SIC 42120 Section F — Construction

Construction of railways and underground railways

3,971 active UK companies registered under this classification.

SIC Code 42120 (Construction of railways and underground railways) is a UK Standard Industrial Classification code used by Companies House to categorise business activities. Companies registered under this code operate in the Construction of railways and underground railways sector, which falls under Section F (Construction) of the SIC 2007 framework. There are currently 3,971 active companies and 4,328 total registrations under this classification.

Sector pulse: concentration is strongest in London and CARDIFF, with 39 new incorporations recorded in 2026.

3,971 Active Companies
4,328 Total Registered
39 New in 2026
London Top Location

Incorporation Trends

New Construction of railways and underground railways companies registered per year.

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Construction of railways and underground railways Companies

Showing 1–25 of 4,413 companies.

PL

019 PLANNING LTD 10919549

● Active Liverpool Est. 2017
VL

046 VENTURES LIMITED 09116686

● Active London Est. 2014
EL

10/10 ELECTRICAL LIMITED 11407093

● Active Waltham Abbey Est. 2018
L

1089 LTD 11723652

● Active Sittingbourne Est. 2018
L

1313 LTD 13112241

● Active Collier Row Est. 2021
CL

141 CONSTRUCTION LTD 10482564

● Active Wembley Est. 2016
RP

1435 RAILWAY PROJECTS LTD 15986975

● Active London Est. 2024
L

1707 LIMITED 13821325

● Active Billericay Est. 2021
SL

1AM SOLUTIONS LTD 16494010

● Active Dagenham Est. 2025
L

1MLV LIMITED 12412885

● Active London Est. 2020
IL

1ST INRAIL LIMITED 06252002

● Active Cheshire Est. 2007
CL

2AA CONSTRUCTION LIMITED 15639661

● Active Harlow Est. 2024
CA

2AB CIVILS AND RAIL SERVICES LTD SC869687

● Active Hawick Est. 2025
L

2JEM LTD 09520060

● Active Holloway Est. 2015
KR

3 K RAIL CONSTRUCTION LIMITED 10558913

● Active Rochester Est. 2017
FR

31 FEBRUARY RAIL LIMITED 10367278

● Active High Wycombe Est. 2016
L

3DGN LTD 15170298

● Active Skelmersdale Est. 2023
L

3JAIS LTD 11942371

● Active Orpington Est. 2019
L

3JM LTD 07328883

● Active Yateley Est. 2010
RR

3RD RAIL RESOURCE LTD 13166550

● Active London Est. 2021
OL

4LIFE OPERATIVES LTD 09418961

● Active Prescot Est. 2015
L

4NE LIMITED 10205307

● Active Cardiff Est. 2016
L

540 LTD 16624299

● Active Meopham Est. 2025
L

5STARRAIL LTD 14958399

● Active Bromley Est. 2023
RL

66 RMT LTD SC615040

● Active Hamilton Est. 2018

Frequently Asked Questions

What is SIC code 42120?

SIC code 42120 represents "Construction of railways and underground railways" in the UK Standard Industrial Classification (SIC) 2007 system. It is used by Companies House to categorise the primary business activity of registered UK companies. It falls under Section F — Construction.

How many UK companies are classified under SIC 42120?

There are currently 3,971 active UK companies registered under SIC code 42120 (Construction of railways and underground railways), out of 4,328 total registrations.

Where are most Construction of railways and underground railways companies based in the UK?

The top locations for Construction of railways and underground railways companies in the UK are London, CARDIFF, LIVERPOOL, GLASGOW, ASHFORD. London typically leads in company registrations across most sectors.

How do I find a specific Construction of railways and underground railways company?

You can browse all companies on this page, or use CompanyPulse's search at companypulse.co.uk/search to find a specific company by name or company number. Each company profile includes directors, financial data, risk analysis, and filing history.

How many new Construction of railways and underground railways companies were incorporated in 2026?

39 new companies were registered under SIC code 42120 in 2026. CompanyPulse tracks all new UK incorporations in real time via the Companies House data stream.