Since the 18th century, mechanization has enabled each mode of transportation to evolve its motive power and vehicles. New engine technologies can be used across several modes with specific adaptations. The first and most meaningful innovation was the steam engine, which improved the performance of maritime and railway transport from the end of the 18th century into the 19th century. The bulk of a steam engine made it impractical for road transportation.
The internal combustion engine (ICE) in the late 19th century brought large-scale mechanization of transportation, especially road transport. It was followed by the diffusion of cars, buses, and trucks supported by the construction of vast highway networks. For rail, diesel locomotives replaced steam engines, improving power and range. However, high-speed rail (HSR) development relied on electric motors due to their ability to generate velocities that internal combustion engines could not.
For air transport, the internal combustion engine (piston engine) allowed heavier planes and the emergence of the first commercial services in the 1920s. Innovations in air propulsion led to jet planes that could quickly transport a large number of passengers over long distances. Then, wide-body jets (such as the B747) further improved the scale at which air transportation could carry passengers and freight.
The technological evolution of maritime transportation impacted the conveyances more substantially than their speed, particularly their economies of scale. Metallic hulls and fuel propulsion enabled the growth of ship size as well as their specialization (oil, freight, containers). The introduction of containerships in the 1970s allowed a versatile cargo carrier that benefited from economies of scale and supported the rapid development of the global economy.
In the 21st century, the automation of transport systems, including their terminals, is unfolding. This improves their reliability and performance while reducing their operating costs. Self-driving vehicles and drones are being introduced.