Experts from Imperial are building the traffic models that drive a new water pollution management tool.
When we talk about pollution from road traffic we usually mean air pollution, with gases and particles from internal combustion engines the main culprits. But roads can also cause water pollution, with toxic material from vehicles and other sources washing off the road surface and into ditches, streams and rivers, where they can harm wildlife and undermine drinking water quality.
Imperial experts are helping develop an online tool that could enable local authorities to tackle this problem by predicting water pollution hotspots and planning measures such as wetlands, ponds and rain gardens to mitigate the problem.
The researchers, from Imperial's Centre for Transport Engineering and Modelling, are working independently via Imperial Consultants on a series of projects for environmental charity Thames21.
"Reduction of discharge into rivers or streams is one of the most important factors in managing pollution," said a spokesperson for Thames21. "So, developing this collaborative Road Pollution Solutions Tool to help local authorities identify problem areas in order to help them place nature-based solutions in those areas is a step in the right direction."
Maps and modelling
The Road Pollution Solutions Tool started out as an online map developed by Thames21, Middlesex University academics and other partners, which shows the risks of water pollution from busy roads in London. The tool combines factors that contribute to the accumulation of pollutants on the road with data on local rainfall conditions, the surface area of the roads and the kind of traffic on particular routes.
The traffic data initially used to build this tool only covered the main roads in the capital. The Imperial team was brought in for a second phase of the project to model the road network much more comprehensively, predicting traffic flows even for roads where recorded traffic data was not available.
"We used our knowledge in this domain to identify the spatial characteristics that were most related to the amount of road traffic within this road segment, and where the modelling gaps were," explains Dr Liang Ma, a research associate at the Centre, which is part of the Department of Civil and Environmental Engineering. "We know that the city is a very complex network, so the impact pathway will not be a simple one. It will not be linear or additive. In this case, we have to use a more advanced model."
As well as filling in the data gaps for London, the Imperial researchers extended the area covered by the Road Pollution Solutions tool with an annual average daily traffic model for the Maidenhead-Teddington catchment area and for Surrey.
Two-way streets
The current phase of the project, led by the British Geological Survey, will see a further expansion to include the Upper Thames catchment. This is an area that takes in the city of Oxford, many smaller towns, and sections of the M4 and M40 motorways. The expanded tool will also factor in run-off from agriculture, a significant problem given the extensive farming in the region.
The Imperial team, meanwhile, will refine its model further. "We are incorporating spatial correlation in traffic and accounting for complex influencing factors, such as nearby population, proximity to the city centre and whether a road is major or minor," said Dr Ma. "All of this can be done using open-access UK government datasets."
We collect data every day and we need to find a better way to use it and to support our future. Dr Liang Ma Centre for Transport Engineering and Modelling
While developed for water pollution, this traffic modelling could form the basis for other informative systems, Dr Ma said. "For example, we can estimate the air pollution, the greenhouse gas emissions, and areas that simply have a large volume of traffic where maintenance or road safety measures might be needed."
They might even inform the design of future road networks. "In road planning these models can be used to see the potential for maximum traffic and inform the government about road capacity." Ultimately it is about making use of the information that we already have. "We collect data every day and we need to find a better way to use it and to support our future," Dr Ma said.
The Road Pollution Solutions tool for outer London can be found on the Thames21 website and the British Geological Survey website.
