asked the Minister for Local Government if he will state (a) the formula used by the Garda Síochána in 1928 when estimating road traffic density; (b) the number of miles of roads in the environs of Dublin where vehicles may be presumed to be circulating at the rate of over 400 per hour (assuming that the density increases in proportion to the total increase in vehicles licensed since 1928); (c) the number of miles of road now requiring double carriageways of 24 feet width, using the formula prepared by the engineering staff of the Department of Local Government about 1944; (d) the number of miles defined at (e) using any of the well-known methods of calculation in use abroad.
Ceisteanna—Questions. Oral Answers. - Dublin Road Traffic.
(a) The census of traffic taken in 1928 by the Garda Síochána at various points throughout the country was on the basis of a count of vehicles passing the selected points. Beyond assigning an assumed average weight to each vehicle for the purpose of determining the weight of traffic, no particular formula was used and no estimate made of traffic density. The details of the census will be found in the Report of the Department of Local Government and Public Health for 1928-29. Subsequent investigations in the Department led to the determination in 1944 of a formula for estimating road traffic density for design purposes, based on the results of the 1928 census.
(b) On the assumption referred to— 12½ miles.
(c) In 1944 it was recommended that the provision of dual carriageways would be justified where the traffic density for design purposes might be assumed to exceed 400 vehicles per hour. The application of the formula for the design standard for 1950 traffic shows that the same mileage of road as indicated at (b) was assumed in 1944 to reach a traffic density of 400 vehicles per hour in 1950 and on the basis of the formula in question the reply is, therefore, 12½ miles.
(d) The information asked for by the Deputy cannot be prepared without particulars of the methods of calculation which the Deputy has in mind.