# Integrated Electronic Control Centre

The Integrated Electronic Control Centre (IECC) was developed in the late 1980s by the British Rail Research Division for UK-based railway signalling centres, although variations exist around the world. It is the most widely deployed VDU based signalling control system in the UK, with over 50 workstations in control centres that manage many of the most complex and busy areas of the network.
IECC consists of a number of operator’s workstations with VDU/LCD displays which depict the control area and is semi-automatic using Automatic Route Setting (ARS) – a computer-based route setting system driven from a pre-programmed timetable database. ARS can also handle severely disrupted service patterns and assist the signaller in the event of train or infrastructure failures.
IECCs were developed as an alternative to the traditional switch or button panel control, which in turn replaced mechanical lever frames. From the start, they controlled Solid State Interlockings (SSIs), a software version of the traditional relay interlocking, but existing relay interlockings may also be controlled from an IECC. The system can control as many miles of track as required, but typically around 50–100 miles.
Recently, PC-based control systems, similar to the IECC have been developed and are sold by various signalling contractors, e.g. Westinghouse Rail Systems WESTCAD.

## Early history

The concept of IECC was developed at the Railway Technical Centre in Derby during the 1980s, and in particular the initial software for ARS and SSI.
A contract for the development of an operational standard system was let in January 1987 to CAP Group, including the supply of a complete system for Yoker (Glasgow) and the ARS for the Waterloo area. This was the first time a software house became involved in railway signalling after competing against the main incumbent suppliers of GEC-General Signal and Westinghouse Signals Ltd.
The solution used off-the-shelf microcomputer technology (Motorola 68000 microprocessors and VME Bus) to host the sub-systems of IECC in high availability configurations linked via a duplicated Nine Tiles Superlink local area network. Subsequent contracts were let to CAP Group (became Sema Group in 1988) for further operational IECC systems involving the supply of turnkey hardware and software. These included the first IECC to go live at Liverpool Street in Easter 1989 quickly followed by York. In September 2020 the original Liverpool Street IECC was replaced with a new IECC Scalable system.

## Later developments

As a result of UK railway privatisation in the mid-1990s, British Rail Research was bought by AEA Technology Rail, who took over the supply of new IECCs, support for the existing installed base, and enhancements to the hardware and software. In 2006, the AEA rail business became DeltaRail (now called Resonate Group), who have developed IECC Scalable which replicates all the functionality of the original IECC on a modern hardware platform and software architecture. Following a successful six-month trial at Swindon B in 2012, IECC Scalable is now the standard for new installations, starting with Cambridge where it controls the Ely-Norwich line which has been resignalled on the "modular signalling" concept for secondary routes.

