The never varying variable speed limit of the M4 at Newport

It is said that “You never know unless you ask”. So I have pondered over the last few years “Why the hell is west bound section of the M4 past Newport always set to 50Mph?” It makes no sense. Over the last 10 years, the congestion along the M4 in South Wales has been horrific. But it was going to be OK, as it was going to make everything better in the long run.

So after years of work, the section of motorway near Cardiff got an extra lane. The metal centre barrier was replaced with a concrete wall. And Newport got a variable speed limit. I vaguely remember a time back in early 2011 when it was possible to drive past Newport at over 50Mph. But for years, now the west bound section between J25 to J26 has been set to 50Mph. Regardless to time of day or night, weather conditions or temperature, always 50Mph. Whats the point of a variable limit that never changes?

So I asked. I asked Traffic Wales. And I’m surprised I got an answer. So I’ll strip out the three paragraphs of rational and get to the actual answer.


Q: Why is there a section of the west bound M4 variable speed limit section that never varies?

A: On the Westbound Carriageway, following the Brynglas Tunnel Fire in 2011, reduced lighting has been in operation which requires the permanent display of a 50MPH speed limit being applied on the approach and travel through the tunnel. Welsh Government are seeking to provide a more permanent solution through provision of new lighting in the westbound bore of the tunnel. Such a solution will have a significant impact on the road network during works to install these and must therefore be carefully scoped and planned prior to any works taking place.


So what ever you do, please don’t tell the Welsh that when the sun goes down it gets dark. Otherwise they have a nation wide 50Mph maximum speed restriction in place.