New guidance for smart motorway construction

Hard shoulder lanes on smart motorways may not have enough strength to cope with heavy goods vehicles, according to infrastructure group Britpave.

Britpave has published new guidance on using concrete pavements for smart motorway construction.

Smart motorways involve active traffic management using electronic signs, CCTV monitoring, variable speed limits and hard shoulder running. The aim is to have better traffic management and to increase capacity by allowing the hard shoulder to be used as an extra lane during peak times. Highways England has announced £1.5 billion worth of contracts to turn congested stretches of the UK motorway network into smart motorways. The latest smart motorway contracts announcement will add up to 300 miles of extra lane capacity to existing motorways by turning the hard shoulder into a traffic lane.

The new guidance from Britpave, ‘Smart motorway construction with concrete’ examines a full range of situations likely to arise on the motorway network when widening or upgrading existing pavements.

In a statement Britpave said: “There is concern that the hard shoulder lanes may not have the adequate strength to cope with heavy goods vehicles. On a typical UK motorway 77% of all HGV traffic uses the inside lane. This means that with a smart motorway the hard shoulder will be under intense pressure that it may have not been designed and constructed for. The result could be premature failure and ongoing maintenance and repair.

“The solution is to design and construct the hard shoulder as a concrete pavement specifically to cope with the concentration of HGV traffic. This provides the necessary strength and long-term performance. Concrete has up to four times the strength and stiffness of asphalt and has no rutting susceptibility. Roads where the main structure is concrete are designed to last for a minimum of 40 years without major maintenance thus ensuring less disruption and more reliable journeys.”

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Hard Shoulders on motorway sections that I’ve been involved with the construction of have been designed to the same detail as the running sections of the motorway so should be strong enough to be used as an extra lane.

Crikey, this is a nightmare as all asphalt contractors just over lay with 40mm of surface course on hard shoulders for smart motorways don’t they? Let’s calm down shall we. It’s not as if we have very experienced engineering consultants obtaining pavement core information and deflectograph surveys of the existing hard shoulder, then developing the most cost effective construction to bring it up to current performance specifications.