A hybrid precast and in situ concrete solution was used to construct a tunnel beneath an existing route, incorporating temporary road diversion works and bridge installation. The works required careful sequencing and coordination to maintain access while delivering a robust infrastructure solution. This modular solution in precast concrete, pre-clad, in natural stone was installed without disruption to the very busy NC500 route. The structure was backfilled and the road relayed on top whilst works continue internally to hang a steel walkway for guests to move between buildings on either side of the main carriageway safely. Adding to the complications was the water course that now passes through the tunnel below the walkway gantry.