The highway authority raised concerns regarding the accuracy of the transport modelling including the distribution and assignment of trips through various junctions, the reliability of traffic count data, the cumulative impact of other developments in the area, road safety information and proposed off-site highway improvements.
In agreeing that trip distribution and assignment did not appear to have been correctly modelled, the inspector also noted that the impact of trips from other schemes had not been fully considered. In particular, the appellant’s transport evidence proposed mitigation at one junction which had not been examined in the transport assessment and the planned improvements would not be able to ensure that buses and heavy goods vehicles could safely queue and manoeuvre. Nor had planned improvements at another junction, which the appellant had committed £250,000 towards implementing via a planning obligation, been accurately costed because no detailed scheme had been prepared or agreed.
The traffic generated by other schemes was a relevant consideration, the inspector held, but in some cases these had not been correctly included in the modelling, with some trips having been omitted altogether. Third parties had also commented on the level of congestion on local roads, and applying the precautionary principle set out in Satnam Millenium Ltd v Secretary of State for Housing Communities and Local Government and Warrington Borough Council , she was not satisfied that there would not be an unacceptable effect on highway safety or a severe cumulative impact on the road network. Therefore, while the tilted balance in paragraph 11(d) of the NPPF applied, because the most important policies for determining the application were out of date, she concluded that extremely substantial weight should be given to the potentially adverse impact on highway safety, and the appeal was dismissed.
Inspector: Katie McDonald; Inquiry