECT means that if the air quality conditions are known for the following day, then appropriate demand management strategies can be selected to reduce the impact of a potential air quality problems. EMMA uses the weather forecast together with the enhanced AIRVIRO database to forecast tomorrow's pollution levels. The forecast is used by the network manager to select an appropriate TDMS, including regulatory restrictions The forecast is also broadcast by radio during the afternoon and evening when people return home.

Given this information, they can choose how or when they will travel into the city the following day. The next morning, EFFECT will predict the current pollution levels, allowing the network manager to review the TDMS for the afternoon if necessary.

Transferability
The experience gained within EFFECT with transfers to and from Leicester, Maidstone, Goteborg and Volos of the various modules and protocols shows that the basic concept can be transferred to both a simpler or more sophisticated environment in a variety of meteorological climates covering Scandanavia, Atlantic Europe and the Mediterranean. Goteborg had the sophisticated Air Quality Monitoring and Modelling experience. Leicester had both simple and sophisticated traffic control systems. Maidstone had a regional air quality monitoring/planning collaboration. Volos had limited traffic control and air quality monitoring. The project experiences make it easier to offer realistic advice to reduce total investment.

The project is very relevant outside of its current scope of implementation, as the aforementioned examples of Goteborg/Maidstone and Volos show. There are no special extra costs for transferring the application. Simpler existing infrastructure will involve the acceptance of cruder outputs. N o elements appear to be site exclusive to the application and all seems transferable .

 
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