The statement, regarding the size of stones used at the wearing surface. "The size of a stone used on a road must be in due proportion to the space occupied by a wheel of ordinary dimensions on a smooth level surface. The point of contact will be found to be longitudinal about 2.5 cm and every piece of stone put into the road which exceeds 2.5 cm in any of its dimension is mischievious" was made by

• Telford
• Macadam
• Tresguet
• Sully.