Durable Pavement Preparation

In the sections on various aspect of provision of drainage for the Great North Road, the name of Macadam arises with mention of his major published work in 1824, noting his emphasis on the importance of drainage and the preparation of the road surface. Just four years later in June 1828, the Surveyor of Roads and Bridges, Edmund Lockyer, had set out detailed instructions to his Assistant Surveyors about the construction of drains and pavements, produced by the Government as Regulations for the Guidance and Conduct of the Road Department. We have given many examples of the way the Assistant Surveyors met Lockyer's requirements on drains, culverts and races.

Let us now turn to what Lockyer further proposed for the preparation of pavements:

It is also necessary that Assistant Surveyors should be particular in the selection of the material for laying on the road. The best in the Colony is the whinstone or ironstone. There is also a hard blue coloured stone, which when broke to the size of one inch and a half to two inches is diameter and laid about six inches in depth and twenty one feet wide, with a coat of ironstone gravel over, first passing it through a screen to let the dirt pass through, makes an almost imperishable road. The latter material is easily found where an ironbark forest or scrub is seen or met with, there is certain to be found plenty of gravel. Regulations for Roads Department, Box 4/1984, CY905, Archives of NSW.

In some parts of the road line, it crossed considerable lengths where the surface was basically a rock platform. High spots were picked across the width of the road. Where the surface had cracks or gaps in it, those were filled with broken stone up to the level of the main surface. The photograph was taken near Sampson's Pass where the road is badly eroded. It does show the rock platform which had been picked to a fairly level surface. Further along is evidence of the gravel and rock pieces used under the top surfacing. This area of road and those where filling had been completed up to about six inches below the final surface were covered with screened broken stone of about 1.5 to 2 inch gauge. The final addition was of a layer of crushed sandstone or screened gravel, raked over the broken stone layer. Gravel was not always available nearby on some sections of the road. However, at numbers of locations along the road, Lockyer's advice was obviously being followed because excavations up to a metre in depth have been found, where there was suitable gravel to make the good road surface.

Again the Weekly and Monthly reports indicate how heavy this work was. Up to 15 men were involved in picking gravel, with the same number shovelling it into carts and four men spreading the gravel on the road surface. On Devine's Hill Ascent, the No.3 Iron Gang carted 2,400 loads of gravel for spreading on that section of the road. Many of the weekly reports describe th tasks undertaken as breaking stone, picking gravel, shovelling gravel and raking gravel.

As Karskens notes, this aspect of the construction of the road is the most transient with more wear, damage and alteration than any other aspect. There are nevertheless small sections at various locations which appear to be original as a result of their strong resemblance to contemporary instructions and descriptions. The remnants occur exclusively in sections of the road, long abandoned, making them safe from extensive wear and maintenance operations. One example given reads as follows:

The 2 km abandoned section scaling Devine's Hill, has several slightly different examples of this type of broken stone pavement.
Near the base of the hill, at points where channels have been eroded across the roadway, the fill of large broken stones is exposed with the remnants of an upper layer of compacted stone, 75-100 mm gauge [3 to 4 inches]. Figure 8 [from her paper] shows also the remnant of a course of ironstone gravel, 12mm [half inch] gauge and finer, running continuously along the outer edge of the road. Another abandoned section at Mt McQuoid also illustrates a version of Lockyer's instructions. Two sections of broken stone pavement are intact. The first is 6 to 7 metres wide and comprises compacted stone up to 100 mm [4 inches] in diameter. An earthen table drain on the east side reveals the thickness to be approximately 150 mm [6 inches].

On Devine's Hill, there was a collapsed culvert and there was evidence of the structure of the pavement surface. Just back from the collapse, the surface layer showed the gravel (half inch and finer) which had been used. Closer to the hole and in the area eroded by water, the larger compacted stone remnants were present. In the picture, the gravel can be seen on the top left while the larger broken stones can be seen at bottom right. Wear and tear, erosion, damage and alteration have thus had a major impact on what can be viewed nearly one hundred and seventy years after the construction of the Great North Road.