--- In Ry-ops-industrialSIG@yahoogroups.com, "Kenneth Leaver Jr" <kleaver@...>
wrote:

Your time frame is a huge chunk of history with many changes in the period.

The vast majority of crossings in this era were protected by nothing more than
the basic X-shaped crossbuck, especially in a rural area. Manned crossings were
usually found in the biggest cities, where there was considerable highway and
train traffic, or where visibility for drivers or train crews was impaired.
Electronic devices, such as the "Magnetic Flagman" appeared in the 1920s, but
still required an operator to activate them; this was later updated with
detection circuits and relays to eliminate the expense of the crossing watchman.

The actual wording, placement, colors, sizes and shapes of signs were sometimes
– but not always – specified by one of three area authorities: the State Highway
Commissioner, the County Highway Commissioner or local authorities. As a result,
they differ widely from state-to-state. Where there were no formal guidelines,
the railroad would pick a standard and specify how it was to be used.

Typically, the roads started as dirt trails and were in use long before
railroads came.
For the most part, you'll find that grade separations began in the 1920s as
vehicle traffic levels soared in many cities. What had been bad in the 20s grew
worse in the 30s and many were then completed as Public Works projects.

Period photos from your area and timeframe may help identify what was being
used. Another source may be railroad standards books for the lines that serve
the area you're interested in. Maintenance Cyclopedias usually have general
guidelines for installation and show different types of crossing signals.

In HO, American Limited has a kit (and a static) version of the over-the-highway
wigwag signals – I recall some of these in use into the late 1980s. NJ
International, Tomar, Busch, and many others offer modern flashers and gates,
but be aware the detection and motorizing is usually left up to you.

Lance Burton