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Sharnbrook tunnel

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3 Apr 2011
As far as I know, before MML electrification there were about 3 or 4 passenger trains on weekdays which called at Wellingborough Platform 3 which meant that they would use the Sharnbrook tunnel (or had gone through it northbound).

I believe the tunnel is now electrified and the track doubled, as well as a new platform 4 at Wellingborough. On RTT many of the new Corby-STP services are booked for Platform 4. Does this mean they will go through the tunnel? If not, how can I find out whether any trains will use it?
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RailUK Forums


30 Jun 2009
As part of the re-quadrification, there is a new ladder going in at Wellingborough South Jn, about half a mile south of Wellingborough station, with right-handed crossovers Up Slow to Down Slow, and Down Slow to Up Fast - thus enabling trains to depart platform 4 and gain the Up Fast, thus avoiding Sharnbrook Tunnel. That said, since there is no access from Down Fast any platform except platform 1, it is still the case that anything calling in platform 3 northbound must have come through Sharnbrook Tunnel in the down direction.

Looking at the May 2021 timetable, the only things I can see booked in 3 are freights:

The up Corby-St Pancras services are generally booked in 4, as you say, but looking at such schedules for the new timetable, e.g.:
The line code "UFL" at Wellingborough South Jn indicates the train is planned to cross Up Slow to Up Fast there, so no use of Sharnbrook Tunnel there.

However, there are a few trains that do use Sharnbrook Tunnel - the way to tell is to look for line code "DSL" or "USL" - you may have to look back as line codes are only declared (at least on the MML) where the line changes.

For example, the first train of the morning, 1H00 0432 Corby-St Pancras:
declares line code "USL" at Kettering North Jn, and then no further line codes until Bedford, indicating it is booked to use the Up Slow Line through Sharnbrook Tunnel (and corroborated by the fact it's booked 19½ minutes from Wellingborough to Bedford, rather than the usual 11½, with no allowances beyond the usual [1] engineering time).

On Monday mornings, the first train from Derby, 1B01 0356 Derby-St Pancras:
is again booked over the Up Slow from Kettering North Jn to Bedford North Jn.
Interestingly the schedule for 1B01 for Tues-Fri has enough pathing time in it to give the same arrival time at St Pancras:

I haven't seen any others booked to use Sharnbrook Tunnel - do let us know if you spot any more!
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