Passing Loop Clearance

[TheSignalEngineer]

I don't think the existence of the middle six foot space which was usually referred to as the ten foot even though it was only six feet wide was a problem on the WCML until modern safety rules came in. Up until then we just worked up to the sleeper ends of the open road protected by a 20MPH speed restriction and the old rule T4.  A bigger problem was perhaps that the widening was done on the cheap, with the amount of extra land required being reduced by steepening the bank sides, this made slips more likely.

I can remember covering jobs on the middle roads between Euston and Roade with the adjacent lines open for traffic. That included work like laying in a complete new crossover. Prior to starting with BR I remember seeing plentry of overhead wiring work going on with trains running alongside. Before T4 and protective TSRs the notice submission would just say something like "Up Fast & Down Slow Blocked. Down Fast & Up Slow Blocked between trains, pass booked services".

[Guy Rixon]

I've read that the SER built its double track to a narrower spacing than the standard 6' between rails and therefore no coaches wider than 8'6" overall could be accepted on that railway. Clearly, this had been sorted out by the time that BR Mk1 stock took over (Hastings line and narrow tunnels excepted, of course). Can anybody comment on the truth of this story and on when they realigned the main lines?

[Trog]

I can remember covering jobs on the middle roads between Euston and Roade with the adjacent lines open for traffic. That included work like laying in a complete new crossover. Prior to starting with BR I remember seeing plentry of overhead wiring work going on with trains running alongside. Before T4 and protective TSRs the notice submission would just say something like "Up Fast & Down Slow Blocked. Down Fast & Up Slow Blocked between trains, pass booked services".

 

As recently as the 1980's we were re-railing CWR on the middle roads, during midweek day time blocks with the trains running at line speed on both sides of us. The welders would set up a weld wait for a train to pass, give the moulds a quick once over, and drop the weld pronto, so that the steel had a couple of minutes to solidify before the next train came past.

[The Johnster]

Regarding the 6ft distance.

 

As mentioned above, since many of us use 16.5mm gauge (if modelling in 4mm), it seems to me that often this distance just looks wrong on a model. It often makes the tracks look too far apart - unless you're modelling ex-GW broad gauge lines where distances might be greater.

 

I think a more visual approach is sometimes required, rather than religiously following a specific prototype dimension.

 

Hmmm.  Accepting your point about the 'look' of model 6' between tracks,  if you bring the tracks in towards each other you will have to be very careful of clearances.  8'6" wide stock projects outwards beyond the outer surface of the rails, that is by a scale 2'3" on 00 track.  Similar stock on the adjacent road will also do this, so only a scale 18" of clearance is left.  This will be used up very rapidly as soon as the least curvature is involved, and if you are running at reasonable speeds the vehicles will rock a bit, so if you will in trouble if you do not keep a close eye on things...

 

GWR Centenary stock is a scale 9' wide...

[Pacific231G]

Could you support that statement? My experience of UK practice is that 6ft is very much the most common spacing for double tracks, and for the pairs where there are multiple tracks.

Clearly HS1 is an exception as it has to take European size trains, but even then I don't think its as much as 10ft.

Regards

Google Earth is your friend here at least for current practice. Since you know the gauge to be 1435mm that gives you a "ruler" for measuring everything else from the lengths of points and crossing angles. In some areas where the aerial photos are particularly clear you can even measure the sleeper spacing and point timbering. 

[DCB]

I have tracks down to around 43mm spacing, it comes down to whether the trains actually clear each other as to what clearance to provide.   Modern locos have less end throw than the old ones like Triang's M7 or the Hornby tender drive King so tracks can be squeezed down to reduced clearances, I used 50mm on Set track radius curves.    

One big advantage of close track spacing is that points and crossovers are shorter, or you can use a larger radius for the same length.

The lesson I have only recently learned is tracks are paired, a pair with a six foot and then a ten foot, no wonder my evenly spacded through station tracks look wrong.

[TheSignalEngineer]

.........

Similar stock on the adjacent road will also do this, so only a scale 18" of clearance is left.  This will be used up very rapidly as soon as the least curvature is involved, and if you are running at reasonable speeds the vehicles will rock a bit, so if you will in trouble if you do not keep a close eye on things...

The old BR Signalling Principle on track circuit clearance points stated a minimum passing clearance of 18" between trains on adjacent lines.

 

I have tracks down to around 43mm spacing,...............................

The minimum laid down on the old 'Requirements' Blue Book was 11'2" between track centre lines which would be 44.67mm at 4mm scale.