Project: Investigation of HGV Trailer Braking Systems: Approval Standards

Reference: S0133/VD

Last update: 12/03/2008 12:04:30


The objective of this research is to investigate the effectiveness of current approval procedures for HGV trailer braking systems and to ensure that the approval procedures identify non-compliance with the requirements of Community Directive 71/320/EEC (as amended) and UNECE Regulation 13.09.

In achieving this objective the selected Contractor is expected to obtain HGV trailer brake and build data, assess for compliance and:

* verify that the braking system compatibility data supplied by the manufacturer and used by VIA during the assessment process is correct (this should include a comparison of how VIA interpret the data);
* liase with trailer manufacturers and verify that the data supplied to them by the braking system manufacturer is correct;
* carry out dynamic brake tests on a range of new HGV trailers in both laden and unladen conditions to assess compliance with the compatibility corridors found in Community Directive 71/320/EEC (as amended) and UNECE Regulation 13.09;
* compare the data recorded from the brake tests with the laden/unladen theoretical brake data curves supplied by the trailer manufacturer; and
* assess trailers tested for conformity of production (check that they comply with the build data supplied by the manufacturer).

Should shortcomings be identified in any of the above procedures, the contractor will clearly identify these and in consultation with stakeholders in the process, propose detailed solutions to overcome these shortcomings.

In addition to the objectives listed above, the contractor is invited to consider and propose further ideas that may add value to the research (these should be costed separately from the main requirements).


The majority of motor vehicles used on the road are subject to a process known as Type Approval which ensures compliance with a set of minimum construction standards. For passenger cars a pan-European whole vehicle system exists, whereas for vehicles produced in lower volumes (e.g. buses, coaches, trucks, etc), National type approval schemes apply. The complexity of these different schemes vary between Member States, but all will cover the essential components of the vehicle (e.g. brakes, steering, glazing, tyres, emissions, etc) to ensure they are fit for use on the road.

In Great Britain, however, heavy goods trailers are not subject to any form of type approval inspection prior to use on the road. Trailers are manufactured using components (tyres, lights, etc.) that may have been type approved, but there is no requirement for such components. Similarly, the brake systems on trailers are not required to be type approved although due to the complexity of the systems, manufacturers generally use type approved products. These components can be used in any combination provided that they meet with the relevant legislation in the Road Vehicles (Construction & Use) Regulations 1986 (S.I. 1986 No. 1078) (as amended) and the Road Vehicles Lighting Regulations 1989 (S.I. 1989 No. 1796) (as amended).

As a substitute for trailer type approval, manufacturers submit brake performance data for their products to the Vehicle Inspectorate Agency (VIA) Technical Services. This data is then compared with theoretical brake performance values, whereupon, on the basis of these calculations, the trailer is either approved or rejected. If rejected, the reasons are notified to the manufacturer who can resubmit corrected data. This process normally takes place as part of the trailer's development programme. However, in some cases it takes place after the trailer's first use on the road prior to the first MOT inspection.

Once in-use, HGV trailers are subject to annual roadworthiness inspections, with the first such inspection falling (at the latest) on the anniversary of first use and annually thereafter. These inspections are undertaken by VI staff who also confirm (at the first test only) the construction standards notified by the manufacturer, prior to first use, and inspect the physical components of the braking system for compliance. The trailer also undergoes a roller brake test to assess performance.

The Department is concerned, however, that some HGV trailer braking systems do not comply with the information provided during the initial pre-first use assessments. There is anecdotal evidence that the data provided is inaccurate or vehicles may not be able to achieve the performance indicated during normal (dynamic) road use. Failure to achieve the prescribed performance requirements could compromise safety on the road.

This research will investigate the issue and provide advice on possible solutions, including new or revised assessment and inspection procedures.


Watling Street, Nuneaton, Warwickshire, CV10 0TU
+44 (0)2476 355000

Contract details

Cost to the Department: £264,682.00

Actual start date: 14 October 2002

Actual completion date: 26 April 2005


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