Updated: Jul 30
The Approval In Principle (AIP) document outlines the concept for the design of the structure.
This will be used for most highway structures and incorporates the Technical Approval Schedule (TAS) which lists all the current British Standards and documents that are relevant to the design of highway structures.
According to BD2/12 (Document: Design Manual For Roads And Bridges (DMRB) ):
Summary of what an AIP is
An AIP is a standard documentation required for any structure (e.g. Bridge, retaining wall, gantry, etc.) constructed in the civil engineering industry.
This document will include:
A description of the proposed structure
The category of the structure
Details of the road it is on or adjacent to
The proposed loading criteria
The proposed method of analysis of the structure
A schedule of applicable design standard
Requirements for road restraint systems (parapets and safety fences)
Details of other structural forms considered
Conceptual drawings (if applicable)
Details of any references from Standards and any other information required by the Technical Approval Authority to determine whether the proposed design and checking regime is robust and acceptable.
In theory, prior to commencing design, the AIP must be signed by the Technical Approval Authority. In practice, programme constraints dictate that some design is carried out prior to obtaining a signed AIP, though this is at the designer/client's risk as the Technical Approval authority could require a change to the design process, resulting in the need to revisit the design.
The History of the AiP
In the early 1970s, failures at Yarra (Australia), Milford Haven (Pembrokeshire, Wales), Koblenz (Germany) and over the Danube (Austria) occurred during erection.