The present edition is enlarged further by addition of field CBR test, determination of modulus of sub grade reaction and field permeability tests. The extended bibliography has also been provided in this edition. Wherever necessary, grammatical corrections have also been done. The chapter of case studies has been provided with more information to make it more lucid, informative and users' friendly. In some copies of last editions, flow chart of soil classification could not be added. The flow chart has thus been made mandatory as part of Chapter 1. In the present revised and enlarged edition, preliminary, rock investigations have also been discussed. We are sure that the readers will find this edition much more useful and shall be benefited in their professional lives.