ROAD EXPERIMENT.

Shannon News, 3 April 1928, Page 2

ROAD EXPERIMENT.

bitumen AND pumice on taupo ROAD. APPLICABLE TO SANDY AREAS. A new method of treating pumice roads is being tried out by the Main Highways Board near Taupo. , This consists of treating the pumice with a light asphaltic oil, the resultant surface after traffic has ironed it out, being practically a bituminous pavement. How the surface will wear has, of course, yet to be determined, but Mr A. Tyndall, engineer to the Main Highways Board, who has just returned from supervising' the work, states that the experiment looks distinctly promising .(states the Cambridge “Independent i,> ). A section of roadway about 1000 ft long has been treated, the work occupying three days. The section is situated about two miles from the Terraces Hotel on the Taupo-Napier Road. The method adopted was to tear up the road surface and then to spray it with an asphaltic road oil of about the same consistency as thin tar, nine-ten-ths of a gallon to the square yard being applied. The loose sprayed sufface is then thoroughly mixed by running disc harrows over it. Next comes another spraying of road oil, same quantity being used as before. Another discing follows, and then a power grader is used to work the mixed material in windows to the side of the road. Finally the grader spreads the new thoroughlyyinixed pumice and oil in a layer about two inches thick over the road, and'it is left for traffic to iron out. When first laid this surface is ot a brown colour, but as the traffic rjins over it, it presents a black appearance, and is compacted into a bituminous pavement about inches thick. Mi Tyndall states that a lorry laden with rails, representing a gross weight of 7 tons, ran over the section just treated and only compressed the surface a quarter of an inch. The work is on the same lines as tried out last year on sand and sandclay roads in California and New Mexico . If the experiment is a success it may revolutionist road conditions in the pumice areas in the interior of the North Island. Stone for road-making is scarce in these partsj but if a durable surface can be created by the application of road oil direct to the pumice itself, it will be possible to have good, hard-surfaced highways right through the pumice country at a comparatively smallexpense^^