I HAVE driven the SDR from its opening and generally find it a great M4 alternative.

I do feel that the designers missed an opportunity to make it a viable alternative by having most of the roundabouts with tight entrances that reduce speed through the whole roundabout.

A little alteration (gentler entrances or hamburger junctions) would fix this.

Also a method of closing the SDR to local traffic would also allow it to be used an emergency M4 bypass for occasions when the tunnels are closed.

You forgot to add December 21, 2010 to your timeline (the date when the risk of falling ice closed the tunnels).

Paul Smith,
Rogerstone