Today, however, after increasing in sophistication for almost 150 years, the traffic signal is once again losing the battle against congestion. The average American spends 38 hours a year stuck in traffic, thumping the wheel as the fumes rise. Drivers in the Los Angeles-Long Beach-Santa Ana region experience the worse delays in America, according to a study quoted in the Los Angeles Times, adding up 81 hours idling on freeways in 2015.
The Centre for Economics and Business Research estimates US commuters will waste about $180bn a year by 2030 in lost time and increased fuel and business costs.
The good news is that a revolution in traffic-light technology is underway. Smart traffic lights, enhanced with artificial intelligence and linked via the cloud, will start to chatter among themselves – and with connected vehicles and other sources – to maximise traffic flow and cut accidents, pollution and the pulse-raising pain of traffic jams.
Real-time traffic signals
A ride through the relatively traffic light-free streets of Utah offers a glimpse into the future. Most town planners in America analyse historical data, predict traffic flows and set light sequences every few years. Controllers at the Utah Department of Transportation (UDOT), in sharp contrast, can use a fibre-optic network connecting 1,000 cameras to adjust the majority of its traffic lights within 30 seconds.
Utah has the advantage of a modern – and expensive – infrastructure designed to cope with traffic for the 2002 Winter Olympics. A more cost-effective solution is being trialled in Pittsburgh where a network of smart traffic lights is being installed. Instead of using humans to monitor and react to traffic flow, they use radar sensors and cameras to detect traffic and sophisticated algorithms to make real-time signal adjustments.
A Pittsburgh pilot scheme involving nine smart signals in 2012 cut travel time by 25 per cent and vehicle emissions by 20 per cent. “Each intersection builds a plan that optimises local traffic flow,” Stephen Smith, a professor at the Robotics Institute at Carnegie Mellon University in Pittsburgh, told CityLab, a website dedicated to thinking about cities of the future. “Once it does that, it communicates its outflows to its downstream neighbours.”