Electrification for overruns

[Graham H]

Hope the title makes sense but on a couple of occasions since the partial electrification of the GW lines I have noticed that electric supply continues off the core route in a few places. At Southcote junction the Basingstoke line has masts (and wire ??) for a short distance. After Westerleigh Junction the line down to Yate seems to have a considerable length masted up but as it was dark I dont know if its wired. I assume its to avoid overruns due to wrong route set but I would have hoped drivers would challenge a route ? Perhaps in some places its to allow an overlap between electric and diesel working to give sufficient time to switch modes but I am not sure even that would be a reason for the two examples.

 

[Magicake]

I don't know about the specific locations you mention but typically at junctions it is provided for a short distance for overrun protection in case of wrong route as you hypothesise. The driver maybe should challenge the route but it makes things a lot easier if there is some mistake.

 

[oglord]

And of course makes extensions easier without having to rewire complex junctions.

 

[najaB]

I assume its to avoid overruns due to wrong route set but I would have hoped drivers would challenge a route ?

They should challenge the route, but the cost of providing a couple of extra masts and a few hundred metres of wiring will be worth it when a driver is able to (sheepishly) reverse back onto the electrified route, rather than having to call out a thunderbird and all the delay that'll incur.

 

[stuu]

Hope the title makes sense but on a couple of occasions since the partial electrification of the GW lines I have noticed that electric supply continues off the core route in a few places. At Southcote junction the Basingstoke line has masts (and wire ??) for a short distance. After Westerleigh Junction the line down to Yate seems to have a considerable length masted up but as it was dark I dont know if its wired. I assume its to avoid overruns due to wrong route set but I would have hoped drivers would challenge a route ? Perhaps in some places its to allow an overlap between electric and diesel working to give sufficient time to switch modes but I am not sure even that would be a reason for the two examples.

The route towards Yate is wired for much longer than normal. It's about 1km which I would assume is a lot longer than the stopping distance of a misrouted electric train, given the junction has a 40mph limit

 

[Jamiescott1]

Theres a few 100m onto the marlow branch line off maidenhead too

 

[Graham H]

The route towards Yate is wired for much longer than normal. It's about 1km which I would assume is a lot longer than the stopping distance of a misrouted electric train, given the junction has a 40mph limit

Yes it was Yate that made me curious as it is a very lengthy overrun and as far as I could tell is wired for the line from Yate TO the junction as well but that might just be because its easier to do the whole lot and not just the line potentially subject to an overrun although I seem to recall the lines are bidirectional in the area anway.

 

[Beebman]

I remember going to Blackpool along the WCML in September 1971 and at Weaver Junction I was surprised to see the OHLE continuing along our route towards Warrington (this was before much of the work had been started on the electrification north to Glasgow). It stopped after about half a mile but my curiosity at the time is something I can still remember today! I think I soon realised that it was an overrun for any wrongly-routed trains but in more recent times I discovered that it was also connected to a feeder station at Dutton just to the south of the A533 overbridge (these days there's a neutral section there and a changeover from Mk.1 to Mk.3a type OHLE).

 

[Snow1964]

Yes it was Yate that made me curious as it is a very lengthy overrun and as far as I could tell is wired for the line from Yate TO the junction as well but that might just be because its easier to do the whole lot and not just the line potentially subject to an overrun although I seem to recall the lines are bidirectional in the area anway.

You are correct about Yate, but the line is on an embankment, with the wires ending just beyond the multi-span Nibley Road bridge. Realistically don’t want to put the large masts with weights/tensioners on a bridge so that might have influenced adding couple of hundred meters

Although rare (on new installations) now due to less electric locos, some overruns allowed loco changes (eg towards Kenilworth at Coventry), cross country trains regularly changed from electric locos there until mid 1980s. So one track is electrified beyond the trailing crossover so loco could pull forward and clear, whilst diesel loco came from another track

 

[GRALISTAIR]

And of course makes extensions easier without having to rewire complex junctions.

Fylde Junction at Preston was wired in 1973. Finally got wired to Blackpool in 2018.

 

[Graham H]

You are correct about Yate, but the line is on an embankment, with the wires ending just beyond the multi-span Nibley Road bridge. Realistically don’t want to put the large masts with weights/tensioners on a bridge so that might have influenced adding couple of hundred meters

Although rare (on new installations) now due to less electric locos, some overruns allowed loco changes (eg towards Kenilworth at Coventry), cross country trains regularly changed from electric locos there until mid 1980s. So one track is electrified beyond the trailing crossover so loco could pull forward and clear, whilst diesel loco came from another track

Yes I remember the change from diesel to electric (or vice versa) taking place there on cross country services. Saved blocking Coventry station while such a switch took place although I do recall a few occasions where the southbound switch did occur in the platform.

 

[Accura]

I had always wondered why the Farington Curve (northbound from the WCML to the East Lancs Line) was wired, however what has been said here makes sense. The curve is electrified for about 1km, all the way to the point where it joins the East Lancashire line, ending at a small siding that can be seen below:

(view looking eastbound from Watkin Lane bridge, just before the curve joins the East Lancashire route)

Oddly the junction from the north of the WCML onto this route (which includes the Ormskirk route) doesn't seem to have any overrun at all, despite seeing far more regular use.

 

[swt_passenger]

I suppose on some of the more recent schemes, if the wiring was ever expected to continue further in a later phase, you’d probably fit a normal tension length, (however long that happens to be), otherwise you’d have anchor portals that would end up in the wrong place?

