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Severe ‘Whether’ Warning

Is this a severe warning whether a key transport paragraph of the National Planning Policy Framework will ever be fully understood, or does a recent research paper represent a bright and sunny future for the transport planning industry? Transport Director, Simon Moon, gives his view.

Since the first publication of the NPPF there’s been one paragraph that has had Transport Planners scratching their heads. Back in 2012 this was paragraph 32 and in the latest version paragraph 109. Although the words have been tweaked over the years to give a greater focus on highway safety impacts, the thrust has stayed the same and reads:

“Development should only be prevented or refused on highways grounds if there would be an unacceptable impact on highway safety, or the residual cumulative impacts on the road network would be severe”. 

It is these words which have been the subject of many debates between Transport Planners, Planning Officers and the like for as long as they have been published, and the reason is how do you determine: what is severe?

To explore this in more detail I attended the 17th  Annual Transport Practitioners Meeting in Oxford last month. A paper titled “What is Severe” was presented and this aimed to address the question many people have been asking for some time.

The presentation opened with an assessment of the challenges and what is hoped to be achieved. In summary the goal is to provide an easy-to-use, efficient and practical toolkit capable of indicating what is severe. The toolkit will consider a number of points including both safety and reliability with the focus on the former.

It was however acknowledged at the end of the presentation that more research needs to be undertaken, and it was this (following a strong coffee in the break), which pushed me to approach the author.

We discussed that severe is not only subjective but also relative to the local environment. That is to say that an estimated increase of ‘X‘ minutes in traffic delay as result of development may be totally acceptable in one area, but viewed as detrimental elsewhere. Furthermore one has to ask: can individual planning aspects, for example an increase in queue length, be considered in isolation with regard to a binary severity test, when planning is, by its very nature, a holistic subject?

So what does this all mean?

Well until further work (possibly much more work) is completed there is still no answer to the question regarding development impacts on the highway and what is severity. Transport Planners will still need to look at the individual situation and use the current modelling software to the best of their ability, whist being mindful of all other facets of the planning system – and it is with this in mind that I believe DHA is well placed to help our clients. It is my view that combining both Town Planners and Transport Planners ‘all under one roof’ provides us with a unique opportunity to serve our clients in this complex policy situation.

If you have a project which is experiencing issues such as those outlined above, please do not hesitate to contact me for further advice.

For more information call 01622 776226 or email:

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