Croft has extensive experience working with both clients and professions on Highways and National Rail projects of varying scale.

Rules and Guidance

Each government body has its own rules and guidance. The simple rule to remember is the Exclusion Zone. If you are inside the Exclusion Zone the Infrastructure Act will apply.

  • 3m either side
  • 6m above & below

There are some other rules: Cranage must not oversail a certain zone, consideration for collapsed cranes and scaffolds that can fall onto an Infrastructure asset.

Process and paperwork

The paperwork is similar to that of most government bodies as follows:

  • Pay their fee…. there is always a fee!
  • Provide an Approval in Principle (AIP, or Form 1 for Network Rail). This document lays out the principles that are to be used. The codes designed to, the idea of the structural assumptions and applied loads. Importantly it defines the Category of Design check to be undertaken for the permanent and temporary works, known as CAT I, II & III checks. The design approach requires the approval of the government body.
  • The detailed designs are undertaken and checked by the client’s consultant team.
  • CAT I – Design is reviewed and signed off by a Chartered Engineer involved on the project
  • CAT II – once the design is completed the drawings and reports are provided to a separate design engineer and an inline design is undertaken again. Internally Croft sets up an internal “Firewall” so that the second design team that was not involved on the project, can provide a fresh opinion on the design.
  • CAT III – this is similar to CAT II but the design must be provided by an independent external company. It provides a different approach, on one project over a network rail tunnel, Mott Macdonald undertook a design led by a geotechnical engineer, that considered the effects differently to our structural engineers. Both resulted in the same outcome but approached the design from a different angle.
  • During this stage LUL (London Underground), Highways and Network Rail take a back seat. They have approved the design in principle. It is for the design team and the CAT checkers to ensure it is completed in detail. They will ask for the completed design checks, but not the detailed design information. A final sign off is sent for approval and typically a one-page signed sheet is received.
  • Construction Approval - With the design approved, the construction approvals will be needed. This is where RAMS (Risk Assessment & Method Statements) are provided and approval is gained. The areas of concern may be construction sequences and loading, cranage, scaffolds, surveys etc.
Project example
Our Projects

Delivering projects at varying scale

We understand that a property is a large investment, which is why we work on an ethos of providing a personal approach to all projects. Whether small or large, when appointing Croft you will be assigned your own engineer to personally lead through your construction process every step of the way. We have the resources to deliver projects within a framework that suits you.

Croft Structural + Civil overseeing construction on site

Providing a personal approach to projects