Departures & Relaxations from Standards - UK Perspective

A Departure from Standard is where the designer is not following the requirements from the design manual.

Relaxations from Standards refer to situations where designers are allowed to adopt less stringent criteria than the stated standards. Basically, relaxations are minor deviations from the design standard that do not significantly impact safety or operational performance. While formal approval is not needed for Relaxation from Standards, the competent authority may review the design to ensure that the use of relaxations is justified and appropriate.

Departures are significant deviations requiring a formal approval process, including a detailed justification and risk assessment.

Why Departures from Standards?

Departures may be appropriate in a variety of situations. A few of them are as follows:

• Development/updating of design Standards don’t keep pace with emerging technology, exploration of new materials, methods of construction etc. and it might make advantageous to deviate from the Standards
• Standards cannot be reliably written to cover every situation
• Site constraints
• Disproportionate costs and/or delays
• Trials and pilots
• Innovation
• An “elastic” solution
• Departures provide a useful source of ideas for updating standards

Important Consideration for Departure from Standard

The Departure (or Relaxation) from the Standard should ensure safety standards, maintainability and giving good value for money on a whole life cost basis.

Departures from Standards for Geometric Design of Roads

The hierarchy of geometric standards provides flexible approach, where desirable minimum standards are likely to create environmental problems on people, properties and landscape and high cost.

According to Design Manual for Roads and Bridges (DMRB), there is three tier system:

1. Desirable Minimum
2. Relaxation and
3. Departures.

It enables a flexible approach for a range of situations.

For example, on horizontal curvature the manual says the minimum radius shall be say 100m for a certain design speed. If this can’t be met, and the max achievable is 85m, then the Director or Specialists from the Overseeing Organization would need to approve this as the best balance of needs.

Except where Relaxations are permitted, any variation or waiving of a requirement contained within a DMRB or Manual of Construction for Highway Works (MCHW) document must be considered to be a Departure from that Standard.

Relaxations from Standards

A number of DMRB documents contain within them provision for Relaxations where experience has shown that certain requirements may be varied within defined limits in particular situations. However, any further variation beyond these limits requires a departure.

For example, for side road visibility the design standard says that the setback visibility for the side roads shall be 9m. It then goes onto say that this can be reduced to 4.5m, and even 2.4m and for private accesses 2m in very difficult circumstances.

The responsibility for identifying circumstances where relaxations are appropriate rests with the designer, and a clear and adequate justification for not adopting the full standard must be recorded in the consideration of hazards and risks for that element of the design

 The designer must notify the Overseeing Organization when a Relaxation is to be incorporated into the design.

A design incorporating a Relaxation that has been adequately justified in the particular circumstances for which it has been adopted remains a design in accordance with Standards.

The Relaxations from Standards would need to be agreed (by say Project Sponsor), but not necessarily Approved (as they are within the given design limits).

Basic Process of Departures from Standards Submission to National Highways, UK 

The responsibility for identifying circumstances where Departures rests with the designer. A clear and adequate justification for not adopting the full standard must be submitted to the Overseeing Organization when seeking approval for each proposed Departure.

 Applications for Departures must be submitted in accordance with the procedures required by each Overseeing Organization, and each Departure must be approved before the design is finalized and prior to its incorporation into the works. At the discretion of the Overseeing Organization, the Departure approval process may be in stages reflecting the design progress.

 An approved Departure shall be considered as meeting the Overseeing Organization’s requirements for that element of the works, provided that any mitigation measures proposed by the designer or conditional to that approval are also incorporated into the design and works.

 The approval of a Departure, with or without comments, does not imply that the Overseeing Organization relieves the designer of any responsibility for the design.

Departures are approved on a location-specific basis and relate to the particular circumstances identified in each submission. A similar Departure approval may be quoted to support a new application, but each case will be considered on its own merits.

 However, as an exception, the Overseeing Organizations’ procedures may allow “bulk” Departures (when the same non-standard method or material is proposed for use at more than one location) in certain, clearly defined circumstances.

Departures from Standards Team and their Roles & Responsibilities

• Designer – identifies and assesses Departures
• Employer’s Agent, CDMC – provide advice and input as appropriate
• Proposer– formally submits Departures
• Project Manager – reviews Departure for commercial robustness
• NetServ Specialist(s) – make technical recommendation based on information submitted
• Project Manager – makes final determination taking all relevant factors into account