Reprieve for single drum rollers

Single drum rollers (600kg/m-1,000kg/m) have been returned, temporarily at least, to the list of approved equipment for the reinstatement of openings in highways - pending laboratory tests next month on their effectiveness.

The move follows the Highways Authorities and Utilities Committee meeting on 24 July and has been approved by the secretary of state for transport.

In early September an independent test centre will start the work in conjunction with the manufacturers and contractors. Both the test parameters and methodology are to be agreed by the end of the month and the testing, including site evaluation,  is expected to take a year.

The manufacturers contend that their latest equipment can provide satisfactory compaction in eight passes or less. In addition, some preliminary tests undertaken by a contractor are believed to indicate that when the materials and procedures are used, the performance of single drums is satisfactory.

The actual revision will see 1,000kg/m replaced by 600kg/m on section S10.3.4.1(b). On Table A8.3, the 600 - 1,000kg/m category has been reintroduced with a minimum of 10 passes and 12 passes respectively for 40mm and 60mm compacted lift thickness only.