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Introduction to Standard Designs and Details

The development of the Standard Designs and Details (SDD) has been undertaken by Network Rail to improve safety, asset reliability and increase efficiency. Their development is linked to Network Rail's overall business objective, to improve reliability of the railways and reduce the funding requirements for on-going management and maintenance of the network. The basis of the SDD focuses on one main area that derives from these issues:

• Ensuring that the design meets Network Rail's requirements

Network Rail's Requirements

Network Rail's requirements are split between two areas, delivery and function:

Delivery Requirements

The SDDs have been taken to a stage where Form As and Form Bs for each aspect covered have been submitted and approved. This leads to the following benefits:

• A reduction in the design development timescales and costs

• Minimising contractor and sub‐contractor costs associated with uncertainties in detailing requirements

• Streamlining the technical approval process for commonly used designs and details

Functional Requirements

The SDD have been developed to ensure satisfactory performance of the asset under both normal operations and abnormal operations (both planned and unplanned). A further consideration has been Network Rail's requirement to reduce the volume of maintenance and management costs through the adoption of good practice. This leads to a number key design drivers including:

• Failure modes: Critical failure modes shall give warning, and alternative load paths shall be provided for potential local failures.

• No hidden details: All main structural elements shall be visible from at least one side.

• Robustness: It is desirable for elements of the structure to have a degree of robustness so that they are not damaged by unforeseen events disproportionate to the cause.

• Capability to support load.

• Acceptable deformations.

• Structure gauge requirements: The footbridges have been designed to cater for a range of positions of the structure gauge allowing their wide use.

• Safe working environment: The bridges have been designed to minimise the risk to people on or about the bridge.

These functional requirements are requirements of Network Rail standard NR/L3/CIV/020. This standard has been used and the requirements therein met in developing the standard designs and details.

A library of standard designs and details for non-station and non-canopy-station footbridges that meet these requirements has been produced. This document contains guidance on the use of these standard drawings, including advice on the following:

• The elements and options contained within the suite of standard designs and details.

• Instruction on configuring a design using the standard designs and details.

• Specific design restrictions and design assumptions.

• Advice on circumstances when the standard designs and details may not be used.

• Installation guidance.

• Safety/CDM/environmental issues.

• Safe by Design Principles (SbD)

The library will be maintained and distributed by Network Rail to its stakeholders and key external suppliers for adoption across the network at a national level.

The standard designs and the advice within this document are in accordance with the Department for Transport "Accessible Train Station Design for Disabled People: A Code of Practice" except where noted in this document. Although it is not necessary for non-station footbridges to comply with this advice, it has been assumed as best practice. Sites are all unique and it is by preparing an access statement that issues surrounding accessibility can be duly considered and an appropriate scheme delivered.

Benefits Delivered by the Footbridges Standard Design and Details

The Footbridges Standard Design and Details have been developed to improve time and cost efficiencies of replacing existing footbridges and level crossings. This is required as part of Network Rail's on-going maintenance and improvements works.

In all cases the specific scheme designer shall carry out a risk assessment to ensure appropriate applicability and suitability of the Standard Design and Details to the site.