Risk to Bicyclists in a Separated Path from Left Turns across Multiple Lanes: A Case for Protected-Only Left Turns

At signalized intersections, permitted left turns (i.e., on a green ball, after yielding) across multiple through lanes and across a separated bike lane or bike path present a threat to bicyclist safety. A conflict study of two such intersections with a bidirectional bike path found that when cyclists cross while a vehicle is ready to turn left and there is no opposing through traffic to block it, the chance of the left-turning motorist yielding safely was only 9%, and the chance of their yielding at all—including yielding only after beginning the turn, then stopping in the opposing through lanes—was still only 37%. Motorist non-yielding rates were worse toward bikes arriving during green, toward bikes approaching from the opposite direction (i.e., riding on the right side of the road), and toward bikes facing a queue with multiple left turning vehicles. Of 112 cyclists who arrived on green when there was at least one left-turning car, but no opposing through traffic blocking it, 73 had to slow or stop to avoid a collision. Although these conflicts could be essentially eliminated using protected-only left turn phasing (turn on green arrow), common existing criteria prefer permitted left turns to reduce vehicular delay. A case study shows how, by considering multiple signalization alternatives, it can be possible to convert left turns to protected-only phasing without imposing a substantial delay burden on vehicles or other road users.

The transition process towards the yellow ball in tennis teaching

More than 10 years have gone by since Play and Stay campaign was launched, and even today, there is a lack of scientific studies focusing their strategies on the transition process between the stages that make up Tennis 10s. So, on the basis of interviews with expert coordinators, who are responsible for sport initiation programmes in Brazilian clubs, this study tries to describe the strategies used for the transition between the “green ball” and the “yellow ball”.