This article reports on new techniques being developed to spot, predict, and help drivers avoid traffic jams. Systems such as the Traffic Message Channel and the Vehicle Information and Communication System (VICS), in Europe and Japan respectively, pipe data from traffic centres into in-car navigation systems via FM radio signals. Meanwhile ITIS, a British company, is one of several firms experimenting with mobile-phone signals to monitor traffic on roads that lack sensors or cameras. In Redmond, Washington, at the headquarters of Microsoft, employees have been testing a traffic-prediction system called JamBayes. Users register their route preferences and then receive alerts, by e-mail or text message, warning them of impending gridlock. JamBayes uses a technique called Bayesian modelling to combine real-time traffic data with historical trends, weather information and a list of calendar events such as holidays.