Funded by the Strategic Freight Network, with a contribution from Hutchinson Ports UK (HP-UK), a £60.4 million investment to create a new 1.4km loop on the Felixstowe branch line in Suffolk was successfully brought into service on 29 May 2019, on time and on budget. It facilitates an increase from 33 to 47 freight train paths a day in each direction on this key artery, carrying the highest freight tonnage in the country and serving the largest container port in the UK.
With each train taking the equivalent of up to 76 lorries off the roads, the strategically important Felixstowe to Nuneaton Freight Corridor (F2N) has seen considerable investment in recent years. This has included gauge clearance for W10 ‘High Gauge’ containers and capacity improvement including the Ipswich Bacon Factory Chord (issue115, May 2014), Ely Freight loops, and Nuneaton north chord.
As built in 1875, the 12-mile branch was single track with a passing place at Orwell, roughly mid-way. In 1891, two more passing loops were added, at Derby Road and Trimley. The original loop at Orwell closed with the station in 1959, leaving an eight-mile single-track section. In 1999, the passing loop at Derby Road was extended to accommodate container trains and the whole line was resignalled and controlled from Colchester Power Signal Box (PSB).
The Trimley loop scheme
Following on from a 2005 GRIP 4 (single option development) study undertaken by HP-UK for doubling the branch between Orwell and Trimley for 4.5 miles, subsequent extensive option development work concluded that a 1.4 km loop at Trimley with bi-directional signalling at Derby Road would facilitate the aspiration to operate the additional paths, with a maximum train length of 775 metres – a Network Rail standard, although HP-UK currently operates trains around 600 metres long.
The scheme will allow pent up demand to be realised from the December 2019 timetable change, giving operators a few months to familiarise themselves with the new signalling.
It will also improve the reliability of the hourly passenger train shuttle between Ipswich and Felixstowe, shortly to be upgraded with the introduction of new Stadler Class 755 bi-mode units later this year.
This infrastructure improvement project is being delivered within the Network Rail Anglia Route CP5 multi-functional framework contract, which was awarded to VolkerFitzpatrick. The collaboration to deliver these works is known as the Anglia Route Collaboration (ARC).
Rail Engineer was recently invited to meet VolkerFitzpatrick project manager Dan Smith at the Trimley project offices and to see some of the work at first hand.
The scope of the project includes:
- 1.4km of additional track at Trimley;
- Closure of six pedestrian crossings;
- Construction of a bridleway bridge;
- Re-alignment of the existing public rights of way network;
- Replacement of three Automatic Half-Barrier (AHBC) level crossings with Manually Controlled Barriers with Obstacle Detection (MCB-OD);
- Replacement of one AHBC level crossing with MCB-CCTV;
- A new signalling workstation;
- A new signal interlocking;
- New lineside signalling on the branch line as required;
- Bi-directional signalling on both lines at Derby Road;
- Installation of a new 650V DC Class II signalling power supply;
- Installing a diverse Fixed Telecommunications Network (FTNx) system and associated infrastructure.
Such a diverse project required an equally varied group of contractors and suppliers to complete, and these are listed nearby.
Public rights of way
A network of footpaths and narrow lanes criss-crosses the railway along the stretch that has been doubled, necessitating detailed level crossing risk assessments. The study identified significant increase in risk to crossing users on the duelled stretch of line:
- Double track creates a particular hazard for ‘Stop, look and listen’ crossings;
- New loop exit signals could cause waiting trains to obscure the view of an approaching train;
- Trains could be held at signals, thereby blocking footpath crossings;
- Trains could be held at signals and cause existing AHBCs to ‘time-out’;
- Log of many incidents /near misses.
Accordingly, the report recommended the closure of six pedestrian crossings and conversion of the AHBCs to MCBs. As there were 10 objections to the Level Crossing Closure Order, a public enquiry was convened. The Inspector found in favour of Network Rail and the order was duly endorsed by the Secretary of State for Transport.
The project worked closely with Suffolk County Council to devise alternative provision for the six footpaths being closed, the centrepiece of which is a new bridleway/footbridge across the line near Gun Lane. New footpaths are being created alongside the railway, connecting existing rights of way with the new bridge, which has equestrian ramps at the Trimley end and footpath steps at the Ipswich end.
With advice from the British Horse Society, the Network Rail standard holly green ramped footbridge design has been expanded to fit the scale needed for horses with 3.5 metre width. Stablesoft equestrian flooring is fitted on the deck, and mounting blocks at the start of the ramps encourage horse riders to dismount and walk the horse over. The bridge is due to open at the end of July.
The three new MCBs, at Morston Hall, Thorpe and Levington, utilise Obstacle Detection (OD) technology comprising radar primary obstacle detection (POD) – the safety-critical component required to detect objects that would be a danger, such as vehicles, people or large animals – and Light Detection and Ranging system (LiDAR) as the complementary obstacle detection (COD), to reduce the risk of an object in the crossing area below 500mm from the road surface remaining undetected.
