Singling a line

[cyclebytrain]

Reading the thread about Ribblehead being singled and whether or not that produced a better load profile I got to thinking about other formerly double track lines that have been singled and realised that there are some where one line now occupies the middle of the formation, some where either the up or down track was left in place and the other removed and, in some cases where the now single track switches between what was the old up and what was the old down without any obvious reason for why the switch happens where it does.

All this has made me wonder; what's the criteria for deciding how to single a line?

 

[Bletchleyite]

Thinking of one I'm familiar with, Ormskirk to Preston, one reason for moving from side to side is to be able to serve the main platform (the one with the building and road access, even though it's likely the building will be disused) at stations, allowing any footbridge to be removed.

I doubt there are many where it's in the middle on singling, as relaying the whole thing is going to negate the savings. It might however be slewed into the middle if it is later relaid?

 

[big all]

middle off the track formation will require lots off unessisery work
weaving from one bed to the other will often be from newest laid to newest laid or best quality bit off track
often when singling is in the air over a few years they will tend to not renew two parallel tracks just muster through replacing the worst off the two beds but off course not always

 

[Bald Rick]

It usually depended on two main factors:

1) the condition of the relevant track, generally the best will be kept
2) the condition of what is under the track. If the formation / embankment / Bridge is iffy on one side, the track will go the other side. If both sides are iffy, it will go in the middle.

 

[John Webb]

There may also be changes from one side to the other to maximise curve radius, which will allow a faster line speed and/or less wear on wheels and track.

 

[Dr Hoo]

Clearances under arched bridges for electrification or container gauge are a major reason for slewing to the ‘middle’.

 

[Metal_gee_man]

Or use the Skegness branch as an example, double tracked most of the way, and yet trains exclusively use one line up and down only moving off to use opposite platforms, it must minimise costings for maintenance

 

[bunnahabhain]

Or use the Skegness branch as an example, double tracked most of the way, and yet trains exclusively use one line up and down only moving off to use opposite platforms, it must minimise costings for maintenance

Could you explain more? None of the Skegness line has any single facing platforms. Whilst the down line is more predominantly used the track does cross over to the up side in some places, notably at each end of the single line between Hubberts Bridge and Boston. At Sleaford the line is somewhere in the middle of the old four track section between Sleaford East and Sleaford South, I suspect on the old up Skegness track judging by the sharp angle the Jolly Joint chord comes in at the pointwork.

 

[Metal_gee_man]

Could you explain more? None of the Skegness line has any single facing platforms. Whilst the down line is more predominantly used the track does cross over to the up side in some places, notably at each end of the single line between Hubberts Bridge and Boston. At Sleaford the line is somewhere in the middle of the old four track section between Sleaford East and Sleaford South, I suspect on the old up Skegness track judging by the sharp angle the Jolly Joint chord comes in at the pointwork.

I was probably not supposed to use the words exclusively, for a majority of the journeys single line running is the norm, you can see it when you look at the railheads one that obviously gets regular use, and then an oxidised rusty rail that has very little use, I assume scheduling allows this

 

[Tomnick]

I was probably not supposed to use the words exclusively, for a majority of the journeys single line running is the norm, you can see it when you look at the railheads one that obviously gets regular use, and then an oxidised rusty rail that has very little use, I assume scheduling allows this

None of the double line sections are signalled reversibly anywhere on the Skegness branch. Trains always use the left-hand line as normal, unless something’s gone really wrong.