Are all D400 manhole covers appropriate for highway use?CD 534 v0.1.0National Highways has updated CD 534, a significant set of its requirements for manhole covers and gully grates installed on their road network. First released in February 2020 and updated to version 0.1.0 as of May 2022. These updated requirements now state "E600 manhole covers are to be installed in place of D400 covers where the Annual Average Daily Traffic (AADT) of light goods vehicles travelled on a road is greater than 1,500 in each direction." BS EN 124:2015BS EN 124:2015 is the key standard for access covers and gully grates. It categorises the various places where they may be installed; from Group 1, the least demanding environment, through to Group 6, where the highest wheel loads are expected. The standard provides guidance on the minimum class to be used against each installation group. It states that anywhere on a road is a ‘Group 4’ location; ‘carriageways of roads (including pedestrian streets), hard shoulders and parking areas, for all types of road vehicles’ and requires a minimum of D400 class products. Some manufacturers of popular D400 products state on their websites and documents that their covers are ‘not suitable for carriageway use’ or are for installation only in ‘low-risk areas’. In doing so, this transfers undue responsibility onto installers to understand the complexity of the manufacturer’s product range and ensure safe products are selected. Should a cover fail under the rigours of a busy carriageway or in an area with heavy traffic braking and accelerating, the cost of lane closures and rework can be significant. It’s vital to remember manhole covers and gully grates are safety-critical products; using covers deemed not suitable for carriageway use could cost far more if damage or injuries are caused as a result of failure. When selecting a BS EN 124:2015 conforming D400 cover and frame, every customer has the right to assume it is fit for carriageway use. A Water Research Centre studyA study by the Water Research Centre (WRc) (CP373 Street Ironwork – Effective Management) concluded that structural bedding failure contributed to the failure of at least 30% of installed manhole cover and frame failures. Products which fulfil the requirements of CD 534 v0.1.0, therefore, are required to exert less pressure on the bedding material and have features to keep the covers secure within the frame. Related products
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