Increasing and projected shortages in non-renewable energy sources have directed attention toward the potential for using regenerated energy from road traffic. There are currently three primary techniques for harvesting energy from roadways-piezoelectricity, thermoelectricity and photoelectricity although, to date very few studies have focussed on the potential for integrating two or more of these, with most examining the application and optimisation of single-mode harvesting. To address this gap, this paper reviews and analyses the body of past research on road energy harvesting with the goal of developing a 'dynamic-heat-light division recommendation' based on the literature. From this research, a new concept of 'e-Roads' is proposed and defined in detail. If full use can be made of roadways as e-Roads under the division recommendation made in this paper, these structures have the potential to serve as one of the largest sources of energy in the near future. In this manner, this study serves as a reference for road construction and road network planning as well as a source of ideas for the development of intelligent traffic systems.