The Sharnbrook Line

[Haywain]

This part of the Midland Main Line is "up hill and down dale", crossing the River Welland at Market Harborough, the River Ise at Kettering, the River Nene at Wellingborough and the River Great Ouse at Bedford,

It actually crosses the Great Ouse seven times between Sharnbrook and just south of Bedford station.

 

[John Webb]

......The goods lines south of Glendon were not constructed for passenger use, and did not have signalling suitable for passenger trains. Remember that in those days moving coal was more lucrative than moving people! The slow lines south of Bedford only got upgraded for passenger use when the DMU service was introduced in 1960. I think that the Wymington tunnel section was only passed for passenger trains after the remodelling and resignalling at Bedford that immediately preceded the BedPan electrification......

The goods lines south of Bedford were slowly extended over the years, the Up Goods taking precedence to get the coal into London. They were signalled by 'Telegraph Bells' rather than the full Absolute Block (AB) system. By 1894 the paired goods lines were continuous from Harlington to just south of Elstree. On the opening of the second Elstree Tunnel in 1895 the goods lines from St Albans South towards London became the Slow Lines and the former Passenger lines became the Fast lines, all worked under AB. (Hence the new St Albans South box built in 1892 in anticipation of the extra signalling needed.) In July 1906 the goods lines from St Albans South to Harpenden Junction, north of Harpenden station, became Slow Lines for passenger train use, the goods lines remaining as such until, as you say, 1960.
It was 1981 that the goods lines from Bedford to Sharnbrook were made into slow lines.

 

[eman_resu]

Here: https://goo.gl/maps/5PPRojHbpp2nFwQN7 (zoom/pan a bit to get your bearings)

With that quite significant deviation between the lines, is any difference between the chainages on the adjacent lines, and how do they deal with that?

 

[pdeaves]

The deviation is 5ch longer and has its own engineers line reference WYM http://www.railwaycodes.org.uk/elrs/_mileages/w/wym.shtm
Some systems ignore the difference, some don’t!

 

[Senex]

The Midland company defined the south end of the Wymington Deviation as Bridge No. 68 at 58m 34ch and the north end as Irchester South signalbox at 62m 8ch via the main lines and 62m 12ch via the goods lines, with the tunnel from 59m miles to 60m 4ch.

 

[Taunton]

Pre-electrification there was a morning peak Up service booked on the route for pathing, but no passenger service is now booked slow line South of Wellingborough South Junction.

I used to look out for this Up service, although I never used it, not that many years ago, when I had a period of being regular on an early morning St Pancras to Derby train, which passed it at various points on the Up Slow line, or at Wellingborough station if it was a bit late. Seemed a bit of a novelty to see its HST running along the parallel alignment. Some days it was missed altogether, which I put down to it being in the tunnel while we were going the other way.

 

[eman_resu]

The deviation is 5ch longer and has its own engineers line reference WYM http://www.railwaycodes.org.uk/elrs/_mileages/w/wym.shtm
Some systems ignore the difference, some don’t!

The Midland company defined the south end of the Wymington Deviation as Bridge No. 68 at 58m 34ch and the north end as Irchester South signalbox at 62m 8ch via the main lines and 62m 12ch via the goods lines, with the tunnel from 59m miles to 60m 4ch.

Thanks everyone who answered.

 

[70014IronDuke]

Where exactly is this so-called 'Sharnbrook Line'? Somewhere between Wellingborough and Bedford on the Midland Main Line?

It isn't known as the 'Sharnbrook Line' - except by the OP. If is usually referred to as the Wymington deviation - I assume that is also the official name. And as it begins north of Sharnbrook Tunnel *, it's a more sensible name (Although there has never been a station at Wymington to the best of my knowledge, and it is a long name!)

*ooops - see @Senex below. I should have written as it only begins truly 'serious' deviation north of Sharnbrook Tunnel.

I think that the Wymington tunnel section was only passed for passenger trains after the remodelling and resignalling at Bedford that immediately preceded the BedPan electrification.

It may have been classified as a goods line - but it was regularly used for diversions in the 60s and 70s - and at short notice too. In the early 70s, the up Thames-Clyde was not infrequently running late, and the 17.10 ex-Derby semi-fast was then typically sent out from Leicester in front of the TC, to be routed onto the slows at Glendon North, whereupon the TC would usually overtake the semi-fast between there and Bedford. The semi-fast would then switch to the fasts to StP. I did this several times in those years.

Is there time in the Corbys to reopen the old Irchester station? It'd presumably require either new crossovers or a general linespeed lift of the slows to make it work, which is a shame because Irchester and Rushden together would probably contribute a fair amount of London and Wellingborough/Kettering traffic...

In an ideal world, the Corbies should split at Bedford, with the front half going forward fast (as now) and a back half going slow lines and stopping at Bedford North Parkway/Milton EArnest (or whatever you want to call it) and Rushden before reversal at Wellingboro. I say in an ideal world in case anyone thinks this is speculation - but I didn't start it in any case

The Midland company defined the south end of the Wymington Deviation as Bridge No. 68 at 58m 34ch and the north end as Irchester South signalbox at 62m 8ch via the main lines and 62m 12ch via the goods lines, with the tunnel from 59m miles to 60m 4ch.

Hmmm. So the fact that the goods/slows drift a few yards eastwards from the fasts south of the tunnel mouth makes that section also part of the 'deviation'. Interesting - and technically true, I suppose.

EDIT: it’s also still known as the MML slow lines, despite being a fair way from the fasts, and a couple of hundred feet(?) below!

IT is surely not as much as that - maybe 60 feet? - perhaps a bit more in the tunnel itself right at Sharnbrook Summit on the fasts - but nothing like 'a couple of hundred'.