TRAFFIC CALMING AND AIR QUALITY

Following the installation of the various traffic calming measures and 20mph zones in the Ward a number of residents have been asking about the latest comments made in the media about how much pollution is contributed to the atmosphere due to having speed cushions and humps in place. I took this up with the Highways Engineer to ask whether the Council had considered the latest research findings and what their opinion was on this thinking. Set out below is the response I have received from the Highways Engineer:

“Dear Cllr Anderson,

With regards air quality, the Council is aware of recent media pieces on air quality and that the draft NICE guideline on ‘Air Pollution: Outdoor quality and health’ is currently out for consultation and officers within the relevant services are currently reviewing the documents pending providing advice on any response from the city on the proposed guidance. 

In the document there is a section on ‘Smooth Driving and Speed Reduction’ which seeks to provide advice on best practice for the use of traffic calming.  In Leeds traffic calming of various types has been used to very good effect over period of 20 or more years to reduce road casualties on our roads. Our experience over this time where a range of measures have been used is that vertical measures such as speed cushions, humps and tables is the most effective measure for speed reduction compared with horizontal measures such as chicane and priority systems although there is a place for each approach.   

Over the years the design of speed reduction measures has developed and evolved, and the type of measures that NICE are advocating are increasingly being used because they not only help to smooth the journey and speed but are also more comfortable for vehicle passenger, cyclists and motorcyclists.  The designs used in Leeds are based on national best practice as exemplified in Department for Transport regulations, advice and guidelines and the allied research and best practice that underpins them.  Officers already maintain a good knowledge of the latest developments and we will looking at the NICE findings and considering any lessons there are for our future practice here in Leeds. 

Furthermore, thanks to regulation relaxations in recent years, local authorities are able to implement 20mph zones without the need to implement large rafts of vertical traffic calming features. The Department for Transport stipulate that within a 20mph zone, there must be one traffic calming measure, in the sense described in my previous email to you. Furthermore, they stipulate that a driver must not be more than 50 metres away from a ‘feature’. Previously, a ‘feature’ was a traffic calming measure and most usually took the form of a speed cushion or hump. The modern regulations allow a speed repeater sign to be classed a ‘feature’ and subsequently the number of features proposed within this zone is significantly lower than what may have been proposed under the previous regulations and furthermore, the possible air quality impact is also significantly lower.”