Traffic signs and signals Electronic traffic controls 127 Programmable controllers 64 Data processing 53 Roads 28 Control systems 20 Interchanges and intersections 20 Traffic engineering 11 Design and construction 8 Electric controllers 8 Wireless communication systems 8 Safety measures 6 Traffic flow 5 Traffic safety 5 Adaptive control systems 4 Signalized intersections 4 Signs and signboards 4 Visual perception 4 Infrared technology 3 Maintenance and repair 3 Automobiles 2 Communication and traffic 2 Electronic circuit design 2 Field programmable gate arrays 2 Fuzzy logic 2 Human engineering 2 Internet social networks 2 Internetworking (Telecommunication) 2 Lighting 2 Mobile communication systems 2