§ Mr. Iain Millsasked the Secretary of State for Transport if he will list the experimental road surfacing materials which are in use on roads for which he has responsibility; and what assessment has been made of their effectiveness.
§ Mrs. ChalkerThe Transport and Road Research Laboratory has 153 lengths of experimental surfacing under observation on heavily trafficked roads. The influence of different types and proportions of bitumen—including additives such as organic polymers—stone and sand on road performance is being assessed in terms of resistance to skidding and rutting, riding quality, tyre noise and, with certain special materials, spray reduction. Formulations of 11 proprietary surfacing materials are included.
250W
§ Mr. Iain Millsasked the Secretary of State for Transport if he will make a statement on the assessment by the Transport and Road Research Laboratory of the use of an experimental road surfacing material on the A1 the name of which has been supplied to him.
§ Mrs. ChalkerFive variants of the proprietary material, the name of which has been supplied, were laid on A1 in 1975 alongside eight other non-proprietary surfacings. Measurements indicated that the surface texture, required for high-speed skid resistance, of the sections surfaced with the named material was lower than that specified by DTp and did not increase with time. The material did, however, provide good riding quality for rather longer than a standard bitumen macadam surfacing, but at a higher first cost. Results of the assessment have been published in TRRL supplementary report SR476.