Are all D400 manhole covers appropriate for highway use?
Manhole covers are safety-critical products, in effect they are a bridge, expected to provide safe passage for numerous traffic types and vehicle loads within a variety of locations.
We are asked from time to time by organisations including highways authorities and construction companies about the standards which apply. Many have become aware that several manufacturers restrict the use of some of their more popular D400 class products.
The first thing to know is BS 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.
All Wrekin D400 products are suitable for installation in any Group 4 location. From our most cost-effective TriStar covers and frames to our most durable Unite range, our products have been tested and proven across the breadth of D400 locations.
Of course, installing access covers is time consuming and expensive, both in terms of the installation and the associated disruption. The cost of providing labour, necessary plant, replacement cover and frame, reinstatement, road rental and traffic management can run into thousands of pounds.
Because of these costs, Highways England (HE) has additional requirements for manhole covers installed on its network, intended to ensure product durability and extend the installation life span. HE prescribes these within the Design Manual for Roads and Bridges (DMRB), section HA104/09.
A 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 HA104/09, therefore, are required to exert less pressure on the bedding material and have features to keep the covers secure within the frame.
Wrekin Products offer a high performance, HAPAS approved, bedding system called UniPak and the largest range of cost effective, HA104/09 compliant carriageway ironwork, appropriately named ‘Highway’.
At Wrekin safety is intrinsic to every aspect of our business. We understand it is incumbent upon us as a manufacturer of safety-critical D400 manhole covers to supply products which can be used safely in any Group 4 location.