EM-7720-100. The Forest Service, U.S. Department of Agriculture, developed this book for use in the preparation and administration of contracts for the construction of roads and bridges on the National Forest Development System under Public Works Contracts, or as a condition of Timber Sale Contracts. This book contains the Standard Specifications that commonly apply in Public Works and Timber Sale Contracts. Divisions are structured as follows: General Specifications; Engineering; Earthwork; Stuctural Embankments; Bases; Bituminous Pavements; Bridge Construction; Incidental Construction; Materials.