What’s the deal with the vestigial El platform next to the express tracks at Wilson?
Wilson was once a stop on the Evanston Express (now Purple Express) trains, and was also a stop for the (now terminated) North Shore interurban trains. Therefore:
Red Line trains (though they weren’t called that then) used the present platform,
Northbound Evanston and North Shore trains used the shorter abandoned platform, and
Southbound Evanston and North Shore trains used the platform along that single track on concrete pillars that veers off the mainline south of Lawrence station, goes through the middle of the Truman College parking lot, and rejoins the main south of Wilson station.
All North Shore service ended in 1963. I don’t remember when they changed the stops on the Evanston Express to bypass Wilson.