Traffic congestion, particularly in towns and on some main highways, is one of the main causes of energy over-consumption.
Whether in countries with a long tradition of motorized transport or in developing countries, chronic traffic jams have become a major issue in terms of energy consumption and emissions, polluting and greenhouse gases, particles, noise and loss of efficiency.
Stopping and starting combine two issues: using a thermal engine at low revs when its efficiency is at its lowest (between 5 and 10 %) and fighting the inertia of the vehicle. We use a considerable amount of energy just to move a few yards at a time*. Using a stop and start system, a hybrid vehicle or an electric vehicle only solves the first issue.
Improving traffic flow involves combining a large number of solutions. One of them is the creation of new public transport and road (including car parks) infrastructures. But these networks are not infinitely expandable, particularly in urban and semi-urban areas.
We cannot increase the area on the ground but we can try to reduce the area occupied by vehicles by producing smaller urban vehicles, reducing the number of vehicles simultaneously using a section of road by using public transport, carpooling, car-sharing, implementing hub and delivery management (the last mile) and avoiding traffic jams with real-time GPS guidance.
Many of these solutions have been around for a long time but ease of implementation varies from country to country. However, one set of solutions is proving popular throughout the world: Intelligent Transport Systems (ITS) which provide motorists with information about the traffic conditions in real time so they can optimize their route.
Welcome to the rapidly developing world of connected mobility.
* Approximate estimate of gasoline consumption of a 1.2-ton vehicle in a 1 km traffic jam stopping and starting every 5 m and accelerating from 0 to 15 km/h (4 m/s)
Kinetic energy = 0.5 x 1200 x 4 x4 = 9600 J = 2.67 Wh
Energy absorbed by the engine: 2.67/0.05 = 53 Wh
Number of stops and starts over 1 km: 1000/5 = 200 total energy of which 10.68 kWh is absorbed,
which is 1 liter of fuel per kilometer or… 100 l/100 km!!! It's a good job this is just a highly theoretical calculation...