I got through and round Rouen on Thursday evening pretty easy.
Had a little detour of 20 km before connecting on the A13 direction Le Mans and crossing the Seine at Tourville-la-riviere.
On google maps, it looks like this :
http://goo.gl/maps/l3vLfOn the A28, drive into Rouen up to the E402/N28 where it's closed to cross the bridge (point B).
Take the exit right of the tunnel, at the crosslights go immediately left, 500 meter further, take the exit right onto the D6015.
Always go straight ahead : D6015 > D7 > A13 (you'll see directions to Belbeuf > Tourville-la-rivière > A13)
At Tourville-la-rivière get on to the A13 direction Le Mans.
Detour of 20 minutes, so not too long. This was round 21h on Thursday night with no too much traffic. Don't know how it will be in rush hour, but this could be a route that's not too crowded, only the last part driving into Rouen might be packed with traffic then.