Drink & drive has caused increased rate of commercial vehicle accidents in the world due to slow response of judgment and reasoning. According to research study 70 % accidents are happened due to drunk & drive, it will cause loss of human life and economic damage. Research has proven this, that drunk drivers exhibit aggressive driving behavior and applying more force when breaking. While public health awareness and legal restrictions can assist in educating and discouraging people from drunk & drive, a more full proof method is not available in the market for commercial vehicles. Currently low cost, fail-safe on board alcohol detection and vehicle safety system is need of hour. This Paper deals with design & development of low cost active on board breath alcohol detection system and validation. Selection of alcohol detection sensor, controller design, logic programming, system packaging, accurate & precise positioning of sensors and on vehicle validation are the key highlights in design & development. System has been tested on vehicle to check response time & alcohol detection accuracy of sensor, preciseness of sensor location and validation of safety features like SMS & voice call alerts & vehicle geo-graphical location to the fleet owner, vehicle engine auto cut off in stationary condition for disabling vehicle cranking and for moving vehicle gradually engine torque reduction to stop the vehicle on alcohol detection.