Old "ONE LANE BRIDGE" with centerline, and odd square sign style in Texas

[Brian556]

This is in Burkett, TX. There are many interesting things here. The most odd thing is that the bridge has a center line (the old black type), but is also signed as a "ONE LANE BRIDGE". The "ONE LANE BRIDGE" sign is a white square, instead of the usual yellow diamond. Has anybody ever seen this style specified in an old MUTCD? Because I really don't think it was. I'm also wondering who installed it. This looks like an old state highway, but because the sign appears to be off-spec, even for back then, it makes me wonder.

Also note the old bridge supports nearby.

https://maps.google.com/?ll=31.995957,-99.228677&spn=0.000018,0.012456&t=h&z=17&layer=c&cbll=31.99599,-99.228769&panoid=SpMxFp2J5UOI8wh08qUwIQ&cbp=12,290.44,,0,0

[jakeroot]

Interesting find. I think the Burkett Thru Truss Bridge was built prior to the first MUTCD specifications in 1935, though I can't find an exact date. But what specified that white square is still a mystery to me. Still searching...