The line from Smalley Street to Curtis Street (the entire layout) received new automatic gates flashing lights in Summer 1952. The Employee Timetables note where they are in use, and in April of 1952 only East St. and Wooster St. had them (and had since before 1946), but by October '52 the entire line does.
In the photos I posted for the Main St. crossing shanty, there is no signal box in the Cochrane video, but in the later photos one has been added. Presumably for the crossing gates.
But what's interesting is that the Elm St. and Main St. installations aren't your typical crossing gates. In this shot looking south on Elm St in 1956, the manual gates are still present, and what looks like the base of a typical automatic crossing gate. There are no flashing lights, although there is a stop light in this location.
Here is a look at a similar base on the northwest corner of Main St. There wouldn't be a gate on this side of the road (although it could certainly block the sidewalk).
Comparing the one at Main St. to the one at Elm St. there's a difference in the height of the post, with something attached to the Elm St. one.
Note that on the west side of Elm St., the manual gate is still present without any additional hardware.
Looking north, we can see the stoplight and the manual gate on the far side of the yard:
Clearly this isn't a standard installation.
As interesting as all this is, based on the 1955 Thomas Airviews aerial photos, the gates throughout my era remain the same. The gates on High and Washington St. in this photo are the old manual gates, and there aren't any flashing lights installed at these locations either. This is consistent at all streets in this series of photos.
So, despite the employee timetable, my assumption is that the crossings will retain the manual style gates through my entire modeling era. The gates will need to be "automatic." I need to be able to turn off the gates for manual operation in the earlier era, as the Employee Timetables note when the crews must stop and protect while the attendants are on lunch break.
How to build them? I have a couple of the Walthers ones to see if I can easily modify those to make them a little better. They just seem a bit chunky to me, but they are operational and easy enough to get.