§ Lieut.-Colonel Bromley - Davenportasked the Minister of Transport as a result of altering in places the proposed vertical alignment of the 26-mile length of the Birmingham—Preston motorway, between Preston and Warrington, in order to reduce to a minimum excavation of material that would be suitable 57W for use in embankments, how many gradients have been changed; what is the length of each; what was the original proposed gradient; and to what it has been changed.
§ Mr. MarplesFive gradients and eight vertical curves have been amended, the total length of which amounts to 6.45 miles. In all cases the revised gradient is well within the acceptable gradient for motorways. The following table gives the detailed information for the lengths affected.
Changes in Gradients Length in feet Gradient Before revision After revision 7,000 1 in 500 1 in 476 5,800 1 in 156 1 in 157 1,800 1 in 100 1 in 166 1,600 1 in 62 1 in 54 1,000 1 in 125 1 in 200
Changes in Vertical Curves Length in feet Rate of change in curvature Before revision After revision Per cent. Per cent. 1,300 0.13 0.12 1,700 0.04 0.03 2,300 0.215 0.210 2,500 0.060 0.091 1,600 0.271 0.311 3,100 0.057 0.047 2,400 0.029 0.020 2,000 0.04 0.10