The Branch Line Society

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Norfolk Broads Signal Box Visits
Saturday 1st August 2015

21 members met at 09.30 outside Norwich Thorpe station on a hot sunny day. After a safety briefing from host and guide, Local Operations Manager Adrian Webb, the small convoy headed off to the nearby Trowse Swing Bridge. https://goo.gl/6Q5SBf Hidden away, the box is accessed very obscurely through Colman's Factory (NR do have running powers!) and, after being waved though Security (obviously as keen as mustard!), the box was reached via an internal road which does not appear on any maps. There was some discussion on the day about this access road and if it might have been on the course of a previous internal siding. On opening in 1987, this was just a Bridge Box controlling the River Yare swing bridge on the Norwich to London main line. As part of electrification and resignalling, a new single track bridge was constructed. The previous bridge, the same design as Oulton Broad (visited later), was double track and remained in use while the new bridge was constructed and tested alongside. It has an unusual rigid overhead metal AC conductor rail (known as a 'bar conductor'), which we were able to view close up, instead of overhead wires. The bridge is out of use to tall boats and can only be operated manually, a rare event. River traffic is advised that it is unable to be opened by two red flags on the roof of the box (as elsewhere). If a swing bridge is available to 'open' for river traffic, then one red flag is flown. A double track replacement has been suggested for this single track rail bottleneck which causes delays. For the options being considered see (BLN 1221.1708).

Around 1988 the Norwich area 'emergency panel' was moved to Trowse Swing Bridge box when Colchester took over control of the area. This panel was first commissioned on 26 January 1986 (with the area subsequently extended) in a temporary 'Norwich Box', just south of the station on the Up side. If Colchester loses control of the Norwich area, the panel can be switched in and operated under the supervision of a Colchester signaller. It cannot be operated as a 'block post' in its own right as there is no telephone concentrator (railway jargon for a mini-switchboard). Some of the signallers in the box use the panel display to help regulate conflicts at Whitlingham Jn, as they can see if any services are delayed leaving Norwich. The final piece of the jigsaw is the Vaughan Harmon Modular Control System VDU workstation, commissioned in 2000 to control Whitlingham Jn and the Sheringham branch. It works track circuit block to fringe with Brundall and Colchester (Norwich Panel). The signaller sets routes using the entrance/exit principles either by using the tracker ball or the keyboard. As well as supervising a CCTV crossing at Walpole, the box looks after several other Automatic Half Barrier and user worked crossings. There is an old style gong on the wall above the workstation which is the emergency alarm from Colchester. This was tested during our visit with 16 bells – 6 (obstruction danger!). It makes a pleasant change from the screech of the new style alarm from Brundall Box, also tested during the visit, but there would be no mistaking which alarm is which!

After thanking the duty signaller, the group made for the rather isolated Somerleyton station for Somerleyton Swing Bridge over the River Waveney. Prior to making our way to the box, via the authorised walking route, Adrian took a line blockage. This procedure, repeated on returning to the station, was required as a safety measure due to our group size and because the walking route was on or near the running line. The box works absolute block to Reedham Swing Bridge and Oulton Broad North boxes. The 1904 Great Eastern box has a 14 Lever McKenzie & Holland frame and the bridge control equipment. The provision of outer home signals in both directions means the bridge can be swung without the need to 'block (the line) back' to either of the adjacent boxes, unlike at Reedham Swing Bridge. The Down signals (SB7 & SB8) are shown as having detonator placers but these are no longer used as NR is unable to source detonators! In order to avoid delaying trains, the signaller is instructed not to swing the bridge for river traffic after accepting a Down train from Reedham.



The most remote location visited, only accessible by walking along the railway or by boat, note there was a line possession and the bridge is open to river traffic anyway. The single red flag flying indicates to river traffic that it can be opened if required. A double red flag indicates that a bridge cannot be opened, for example unstaffed, stuck or broken down.
[© Andrew Gardiner 2015]

As it was the peak summer season river traffic was busy and the bridge was opened and closed several times during the visit. This allowed members to observe proceedings from the signaller's perspective on the operating floor and from a place of safety behind the box. The basement locking room (which also housed the two electric motors for the bridge) was also visited. To swing the bridge one motor releases the wedges which keep the bridge fixed and at the right level for rail traffic; then it rises about a foot and is finally swung by a cable pulling it. The process is reversed to close it to river traffic.



