Just went and did some quick reconnaissance...
There is indeed a small sidewalk on the north side of the bridge. There's a temporary walkway that's built on the OUTSIDE part of the bridge - simply fenced in with some wire. It dumps out on the reservoir side where several lanes of traffic merge together. Pedestrians just have to be watchful and careful as cars are moving pretty quickly in both lanes.
fendertweed: Let your wife know that when she comes down the hill on Third Ave towards the Winter St/Totten Pond intersection, she'll have to cross the street to the far side of the intersection before turning left to head over the bridge.