UnPS is a specialist tunnelling and underground space design consultancy with a world-class record of innovation. We have been responsible for the detailed design of more than £2 billion of the most prestigious tunnelling projects in the UK.

Our team can demonstrate an unparalleled achievement in bringing new ideas to market, and we pride ourselves on seamless interfaces between tunnel design and construction that have helped deliver more than £100 million of value engineering savings to our customers.


UnPS evolved from the engineering team within Morgan Sindall’s tunnelling business, becoming an independent consultancy in 2003.

We are proud to demonstrate a world-class record of innovation, and have been responsible for virtually every significant advance in methodology and materials to the industry. These include:

  • Steel fibre reinforced tunnel linings
  • CombiShell™ method of tunnelling
  • ‘Grey Rock’ tunnel design philosophy
  • Variable diameter slipformed shafts
  • Computer-guided caisson shaft sinking
  • LaserShell™ method of tunnelling
  • TunnelBeamer™
  • MultiMode™ Tunnel Boring Machine
  • Zero-Impact aquifer tunnelling method
  • Single-pass tunnel lining system for hydraulic tunnels
  • Composite SCL system
  • Quadracurve™ shaft lining system
  • UltraShell™ tunnel lining system
  • SlipStress™ shaft lining system
  • SmartShell™ tunnel lining system

View more information on our innovations here

“We are proud to demonstrate a world-class record of innovation”


Our teams have won and been shortlisted for numerous industry awards, including the ‘Design Innovation of the Year‘ award as part of the NCE Tunnelling and Underground Space Awards 2015.


Our People

David Clayton


A geotechnical engineer with 11 years’ tunnelling experience, David joined UnPS in 2008 as a tunnel design engineer, having previously worked as a site engineer.

His project experience includes temporary and permanent works design on various projects including Belfast Sewers, Brixton to Honor Oak Thames Water Ring Main South and Lee Tunnel. He has worked in a variety of project, technical and site-based roles. These include site engineer, tunnel design engineer, engineering manager, technical manager and senior project manager, where most recently he managed to completion the concept design for the proposed 22 kilometre subsea tunnelled crossing under Morecambe Bay for National Grid.

David won the British Tunnelling Society Harding Prize in 2013.

Andy Machon

Senior Engineering Manager

A chartered civil and structural engineer, Andy has 25 years’ experience working on both the design and construction elements of major, high profile infrastructure projects in the UK.

Andy has worked in a variety of roles including Section Engineer and Planning Engineer on the Thameslink rail project, Design Manager on Heathrow Terminal 5 road and rail tunnels, and Senior Engineering Manager on both the Belfast Sewers and Lee Tunnel projects. As Senior Engineering Manager he held responsibility for the delivery of the design packages and interface management with Mechanical, Electrical, Instrumentation, Controls and Automation (MEICA).