asked the Minister for Local Government if he can give comparable estimates of the different methods of construction of the dual carriageway to Naas, County Kildare, including cost per mile, man hours and employment per mile, percentage of native materials used, non-skid qualities, maintenance, probable duration, and any other similar data available.
Ceisteanna—Questions. Oral Answers. - Naas Dual Carriageway.
14.
The different methods of construction in use on the dual carriageway between Dublin and Naas are rolled asphalt on pitching and gravel in Kildare, and, in Dublin, reinforced concrete. It is not possible to give precise comparable cost figures of the two types of construction by reference to the work which has been undertaken to date on this road and any comparison must be subject to a number of qualifications arising from various factors such as the period of execution, the standard of the old road, differences in terrain, special problems such as drainage, and the different methods of execution. Subject to the foregoing reservations, the present indications are that the cost of construction per mile on this road in both Dublin and Kildare will be of the order of £135,000 including acquisition costs.
A more reliable guide, perhaps, to the comparative costs of flexible and rigid (concrete) construction is, however, available in alternative tenders received by Dublin County Council in 1962 for the Brownsbarn to Millbridge section of this road, which is about 1.3 miles long. The lowest quotation per mile for construction in asphalt surfacing on a lean-mix base was £92,730 compared with £97,173 per mile for reinforced concrete. These figures were exclusive of special drainage works, of land acquisition, fencing and compensatory works. Dublin County Council opted for the concrete construction, although it was slightly dearer, chiefly because it is generally accepted as being a more durable type of road. A concrete road of the standard of that being constructed in County Dublin at present may be expected to last for 30 to 40 years with only minor maintenance, as compared with some 20 years for the flexible type of construction. Average costs for normal maintenance in both cases are estimated as being in the range of £100-£200 per mile per annum. Precise information is not available of the comparative employment content per mile of the two methods. The average number of men employed on the Kildare section over the past ten years is about 45. The length of road concerned is 5¾ miles. Average employment on the County Dublin section since work began some two years ago is 30 men. This includes employment on construction by contract on 3.3 miles and on direct labour works of drainage, etc. on 6.8 miles approximately.
It is not possible to give the actual percentage of native materials used, but it may be accepted that with the exception of steel reinforcement and bitumen, which are estimated at £5,000 per mile for the rigid construction and £3,000 per mile for the flexible construction, all materials used are native materials. Both types of road have high non-skid values under normal circumstances, while the concrete has better light reflective qualities.
The question as to which type of construction is the more advantageous is one which must be decided in the light of the particular circumstances in each case.
In view of what the Minister has said about the non-skid property of concrete, could he say whether any other surface is to be superimposed? It is common knowledge that a concrete road is very liable to cause skidding in any icing conditions at all.
My information is that both types of road have high non-skid values in normal circumstances. If Deputy Sweetman wants any further information, he had better get a civil engineer to do a thesis for him on it.
Could the Minister say when the dual carriageway between Dublin and Naas will be completed?
No.