14 DAY TRIAL // Scientists at the University of Hartford in the United States believe they may have just found a very effective way of “calming” the city's traffic and, implicitly, its jams. They are using a statistical theorem published by the famed mathematician Thomas Bayes (1702-1761), which deals with assessing the outcome of events that cannot be covered by conventional statistic methods. In the models the experts have used, they have noticed that implementing a range of changes based on the 18th century theorem has led to a drastic decrease in the number of overall accidents on the city roads.
That is to say, they haven't noticed a significant reduction in the number of crashes on streets that registered a small number before the test has been conducted. However, on some of the larger ones, where more collisions took place in the “before” stage of the study, the measures employed by the experts have proven to drastically reduce the number of overall crashes. This has been achieved through a number of systems that have been installed throughout the city.
Among these, UH Department of Civil Engineering expert Clara Fang and Urban Engineers, Inc. specialists Joseph Rimiller and Najib Habesch have mentioned mini-roundabouts, curb extensions, bicycle lanes, parking chicanes, speed tables, and also road “diets.” The latter concept simply refers to removing excess lanes from certain avenues. A lack of too much space significantly decreases the average speed on those specific roads, reducing the number of recorded accidents.
According to the experts behind the new study, Bayes' theorem can be summarized as follows: “The probability of any event is the ratio between the value at which an expectation depending on the happening of the event ought to be computed, and the value of the thing expected upon its happening.” Basically, for their investigation, the experts have used this empirical theorem to predict the expected crash rates on all the roads that have been part of the study.
“Speeds at the study sites were reduced by up to six miles per hour, with an average reduction of three to four miles per hour. The road diets also prevented aggressive drivers from passing more prudent drivers, thus, eliminating one potential source of conflict,” the conclusion of their paper says.