Instructions (more complicated than might be imagined) for operation were on the wall of the box.
[© Andrew Gardiner 2015]

While the signaller usually keeps an eye out for boats, they can make contact by VHF radio. Wooden advice boards attached to the box have been replaced by a screen-based system controlled from the box using a laptop. These advise river traffic of when the bridge will open and for how long. In addition to controlling the bridge, the box releases a ground frame for a trailing crossover just south of the station. It is electrically released by Lever 5 but is rarely used (mainly during engineering work) and is expected to be removed with resignalling.



During a line possession, the BLS Orange Army returns after a successful invasion of the normally tranquil and remote Somerleyton Swing Bridge box; a ¼-mile northwest of Somerleyton station with no road access. The box and one of its semaphore signals is on the horizon round the curve in the middle of the picture. The bottom of the Lowestoft (Down) P2 north end ramp is at the foot of the picture. A relatively unusual feature nowadays is that passengers have to use the Barrow Crossing shown to reach and exit the Norwich Up direction P1 (left). Despite the station's remoteness it has a train every two hours to Norwich and Lowestoft although services do not stop on Sundays.
[© Andrew Gardiner 2015]

Next was Lowestoft an 1885 Great Eastern box with a 61 Lever Saxby & Farmer Duplex frame installed in 1905. It controls the three platform station, (P2-4 as P1 no longer has track) as well as a relatively extensive, but heavily overgrown, set of sidings and works absolute block to Oulton Broad North. Routing codes are added to the normal 'Is Line Clear' bell code to let the signaller at Oulton Broad North know if the train being offered is for Ipswich or Norwich. While traffic is relatively light, this feature is useful if the schedule is altered.

The box is extremely well kept, with a polite notice on the block shelf asking signallers to always make use of the lever cloths provided. Other interesting features include the foot press electrical releases for points and facing point lock levers, locked by track circuits. The signaller has to press them with his foot when operating these levers. If the respective track circuit is free, then the lever will be released electrically. While they need to be operated for point lever movements in both directions (i.e. normal or reverse), they only need to be used for facing point levers when the points are being unlocked (i.e. it is possible to reverse the lever and lock the points even if the respective track circuit is occupied).

Trains approaching the station are advised of their route by a theatre route indicator on the inner home signal. This will display '2', '3' or '4' for the platforms or 'S' for the Sidings. While the indicator itself is operated electrically, the levers are all mechanical. Prior to operating the lever for the signal itself (lever 57 main arm or 38 calling on arm), the signaller will set the route and then pull the respective route lever (53, 54, 55 or 56). The route is then proved by a combination of mechanical interlocking in the box and mechanical detection outside on the ground. Adrian showed the group the latter feature, which was clearly visible from a place of safety; a sort of Victorian mechanical computer, with numerous wires and rods but safe, effective and had certainly stood the test of time. While the distant signal is now fixed at caution (as it is defective), it was previously worked; relatively unusual for a terminus because buffer stops are considered to be a signal at danger.

Oulton Broad North was then visited. As well as the junction with the East Suffolk line, the box controls the very busy A146 level crossing. Despite signallers doing their best to minimise delays to road traffic, this is a hot topic locally and was challenging to members of our group trying to take external pictures from the other side of the road! This 1908 Great Eastern Box was extended in 1928 when Oulton Broad North Junction Box was abolished. It has a 35 lever McKenzie & Holland frame and works absolute block to Somerleyton Swing Bridge and Lowestoft. The former Radio Electronic Token Block (RETB) working has now been replaced by track circuit block on the East Suffolk line where it continues to work to Saxmundham, aided by a VDU train describer. As there are no slot arrangements in either direction, it is in theory possible to have a 'Mexican standoff' as there are no controls preventing both signallers setting a route onto the East Suffolk single line at the same time! While there is no risk of collision as there are intermediate signals on the single line, the train from Lowestoft would need to reverse if this issue was ever to arise! The Up line from Lowestoft is fully track circuited despite being operated as an absolute block section. This feature allows the Oulton Broad North signaller to send 'train out of section' to Lowestoft even if he has not seen the tail lamp; particularly useful as East Suffolk trains do not pass the box (it is on the Norwich line west of the actual junction). The box also controls Victoria Road Level Crossing by CCTV. Lever 20 electrically releases for Oulton Broad Swing Bridge. Additionally slots are provided on the protecting signals 19 and 21.

