Essex Highways worked with Maldon District Council and Essex County Council to identify the causes of high nitrogen dioxide concentrations within the Market Hill Air Quality Management Area, and to develop, assess and implement a solution.
Introduction
An Air Quality Management Area (AQMA) has also been declared along Market Hill in Maldon, which is primarily attributable to road traffic emissions. Essex Highways, Maldon District Council (MDC) and Essex County Council (ECC) have worked together to understand the causes of high monitored nitrogen dioxide (NO2) concentrations within this AQMA, and to identify and implement a solution.
Method
A traffic and Automatic Number Plate Recognition (ANPR) survey was undertaken in 2021 to understand road traffic movements in this area and to inform the future transport strategy for Maldon. Data from the Driver and Vehicle Licensing Agency were obtained and assigned to each of the number plate records captured during the survey to understand the vehicle type, fuel type and engine emissions standard of vehicles travelling in this area. These data were then analysed by Essex Highways to estimate the contribution made by different vehicles to road traffic emissions on Market Hill.
Result
The outcomes of the ANPR data analysis indicated that heavy goods vehicles (HGVs) and buses have a disproportionately high impact on local NO2 concentrations for their relatively low number of trips. Their impact, and the impact of all local vehicles, is exacerbated by the local environment. Market Hill has a steep slope, resulting in additional engine load for vehicles travelling in the southbound (uphill) direction, and further to this, the close proximity of nearby residential properties reduces the dispersion and dilution of road traffic emissions.
Using this information, Essex Highways’ Transport and Air Quality specialists developed bespoke mitigation measures, targeted at reducing emissions from HGVs and buses on Market Hill. A sifting workshop was held, the outcome of which was a short-list of measures to be assessed in more detail using traffic and air quality modelling. Two measures were identified as feasible and likely to reduce NO2 concentrations on Market Hill without increasing NO2 concentrations elsewhere: additional signage and communications so that HGVs are more likely to take alternate routes (e.g. the A414) instead of through the centre of Maldon via Market Hill, and improvements to the local bus fleet to make them cleaner.
An additional scenario was assessed using the traffic model only, which was making Market Hill one-way in the northbound (downhill) direction. However, the traffic modelling showed that banning the uphill traffic on Market Hill caused significant delay and congestion within Maldon, so this intervention was not taken any further.
Next steps
The next step for the project is to implement the two measures that were found likely to improve air quality on Market Hill. This will comprise the development and installation of signage, and liaising with bus operators to most efficiently improve the fleet on Market Hill.