Mr. Tops wrote:That's a gate at an interlocking.
Not to get nit picky, if its not tied into a signal system on the other road, its not an 'interlocking' then. You're right that it is a 'gated crossing'. Interlockings mean you can't have conflicting routes at the same time, the 'protection' was interlocked to prevent such a thing. Either mechanically or electrically. In this case, its unsignalled, thus a non-interlocked crossing. If you're a student of railroad history or railroad technology, I highly recommend seeing how the old mechanical interlocking beds work. Truely, the computers of the late 19th and early 20th centuries and 'space age' technology.
However, a lot of the time, those gates *would* be tied into the intersecting line's signals. While not a true 'interlocking' in the traditional sense, they would at least drop the signals to restricted proceed on either side of them while the gate was 'open'. An example of this was the CNW's KD line crossing the MILW Williams Bay line in Northern Illinois. Tower was removed, absolute signals removed, and a gate was installed on the CNW that was tied into the MILW ABS signals. When the CNW crossed, they'd check for cross traffic, 'open' the gate (dropping the signals on the MILW), wait the prescribed time, then proceed. If a train showed up on the MILW during the prescribed time, they closed the gate and waited for it to pass. This carries on in the current era with the 'wait time' before occupying the main at a switch that isn't controlled by the dispatcher. Check for traffic, open up, wait the allotted time, then occupy the main.
In the case of unsignaled lines, both roads would have to come up to the location prepared to stop but in this case C&O/CSX would be able to continue on without stopping if the gate was not set against their movement.
In a more modern example, Brighton Park was another example of a non-interlocked crossing. All trains approached and stopped, and the signals by the switch tenders shack would then indicate which route had authority to proceed. I don't know if the blades were interlocked to keep from allowing a move on the Alton to coincide with a signal being lined for either the PRR, CJ, or B&OCT. I don't *think* they were (could definitely be wrong on that), so it was entirely up to the switch tender to keep his/her due diligence. The signals weren't interlocked between the roads on the approaches either, so it was possible to have conflicting movements lined thru Brighton Park at the same time. So, it was possible to get a signal on the B&OCT (et al) into the 'side' of a train at Brighton Park. If you were sitting side by side with another train going the same direction, the switch tender would raise a lantern or give a 'ahead' signal to the train they wanted to proceed.
Practice Safe CSX