An intelligent transportation system (ITS) is an advanced application which aims to provide innovative services relating to different modes of transport and traffic management and enable users to be better informed and make safer, more coordinated, and 'smarter' use of transport networks.

Some of these technologies include calling for emergency services when an accident occurs, using cameras to enforce traffic laws or signs that mark speed limit changes depending on conditions. Although ITS may refer to all modes of transport, the directive of the European Union 2010/40/EU, made on July 7, 2010, defined ITS as systems in which information and communication technologies are applied in the field of road transport, including infrastructure, vehicles and users, and in traffic management and mobility management, as well as for interfaces with other modes of transport.

ITS may be used to improve the efficiency and safety of transport in several situations, i.e., road transport, traffic management, mobility, etc. ITS technology is being adopted across the world to increase capacity of busy roads and reduce journey times.

Commercially available applications include:

• Adaptive Cruise Control (ACC) automatically adjusts vehicle speed to maintain a safe distance from vehicles ahead.
• Eco-driving systems involve either providing real-time feedback to the driver or partially controlling the vehicle's speed to save fuel and reduce emissions.
• Eco Cruise Control (ECC) adjusts vehicle speed according to topography.
• Intelligent Speed Adaptation (ISA) automatically adjusts vehicle speed to stay within legal speed limits and alerts drivers in case of excess speed.

Applications that have not yet made it to market, either due to developmental technology or adequate policy frameworks:

• Collaborative ACC (CACC) uses vehicle-to-vehicle (V2V) communication to co-ordinate smoother driving on highways. Vehicles form platoons for long distances on motorways benefitting from co-ordination and aerodynamic efficiency.
• Eco Approach and Departure (EAD) broadcasts Signal Phase and Timing (SPaT) information to avoid idling and unnecessary acceleration at intersections.
• Autonomous Vehicles (AVs) that fully automate all of the above approaches.

Autonomous vehicles may increase vehicle activity due to both induced demand and a potential diversion from low-carbon modes. Intermediate technologies could have similar effects. Increased vehicle automation should go hand-in-hand with demand management measures to reduce adverse rebound effects. Demand management helps keep travel activity in check and ensure it is covered by the most efficient modes of transport. The transition to LZEVs reliant on low-emission energy pathways should also accompany smooth driving measures. Variable Speed Limits (VSL) attempt to moderate traffic via roadside displays without in-vehicle devices. Research is not conclusive as to whether VSL effectively reduces emissions.