I think that other rendering is from an earlier plan. Initially, they were going to demolish the original south span after they built the new north span, and then build a new south span. Then in 2019, they decided to rehabilitate the existing bridge to preserve its heritage features. Rehabilitation of the existing bridge also meant they could adapt the existing maintenance walkway as a pedestrian crossing, so there wasn't a need to build a pedestrian crossing on the northside. The current plan is for the multi-use trail to run on the north side of the highway on either side of the river, and then new ramps will carry the path up under the new north span to the maintenance walkway under the south span.
(EDIT: Whenever you photograph the bridge next (excellent photos btw), you could see if they've started to add permanent fencing to the walkway. In your October photos, it looks like it still only had temporary wooden fencing.)