 

[GRALISTAIR]

I suppose on some of the more recent schemes, if the wiring was ever expected to continue further in a later phase, you’d probably fit a normal tension length, (however long that happens to be), otherwise you’d have anchor portals that would end up in the wrong place?

Certainly there has been anticipation there would be a rolling electrification programme with TDNS etc. Therefore doing a tension length at junctions makes sense to avoid some disruption at a later date.

 

[ac6000cw]

Another reason sometimes for wiring short distances along branches is for shunting & reversing purposes so that a train doesn't block a mainline platform during reversals. Even if it's not used in normal running it might be needed during disruption.

The 1960s electrifications tended to have more of these short extensions, to cater for traction changes on freights (for flows that are probably long gone now) amongst other things. And of course there were all the miles of sidings electrified at places like Crewe which have probably barely seen a pantograph.

 

[zwk500]

I had always wondered why the Farington Curve (northbound from the WCML to the East Lancs Line) was wired, however what has been said here makes sense. The curve is electrified for about 1km, all the way to the point where it joins the East Lancashire line, ending at a small siding that can be seen below:

(view looking eastbound from Watkin Lane bridge, just before the curve joins the East Lancashire route)

I believe this route was wired to allow the Sleepers to change locos when diverted over the S&C, avoiding the reversal at Preston that would otherwise have been necessary. Hence there being 2 sidings at each end.

Oddly the junction from the north of the WCML onto this route (which includes the Ormskirk route) doesn't seem to have any overrun at all, despite seeing far more regular use.

When the line was electrified presumably the only electric services would have been the main WCML expresses, so I guess it was thought the risk of wrong-routing was low enough, and chance of electrifying the East Lancs Line similarly low enough, that it wasn't worth the overruns.

 

[ac6000cw]

I believe this route was wired to allow the Sleepers to change locos when diverted over the S&C, avoiding the reversal at Preston that would otherwise have been necessary. Hence there being 2 sidings at each end.

...and for freight traction changes I assume - as far as I remember, after the early 1970's electrification, only fully (brake) fitted freights were allowed on the northern WCML (most or all of the catch points were removed), so partially-fitted freights had to run via the S&C.

 

[Beebman]

...and for freight traction changes I assume - as far as I remember, after the early 1970's electrification, only fully (brake) fitted freights were allowed on the northern WCML (most or all of the catch points were removed), so partially-fitted freights had to run via the S&C.

I've been on 2 or 3 charters involving steam over the S&C which changed here from electric traction although they were all in the late 80s and early 90s.

 

[rower40]

The ECML spur from Doncaster to Leeds has an Overrun all the way to Neville Hill Depot...

 

[ANDREW_D_WEBB]

The wires extend a short distance along the branch to Windsor and Eton Central

 

[SouthEastBuses]

Another example:

The first 1 km or so of the Welsh Marches Line out of Newport is electrified as part of the SWML overrun.

Additionally, the first 1 km or so of the Wolverhampton-Shrewsbury line is also electrified.

 

[43096]

Additionally, the first 1 km or so of the Wolverhampton-Shrewsbury line is also electrified.

Are you referring to that as beyond Oxley depot?

 

[ac6000cw]

Additionally, the first 1 km or so of the Wolverhampton-Shrewsbury line is also electrified.

That's not an overrun though - it's so electric trains can access Oxley depot. It was added in the early 1970s, a few years after the main WCML electrification in the West Midlands area went 'live'.

 

[SouthEastBuses]

That's not an overrun though - it's so electric trains can access Oxley depot. It was added in the early 1970s, a few years after the main WCML electrification in the West Midlands area went 'live'.

Ahh this makes sense now. And I like the idea of electrifying 400-500m of each line as an overrun, makes it easier to electrify said line in the future should it want to happen, as it avoids having to completely remodel the electrification system at the railway junction (therefore saving costs!)

 

[brad465]

In third rail land you see an overrun at Worting junction, where the down running line for the West of England route has third rail for a short section.

 

[snowball]

Another example:

The first 1 km or so of the Welsh Marches Line out of Newport is electrified as part of the SWML overrun.

If Google Maps satellite view is up to date it's much less than 1km - more like 200 or 300m, stopping before the bridge over Turner Street.

 

[Beebman]

That's not an overrun though - it's so electric trains can access Oxley depot. It was added in the early 1970s, a few years after the main WCML electrification in the West Midlands area went 'live'.

There was a short overrun (including catenary wire) on the Shrewsbury line when the OHLE was first installed in the 1960s and then it was extended to Oxley around 1972 using simple 'tram wire'. 50 years later it's still possible to spot the point of transition between the two types of electrification just after branching off at Wolverhampton North Jct. A short section of the Oxley Chord was (and AFAIK still is) electrified at that time from Stafford Road Jct, presumably in case of misroutings of trains leaving Oxley Depot.

 

[AM9]

Assuming that any overrun was well away from any overbridges etc., would it be viable to raise the conductor above the limit set for pantographs thereby forcing a retraction before the wire deviates deviates to a tensioner/anchor?

 

[norbitonflyer]

Are the overruns energised? If not, it would allow a wrong-routed train to come to a halt without damaging the pantograph.

 

[najaB]

Are the overruns energised? If not, it would allow a wrong-routed train to come to a halt without damaging the pantograph.

I believe they are, since if they weren't an electric locomotive wouldn't be able to reverse back onto the correct route.