Hi Peter, thanks for your post!
Sorry to hear about your navigation issue, due to the missing walkway. Map Creator is the right tool to report these map errors to us, whereby it is now editable by yourself for many features, including geometry.
Sign into Map Creator. Then, you can add in a ‘Trail’ by clicking on the ‘Add Road’ button in the editing menu found on the right hand side. As soon as that is selected you can start at the point where the trail begins and continue to draw the geometry as it is to reality, with the aerial imagery to guide and help you too. Once you have finished your trial and connected it to the other side of the Humber Bridge, there will be a pop up asking if this is an overpass, underpass or simply connects to the road. You can select overpass here. I attach a screenshot. You can then also add a name to trail if there is one in reality. Otherwise, most of the time, our trials are unnamed.
Hope this helps, and don’t hesitate to post some more queries or questions on this topic!