## List of IECCs in service as of 9 January 2024

| Location | IECCs | Workstations | Area controlled | ARS? |
| Ashford | 2 | 5 | Southern Region SE section and High Speed 1 | Yes |
| Cambridge | 1 scalable | 1 | Ely to Norwich (exclusive of junctions at either end) | No |
| Edinburgh | 5 (all scalable) | 9 | East Coast Main Line, from north of Berwick-upon-Tweed to south of Cupar and Fife Circle Line; also routes towards Glasgow via Falkirk, Bathgate, Shotts and Carstairs. | Yes |
| Harrogate | 1 (Scalable) | 1 | Harrogate to Leeds (exclusive) | No |
| Liverpool Street SDC (Service Delivery Centre) | 5 (all Scalable) | 10 | Great Eastern Main Line to Marks Tey, Bishop's Stortford/Stansted North Junction/Stansted Airport and branches | Yes |
| Marylebone | 1 (Scalable) | 2 | Chiltern lines to Aynho Junction near Banbury | Yes |
| Thames Valley Signalling Centre | 10 (all Scalable) | 14 signalling 1 CCTV crossing keeper | Great Western main line from London Paddington to Bristol Parkway and Temple Meads, Swindon and branches, plus Didcot to Oxford, and Reading to Westbury (exclusive). | Yes |
| Upminster | 3 (all Scalable) | 5 | London, Tilbury and Southend line and North London line | Yes |
| York ROC | 3 (all Scalable) | 7 | East Coast Main Line, from north of Doncaster to north of Northallerton and Leeds area | Yes |
The following installations are not true IECCs of the BR/SEMA/DeltaRail design. They are VDU based signalling control systems with a similar "look and feel" but in most cases they do not incorporate Automatic Route Setting. Some locations shown below are interim installations which will eventually move into larger signalling control centres, such as Leamington and Madeley, which in time will move to the West Midlands Signalling Centre.
| Location | Workstations | Area controlled | ARS? | Equipment |
| Bournemouth | 1 | Dorset coast | No | VICOS (Siemens SIMIS - W) |
| East Midlands Control Centre, Derby | 5 | Sharnbrook to Spondon, Attenborough to Trent East, Sheet Stores to Stenson Junction, Toton Yard, Erewash Valley Line, Pinxton Branch, Clay Cross to Tapton, Narborough - Leicester | Yes | WestCAD |
| Leamington Spa | 1 | Banbury to Warwick | No | WestCAD |
| Madeley (Shropshire) | 1 | Oxley (exclusive) to Shrewsbury (exclusive) via Telford and Wellington | No | WestCAD |
| Marston Vale | 2 | Fenny Stratford (nr. Bletchley) to Bedford St. Johns | No | GE MCS |
| Former Rugby Power Signal Box | 1 | Formerly controlled Hunsbury Hill (exclusive) to Hillmorton Junction (exclusive) via Northampton. (The WestCAD controlled the original Solid State Interlocking.) Control transferred to Rugby SCC on 3 June 2012 | No | WestCAD |
| Rugby ROC | 3 | Stafford Workstation: Penkridge / Milford & Brockton - Basford Hall (exclusive) Colwich Workstation: Polesworth (inclusive) - Shugborough Tunnel / Hixon Claydon Workstation: Bletchley - Gavray Junction | Yes (Stafford only) | WestCAD MCS Infinity (Claydon) |
| Rugby Signalling Control Centre | 5 | West Coast Main Line between Kings Langley (exclusive) and Polesworth (exclusive) also Three Spires Junction (exclusive) to Nuneaton, Arley Tunnel to Hinckley (exclusive) and Brandon to Rugby. | Yes | GE MCS |
| Wembley Mainline Suburban Workstation | 1 | South Hampstead to Watford Junction DC Lines | No | WestCAD |
| Stoke-on-Trent | 2 | Hixon / Stone to Crewe/Macclesfield | No | GE MCS |
| Colchester PSB | 6 | Marks Tey - Manningtree, Colchester - Alresford, Alresford - Clacton/Walton-on-the-Naze, Westerfield - Felixstowe*, Brundall - Great Yarmouth/Buckenham*, Buckenham - Lowestoft + Oulton Broad South*. | Yes/No (Workstations marked with (*) do not have ARS) | GE MCS |
| West Midlands Signalling Centre | 4 | Jewellery Quarter to Warwick/Stratford-upon-Avon via Birmingham Snow Hill and Brandon/Milverton to Hampton-in-Arden/Three Spires Jn, Wolverhampton North Jn (excl.) to Bilbrook | No | WestCAD |
| West of Scotland ROC (WSROC) | 7 | Glasgow Central to Rutherglen, East Kilbride, Paisley Canal, Ayr, Largs, Wemyss Bay and Gourock | Yes | GE MCS |
| Port Talbot | 1 | Llanharan to Baglan | No | WestCAD |
| Abercynon | 1 | Abercynon to Merthyr Tydfil and Aberdare | No | WestCad 1 x SSI Interlocking |
| Wales ROC (WROC) | 10 1 CCTV crossing keeper | Ebbw Workstation (Newport - Cardiff Long Dyke) ∞ Newport Workstation (Newport - East Usk) ∞ East Usk Workstation (East Usk - Severn Tunnel) ∞ Severn Tunnel Workstation (Severn Tunnel to Pilning and Awre) ∞ Cardiff VOG (Cardiff - Cowbridge Road and Leckwith - LLantrisant) ° Cardiff Valley (Cardiff Bay - Rhymney) ° Cardiff Main (Cardiff Long Dyke - Leckwith) ° Shrewsbury North (Shrewsbury - Gresty Lane) ∞ ¤ ៛ Port Talbot - Swansea ∞ | No ∞ Yes ° ARF ៛ | 7 x WestCad ∞ 3 x GE MCS ° 15 x Westlock Int Remote Westrace Int ¤ |
| East London Line Signalling Control Centre | 2 | Highbury & Islington station to New Cross/New Cross Gate | ARF | WestCAD |
| Havant | 3 | Portsmouth Harbour to Fareham and Rowlands Castle | No | VICOS (Siemens SIMIS - W) |
| Saxmundham | 1 | Oulton Broad South - Westerfield. | No | GE MCS |
| Yoker | 2 | Glasgow North suburban area | Yes | GE MCS |
| York ROC | 13 | Sheffield Rotherham North Lincolnshire Huddersfield Halifax Brough Hartlepool Middlesbrough Kings Cross Finsbury Park Wood Green Langley Hitchin | Yes | WestCAD |
* ↑ Nottingham, Trent & Burton Workstations now have Hitachi ICS TREsa (ARS+) commissioned.
* 1 2 These systems (WestCAD, Westinghouse Control and Display; GE MCS, General Electric Modular Control System) which are already in existence, are planned to be upgraded when the supplier's version of ARS has received Network Rail approval.
* ↑ As of 2/4/2017, Yoker IECC has been converted to GE MCS with Hitachi ICS TREsa