The utilities situation under the road is bad (e.g. DNO HV cables in the "Do not disturb" state) but everything is well documented and there is a realistic plan.Lets hope they dont encounter the same issues that has bedeviled the Oxford bridge lowering to accommodation double deck buses.
Unlike Oxford, the Luftwaffe dug up the road in 1940s resulting in some of the more southerly bridge decks needing to be replaced after they were lifted in the air and bent on landing and all the utilities under the road needing to be replaced.