In short, the COD uses infra-red technology to detect objects such as prone bodies and small children in the space below that covered by the POD’s radar, which is mainly looking for large objects.
The conversion of the existing Westerfield AHBC is outside the immediate area of the new loop but will be affected by the increase in freight traffic. Increased road traffic resulting from a new Ipswich Garden Suburb Development of 3,500 new homes in the vicinity of Westerfield clinches the need for conversion to MCB. The configuration of the crossing in relation to footpath ramps to the platforms means that OD may not operate reliably, so this crossing will be MCB-CCTV.
The conversion of this crossing will benefit Up East Suffolk trains. Hitherto, most Lowestoft to Ipswich trains that are not scheduled to stop at Westerfield have to pause in the platform due to the lack of ‘non-stopping’ provision in the controls of the existing AHBC. This will, of course, be rectified with separate ‘stopping/non-stopping’ strike-in points for the new MCB.
However, the ‘Auto Lower’ control (provided as standard with ‘Auto Raise’ at all of the new MCB crossings) at Westerfield will not initially be used, as there have been a number of incidents including blocking back over the crossing. Red light violation cameras, already in place at Westerfield, have been installed at all the new AHBC crossings.
The signalling was controlled from the Entrance-Exit (NX) Ipswich panel. However, with the addition of the Bacon Factory curve in 1999, the increase in freight traffic, and an increase in passenger train frequency in recent years on the main line and East Suffolk lines, the workload threshold has been exceeded.
Operating Ipswich station can be challenging if trains arrive out of sequence and upset the planned platform sharing. Perturbation of passenger traffic here can react onto the Felixstowe branch. Similarly, trains using the single-line sections on the branch have to run to path in order to avoid reactionary delays elsewhere. All this gives the signaller little or no thinking time when things go awry.
With the upcoming further increase in traffic on the branch, it was decided to provide a new Alstom Modular Control System (MCS) workstation. This is positioned right in front of the Ipswich NX panel, with VDU screens low on the desk to allow the Felixstowe signaller to view trains approaching from Ipswich station/yard and coming around the chord from the north.
The Felixstowe branch hasn’t been completely expunged from the NX panel. Basic indications and train descriptions alert the Ipswich signaller to the approach of traffic from the Felixstowe and East Suffolk directions.
A new Smartlock 400 interlocking has been provided to replace the previous Alstom MkIIIA Solid State Interlocking (SSI) and this aligns with the jurisdiction of the new workstation from the mid-point between Boss Hall junction and Westerfield, through to the branch. Saxmundham signal box MCS already controls the East Suffolk line north of Westerfield. The Smartlock central interlocking processor (CIXL) contains two virtual interlockings (VIXL), with a geographical split between Derby Road and Trimley.
The CIXL is connected via a new FTNx link utilising Keymile first-line multiplexers and Cisco routers, interfacing the field long distance terminals (LDT) at a new location at Westerfield. Here, the SSI data passes onto the existing SSI trackside data links.
Diverse routing was originally provided by renting BT private circuits. This has been replaced by the installation of a new, small, green-sheathed, double insulated, super armoured cable (DISAC) 24-fibre cable, designed to be laid on the surface, running the length of the branch. SSI track function modules (TFM) interface the data link via optical data link modules.
On the ground, the signalling modifications and additions were extensive. In summary:
- Cutting the existing SSI data links into the new location areas to bring them onto the existing data stream;
- 86 location equipment cabinets have been affected (59 altered, five abolished, 22 new);
- Existing signals re-allocated with new identities relating to the new Felixstowe workstation rather than Colchester prefix;
- 25 new lightweight LED signals (21 main aspects, four three-state banner repeaters but with only ON/GREEN used, two additional route indicators either side of Derby Road);
- Recovery of SPAD indicator signals (surplus since the provision of TPWS);
- 24 new AWS (Automatic Warning System);
- 35 new TPWS (Trains Protection and Warning System);
- Five new In-bearer Clamp Lock (IBCL) point ends;
- Eight existing point ends re-controlled and re-numbered;
- Four new MCB level crossings;
- Existing Felixstowe Beach and Trimley MCB-CCTV crossings and associated Time Division Multiplex (TDM) systems re-controlled to new workstation;
- Alterations to insulated block joint (IBJ) positions to extend or reduce the length of existing track circuits;
- Provision of new standard-issue AC-immune DC track circuits to BR 867 track feed sets.
Electrical & Power (E&P)
E&P teams installed a new 650V DC signalling power supply feeder throughout the branch comprising a new power supply point (PSP) at Westerfield, upgrade and modifications to other existing PSPs, the installation of 42 functional supply points (FSP) and installation of 45km of new cabling.
The works also covers the installation of direct power and lineside power supplies for a number of level crossings, as well as new level-crossing lighting.
