Western Railroad Discussion > Help with derail switch

What is the derail switch used for? Thanks.

skinnytree Wrote:
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> What is the derail switch used for? Thanks.

A derail is a "Safeguard". Used to protect from rollouts or runaways. When cars or whole trains in some areas derail protect is placed to "derail" unattended movement. It purposely derails the cars or locomotive, least its supposed to :)

Generally used along sidings of one sort or the other...mostly industrial types...to prevent cars from rolling back out onto a main line and disrupting traffic.

Hump or Buda style flops over the top of the rail. It is "Supposed" to derail a car but sometimes fails to do so. I have seen cars jump right on over and keep going. I have also seen engines go over them as well and seen them shattered with the weight of the engine.

The best is the split point type. It is usually a switch point set into the running rail. The car or engine has no choice but to go on the ground. In extreme situations I have seen both rails used or a switch to no where. On some the signal department will put in a wafer in the flange way so it gets broken and throws the signals red on the main. It also tells the dispatcher that something got into the derail.

Nudge

The Steel Bridge in Portland, Oregon is a double track lift bridge with a "Y" on the north track on the east end. There are five power operated derails here. Both kinds.

If the bridge were in the raised position a runaway could fall on river traffic below. Many times a full lift is not needed and a runaway would take out the lift span. (engine window height??)

They have a time out (10 min?) on them, like signals that have to time out. If they are left in the non-operated position and then put in the derail position the time out goes into effect before a lift can be done. They are left in the derail position most of the time so the bridge can be lifted without the time out coming into effect. An approaching train calls ahead and if no river traffic they can be removed immediately.

jb

In Maintenance of Way, a portable derail is used as protection on other than main tracks. If we're working on a yard track, for example, we could place a derail and red flag on either end of our working limits. If a car gets away and comes down the track, it should derail before it runs somebody over.