Roads 116 Transportation 116 Design and construction 103 Traffic safety 102 Intelligent transportation systems 86 Safety measures 83 Pavements 80 Testing 78 Automobiles 67 Traffic accidents 65 Planning 64 Maintenance and repair 62 Prevention 61 Research 51 Technological innovations 44 Performance 42 Concrete bridges 40 Drunk driving 40 Bridges 30 Drinking and traffic accidents 30 Local transit 30 Motor vehicles 30 Pavements, Concrete 29 Traffic engineering 29 Study and teaching 28 Evaluation 26 Highway communications 25 Standards 24 Traffic signs and signals 24 Data processing 21