I notice from old photographs (1960 and earlier) that railway crossing arms are raised to a 45 degree angle when in the “up” position. Modern arms are generally raised so that they’re 90 degrees…pointing straight up…when not in use. Why the change? I don’t think its a clearance issue as even at 45 degrees the arms still appear to leave plenty of room for even the tallest of vehicles to clear…Maybe having the arms extending over the roadway when not in use posed a danger. Was there an accident or event that brought about this change?
Wind.
You’ll notice that in many cases, there are now “fingers” to keep the arms from flopping in the wind.
Odds are those old arms were wood, as well. Nowadays they are rectangular fiberglas tubes - a little more flexible.
Thanks… I looked at some more photos this afternoon and noticed that in the old days the arms were much longer…twice as long as today’ s arms…in order to extend across the entire roadway, not just the oncoming traffic lane. One of these long arms was placed on each side of the track to block all traffic. Unlike the shorter arms of today, it would have been impossible to go around the old arms. Maybe raising such long arms to vertical would have presented problems of its own as you noted due to wind.
Another factor is that sometimes the gate arms were operated manually, and a similar mechanism might be used in earlier motorized versions. Many busy grade crossings were actually manned, some surviving even into the 1970s and 1980s before getting automated.
Excellent… I never thought of that. Raising a big old arm to straight up would have required alot more effort when 45 degrees would have sufficed. Also lowering from just 45 degrees would have resulted in getting the arm down and into position quicker…
The arms are counter-balanced, so bringing it up or down shouldn’t be really any great effort.
Starting that electric motor from rest takes a little more torque effort if not vertical or all the way down. Shortens motor life.
I was under the impression that as a fail-safe, the motor actually keeps the arm up. If the power goes out, gravity causes the arm to drop… I could be wrong.
Of course, the counterweight does contribute.
With the current type of gates; different with the older type that I was told about by the old heads. The older type were the last ones to go on the branches where I worked in CO KS OK and NM. The branches were also the places where the clearance argument above got blown-up by agri-dummies with combines, harvesters, folding discs and haywagons. Even the more modern gate systems get attacked by that overly tall and overly wide stuff today along with crossbucks that have the misfortune to get in their way.
The arm when up is held by a brake (latch) that releases upon the track logic calling for the arm to lower or a loss of power, The motor acts as a dynamic brake to control the descent of the arm. If the logic is that the arm should rise, the motor will operate to bring it up to the latch position. Many have seen cases where the arm doesn’t rise all the way up and latch, starts to fall and then rises again only to fall again and repeats this. Something is out of adjustment.
Ulrich, please allow me to differ with you on one point. Having driven commercial vehicles for over 30 years, I can tell you that vehicles are allowed to be up to 13’ 6" tall. If I drove a tractor-trailer past a gate raised only 45 degrees, the gate would have to be installed some distance from the roadway to allow clearance. Of course, trailers weren’t that tall decades ago. But did you happened to see in those old photographs if the gates were some distance away? I can remember seeing some gates raised only to 45 degrees, but I don’t remember how close they were to the roadbed.
Some historical perspective:
https://clevelandmemory.contentdm.oclc.org/digital/collection/nickel/id/145
http://www.whippanyrailwaymuseum.net/exhibits/structures/railroad-crossing-gates-a-signals
They aren’t 45 degrees, but they aren’t vertical, either.
Thanks for the links. One fo those hand-cranked models and gatekeeper’s shanty reminds me of the Broad St. crossing in downtown Tamaqua, Pa. My cousing and I used to pass through there many times back in the fifties. I’m hoping this summer I can get some pictures of 2102 stopping at the station.
Good points and comments. An old photo of a crossing in my home town inspired this post… the arms looked about 45 degrees when not in use, but the photo was from the 1930s, so likely no vehicles were tall enough at that time to cause a problem. Probably taller vehicles and alot more of them with each passing year brought about the change to full vertical when not in use.
One added benefit of not having them raised to vertical… with the striped arms hanging over the roadway they’re more visible to oncoming traffic… at least drivers know there’s a crossing coming. With the arms fully vertical they’re not as visible to drivers who aren’t paying as much attention to what’s to the left and right of them.
On the manually protected grade crossings with which I’m most familar, the gates were generally raised to about 60 to 75 degrees above horizontal. Not quite vertical but close enough to reduce clearance issues with semis. This applied to both motor-operated and pneumatically operated gates.