In addition, three points heating cubicles (PHCC) were supplied and installed along with points heating supplies, transformers and heating strips for point ends.
Track panels and switches and crossings (S&C) were brought in by road, rather than the more usual unloading from tilting rail wagons, due to limitations of the single line. There are two new modular crossovers and a single turnout. Switches are type CEN56 EVS.
Redundant trap points were removed from Trimley.
Thankfully, the line was originally well built, with a well-drained and stable formation including embankments and cuttings, well able to support the heavy pounding from today’s freight tonnage.
Staging the project
Work on the ground commenced in April 2018. The port runs no trains between Saturday evening to Monday morning, so it was possible to schedule complete possessions during this time for most weekends through to May 2019. During these possessions, stone, sleepers, rails and track panels were run out for the loop, new signals erected, new 650V DC signalling supply cables run out, SSI data links cut into the new locations, and the steel sections of the equestrian bridge (pre-fabricated at Doncaster), craned in over four weekends using a 750T crane.
A blockade over the Christmas 2018 holiday period saw the all new loop S&C installed into the existing running line using a Kirow crane. Point ends were detected and cut into the track circuit, such that a point failure would show up as a track circuit failure, a scenario covered by a special signal box instruction. The new 650V supply system was fully commissioned.
A further possession during the 2019 spring bank holiday saw the signalling system put through ‘out and back’ rehearsal testing. All the external equipment and data links were connected for testing to the new Smartlock & MCS. New signals, TPWS and AWS were correspondence tested and the existing equipment through tested, before being switched back to the original system, giving a few days for outstanding issues to be resolved.
The final commissioning of the new signalling workstation took place overnight on 28/29 May. On this night, the systems were changed over to final and assets tested that were not picked up on rehearsal were correspondence tested. Signalling data was 90 per cent factory tested in a simulation, just leaving any outstanding principles testing and those elements that couldn’t be done in the factory, such as the fringe to Saxmundham SSI and Ipswich Bacon Factory Curve Route Relay Interlocking (RRI), which can’t be simulated on the workstation. Some train-detection alterations could not be implemented prior to this commissioning.
With the signalling up and running, the installation and testing resources moved to bring the MCBs into service, one at a time, in the order Morston Hall, Thorpe, Levington and finally Westerfield, due for completion in the middle of July. During the main commissioning, level crossing indications were strapped out to fool the interlocking into thinking the barriers are down. At each stage, as a new barrier is brought into service, the temporary wiring is recovered, with barrier control inputs and outputs working live thereafter.
Inevitably, the scheme has involved temporary road closures, for which Network Rail devised a strategy in conjunction with local councils. For example, Thorpe and Morston Hall didn’t have diversion routes, so the plan was to close one and use the other as a diversion, then swap around.
The current project effectively uses up all the existing freight network capacity. Pinch points elsewhere, including the single line from Soham to Ely, Ely North single lead junctions, and Syston junctions, will need to be addressed before embarking upon further capacity upgrades on the branch itself.
The vision of entrepreneur George Tomline, who built the docks and railway back in 1875, and the subsequent commitment of port and railway owners, has assured the continuing growth of this booming port.
Thanks to Dan Smith of VolkerFitzpatrick, Tom Fitzgerald of Pod-Trak, Darren Welch of VolkerRail, and Martin Spencer, Arun Jacobs and Ian Martin of Network Rail for their help in preparing this report.
Contractors and suppliers
VolkerFitzpatrick – Principal contractor;
Volker Rail – sub contractor for signalling, level crossings, signalling design including the scheme plan;
Atkins (part of the SNC-Lavalin Group) – design for GRIP stages 3&4, TWAO support;
Mott Macdonald- GRIP 5 detailed design track, Civils, E&P, telecoms and level crossing ground plans;
Pod-Trak – Permanent way, earthworks;
Global Rail Construction- E&P – 650V signalling supply and points heating, ancillary works including under track crossings, ancillary civils;
Network Rail Telecoms (NRT) Anglia Route – telecoms testing and commissioning;
PLS Civil Engineering – LX civil engineering, pedestal bases, highway works, white lining;
Alstom – Smartlock 400 interlocking, MCS workstation and Vital Harmon Logic Controllers (VHLC) for MCBs;
Sotera Risk Solutions – GRIP 3 level crossing risk assessments;
Carver Engineering Services – bridleway bridge, steel work pre-fabricated at Doncaster and craned in over four weekends using a 750-tonne crane.
Progress Rail – Switches & Crossings
Unipart Rail – Barrier lights
Honeywell – Level-crossing radar
Collis Engineering – Lightweight signals
SPX Rail Systems – Barrier machines
L B Foster Telecoms – Red light violation ANPR (automatic number-plate recognition) cameras
CISCO – routers
Keymile – first line multiplexers
Kestrel Telecom – Hawk telephone concentrator.