Prototype Railroading: Restricted Speed

Lately, restricted speed has been a pretty common thing along the Forsyth Subdivision.  The reason for this is all the rain, which I talked about a couple of weeks ago.  About two days after my previous post about the rain, there were some serious problems.  Hillsides, which could not take any more water, began to wash away.  In some locations, the side of the hill slid down to the bottom, including plants and trees.  There are now several spots where grass comes right up to one of the rails, and because the slide was so large, it looks like the grass was planted there!  In one particular spot, there is a tree which gets closer to the tracks every day.  Because of all the slides, and because of the size of the slides, there are almost no slide fences left.  There are a couple spots where a few posts are in place, but in many places, the entire slide fence is simply gone.  Slide fences protect the trains from rock falls or slides.  They are wire fences put up along the railroad, between the tracks and a hill.  When a slide occurs, the fence does not stop it, but rather warns of it.  As rocks and mud slide down the hill and hit the fence, it breaks electrical connections in the fence.  With those electrical connections broken, the block signal system puts up red signals, and stops trains before they run into a pile of rocks on the track.  This is very important, because occasionally the rocks weigh as much as a locomotive!

When the slide fences are inoperative, malfunctioning, or, as the case is now, when they are gone, there is nothing to warn trains of a slide.  With all the rain we have gotten over the last few weeks, a slide is a very realistic possibility.  With such a high possibility of a slide and no working warning system, trains must operate at a speed that allows them to stop short of an obstruction on the tracks.  Since the size and weight of trains vary quite a lot, and distance of visibility can vary a bit too, it is impossible to say that all trains must operate at a certain number of miles per hour.  For some trains that number might be too slow, and for others it could be too fast.  That is where restricted speed comes into the picture.

Restricted speed, by definition, is a speed at which the crew can stop the train in one half their range of vision.  This means that trains that can stop faster are allowed to move faster.  Additionally, restricted speed is not to exceed 20 mph.  This allows train crews to make the judgement on how fast they should go.  Restricted speed varies depending on the type of train.  For a very heavy train, with a high tonnage per brake, restricted speed will be lower, simply because it will take longer to stop the train.  For a lighter train, with a fairly low tonnage per brake, restricted speed will be higher, because the train will be able to stop sooner.  Restricted speed also depends on weather conditions.  On a clear day, when visibility is at its best, all trains will be able to operate faster while operating at restricted speed.  This is also true on long, straight sections of track, where the crew can see a lot of track at once.  On a foggy night, trains will be barely moving at all due to extremely low visibility.  Similarly, on a curved track, where the view is blocked just a short distance ahead, trains will move slower, due to reduced visibility of the tracks.

Restricted speed is different from other speed restrictions.  Restricted speed is considered a head end restriction, meaning once the head end of the train, or the leading wheels, are beyond the area requiring restricted speed, the train may resume travel at the maximum authorized speed.  Other speed restrictions, known as rear end restrictions, effect the entire train.  This means that the train may not resume travel at the maximum authorized speed until the last car is out of the area with the restriction.  The reason for this is because speed restrictions are in areas where track conditions are known, but track structure requires a lower speed.  This can be due to a rough surface, improper alignment, or even a curve.  The condition will effect the entire train, and so the entire train must operate at the indicated speed across it.  In areas where restricted speed is required, the track condition is unknown.  Restricted speed is required because there is no way for the crew to know if the track is clear until they can see it.  Once they see that it is clear, they can pick up speed again.  There is no reason for the entire train to go slow once track conditions are known and permit faster movement.

Lately we have been at restricted speed where the slide fences once were.  When they get around to fixing and replacing them, we will be able to operate faster through those areas, because the warning system will be back in place.  Until then, we just have to go slow enough to stop before we encounter any obstructions.