Thanks for that info. I've only ever been in the car for the journey to/from Le Havre so I didn't know what bike routes where do-able. It just looked grim from my window!There's no problem with the route to and from the Le Harve ferry port and the bridge. The roads are very wide and there's cycle path for much of it. You can even cycle along a massive commercial quayside that doesn't seemed to be used anymore.
@Dogtrousers the bridge I'm thinking of is much smaller than that, on the Caen peripherique. Google informs me it's the Viaduct de Calix....