Concrete Roads
and Their Construction

IN OTHER COUNTRIES 101 gate available in this class of pavement. This road was completed in February, 1916. Durham Street.—This was done with one-coat work 7 in. thick of 5 to 1 concrete, the traffic conditions not being so severe as in the preceding road, and it was left untreated and has stood quite satisfactorily since its completion in October, 1916. Park Road forms a portion of Auckland’s busiest traffic outlet, and lies immediately eastward of the important reinforced concrete viaduct known as Grafton Bridge, which is surfaced with com- pressed Neuchatel asphalt. The road was completed in July, 1917. It carries mixed traffic, most of which is fast travelling, and includes heavy petrol motor-wagons and chars-a-bancs, but no motor-buses similar to those so common in London, the number of vehicles counted being over 2,000 per day of ten. hours. The work was done in two halves to prevent stoppage of the traffic, and was much delayed by difficulty in obtaining shingle owing to bad weather, and this resulted in some shingle being used which was not absolutely first class, and also in the street being opened up for traffic sooner than was advisable. This caused the engineer to cease using shingle for aggregate and to substitute broken basalt and sharp sand. The change was made during the progress of the Park Road job, which was a one-coat pavement of 5 to 1 concrete, 8 in. thick, and the bays done with the basalt and sand aggregate showed enough superiority to the rest of the work to justify the alteration made. With the exception of a short length of the basalt and sanct concrete, the whole surface was treated with a dressing similar to that used on Little Queen Street. In all the streets paved since 1917 the paving has been one- coat work of concrete composed of clean basalt chippings and screenings varying from l|-in. gauge to “ fines ” mixed with 25 per cent, of sharp beach sand free from shell and gauged with Portland cement in the proportion of 5 of aggregate to 1 of cement, but prior to the concrete being laid the sub-grade is sprinkled with 2|-in. clean basalt road metal as a measure of economy. In all cases the sub-gx'ade is carefully prepared and rolled solid, and steel rod reinforcement is laid transversely over trenches likely to cause trouble by subsidence.