The increase in number of vehicles and deterioration of the existing facilities necessitates the need to improve the existing roadways and to build additional highways hence creating more work zones in cities around the globe. Two work zones one on a rural road and one on an urban road were studied to identify potential hazards in work zone and determine the most dangerous area of the work zone using risk concentration level. Confusing signs, use of dangerous devices for road closure, missing buffer, missing tapers, use of non-retro reflective devices, unprotected work area, dangerous flagging, missing safety alarms for heavy machineries, speed, aggressive driving and improper pedestrian access are the most dangerous hazards in work zone having a very high risk level. Transition area was found to be the most dangerous area of the work zone with a very high risk concentration level followed by working area with high risk concentration level, then advance warning area with medium risk concentration and finally termination area also with medium risk concentration. Proper installation and maintenance of temporary traffic control devices, use of safety attires by workers, fitting all moving machineries with safety alarms, use of retro reflective devices, protecting work activities, providing buffers for workers, and law enforcement will improve safety of the work zones.