After a short walk the group arrived at the penultimate location, Oulton Broad Swing Bridge 'opened' (!) in 1907. It differs from Somerleyton, and Reedham, in that the bridge control cabin is on the Bridge itself rather than in a riverbank signal box. This means the signaller actually 'swings' with the bridge and, in the event of a (rare) failure, would be trapped and need rescuing by boat! It must be quite a nerve wracking experience the first time the signaller operates it unsupervised. A separate signal box is provided; a modern temporary cabin replacing the original signal box that was condemned in 2005.



The previous 1907 vintage Oulton Broad Swing Bridge, the upper section was removed in 2005 as it became unsafe;
the 10 lever frame went for preservation at the 7¼" gauge Barton House Railway, Wroxham.
The lower locking room remains but looks very odd with its flat roof.
[© Angus McDougall]

The bottom of the original box is now an equipment room. As it is now in effect the equivalent of a 'gate box' and not a block post, a release has to be provided by Oulton Broad North (rail traffic permitting) before the bridge can be opened. In addition to this release, the signaller takes back the slot on the two protecting signals using a small panel in the cabin. This then releases a mechanical lever on a small ground frame which unlocks the bridge by withdrawing the bolts. It was demonstrated to the group several times, as a release was taken to protect each group while they visited the bridge control cabin. One group had the pleasure of being 'locked' in the Bridge Control Cabin to allow a train to pass. Of note was the two-cylinder Tangye hydraulic pump to release and reposition the wedges that fix the bridge in position when in its railway operating position, still using water as the medium.

Oulton Broad bridge swings much less frequently than Somerleyton and Reedham; the opening times are co-ordinated with the Harbour Master (in fact they have to be booked 24 hours in advance). During the winter the river is only open to traffic for a few hours daily, although the bridge is staffed as the signaller might need to check the equipment if the train detection fails. Although the East Suffolk line was mostly singled years ago, double track is retained on the bridge (the Down line disconnected) to balance the weight. Entering the Bridge Control room is like stepping back in history into a museum and it is easy to forget that this is an active operational location on a modern railway. This is emphasised by the original LNER operating instructions on the wall which still apply. These also confirm this bridge was the same design as the original Trowse bridge. See https://goo.gl/rV24RT

Final port of call (!) for the day, was Saxmundham box which dates from 1881. In 1986 the East Suffolk line was rationalised and controlled by the RETB system from it. A small individual function switch panel was also provided to control the Sizewell Branch connections. To increase line capacity, the East Suffolk line (which came very close to being a Beeching closure) was re-signalled in 2012. A new passing loop was provided at Beccles, allowing an hourly service which has resulted in 34% passenger growth on the line in 12 months. The line is now controlled from Saxmundham using a miniature electronic system, similar in operation to Trowse Swing Bridge. Track circuit block regulations apply throughout, using axle counters. It fringes with Oulton Broad North and Colchester (Ipswich Panel).

The Sizewell branch is operated under train staff & ticket regulations with a divisible train staff. In addition to the train staff section, there are two segments of it which can be unscrewed known as 'the tickets'. If more than one train needs to run on the branch, in the same direction of travel, the first driver is issued with segment 1 of the staff. He is also shown the main staff (and segment 2) which proves to him that no train can be proceeding in the opposite direction. Stop boards exist at the end of the branch and once the (complete) first train has arrived within the protection of the stop board, the signaller will be advised accordingly. He can then repeat the process using segment 2 for a second train. The last train to proceed in that direction will take the train staff itself (with or without the other two segments attached accordingly). Once the whole train staff is at the end of the branch, trains can then start to return to Saxmundham using the same process. This method of operation is relatively rare, but not unique, on NR. In addition to operating two barrier crossings from the box, the signaller supervises 26 user worked crossings and 23 automated crossings on the main line and two user worked crossings on the Sizewell branch. The automated crossings are a mix of barrier and open crossings, all locally monitored. The signaller will receive several hundred calls per shift, particularly during the harvest, and is therefore kept very busy despite the standard train service being hourly in each direction.

After a most interesting day with superb weather in a lovely area, the group thanked Adrian. In appreciation of the facilities kindly provided, £400 was donated by participants to the Isle of Wight Steam Railway, Adrian's chosen good cause.

For more pictures by Andrew Gardiner see https://goo.gl/e73HZK.