Reasoning behind 60mph limit M5 Junction 1 Southbound - Junction 3
Case reference EIR2025/00814
Received 27 April 2025
Published 3 July 2025
Request
After reviewing the National Highways consultation document on the permanent 60mph speed limit between Junctions 1 and 3 of the M5 motorway, several critical concerns emerge regarding the justification and methodology behind this decision.
Response
The decision to implement the 60mph speed limit on this section of the M5 is based on two key considerations.
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There was an established exceedance of the annual mean nitrogen dioxide (NO2) limit value at a qualifying feature (residential properties in this instance) within 15m of the M5. Please see the modelled annual mean NO2 concentrations for Census ID 46015 in Table 5 on page 27 of the report (https://s3.eu-west2.amazonaws.com/assets.nationalhighways.co.uk/Air+quality+progress+update/I ndex/Commission+1/Phase+3+AQ+Report/Phase%2B3%2BAir%2BQuality%2B Report%2Bv4.pdf)
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The existing speed limit on this section of the M5 was set at the national speed limit i.e. 70mph for cars and vans. Research undertaken by National Highways showed that reducing the speed limit from the NSL down to 60mph could lead to approximately 17% reduction in tailpipe emissions for cars and vans (http://assets.highwaysengland.co.uk/CPC_Speed_Band_17092019_v2.pdf). Air quality modelling based on this change in emissions lead to a reduction in roadside NO2 concentration, as presented in Table 7.2 for Census ID 46015, and this level of change would help bring forward compliance with the NO2 limit value.
Documents
This is National Highways' response to a freedom of information (FOI) or environmental information regulations (EIR) request.
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