(1992): (1) a 2-ft positive offset provides unrestricted sight distance when the opposite left-turn vehicle is a passenger car, and (2) a 3.5-ft positive offset provides unrestricted sight distance when the opposite left-turn vehicle is a truck, for design speeds up to 70 mph. Subjects' reaction times to recognize the color of the "on" signal were measured, as was the accuracy of response. The survey included 200 different scenarios, of which 68 contained protected left-turn indications. Some of these operations are done simultaneously by many drivers, and some operations, such as shifting gears, may be done before searching for intersecting traffic or may not be required with automatic transmissions. Staplin, et al. In the study, pedestrian-vehicle conflicts were observed during a baseline period, where the signal phasings at each intersection provided the onset of the pedestrian WALK signal and the onset of the green signal for turning vehicles concurrently. It was therefore recommended that the supplemental message WHEN PEDESTRIANS ARE PRESENT be added to theMUTCDas an accepted message that may be used with an NTOR sign when right-turn volume is light to moderate and pedestrian volumes are light or occur primarily during intermittent periods, such as in school zones. There was no significant interaction between font and material, however. Generally, safety benefits are related to the reduced speed in the roundabouts, the simplification of conflict points, and the "increased responsibility caused by the slower motion and the need to concentrate and yield, as compared to driver behavior in signalized intersections" (Jacquemart, 1998). The countermeasures were developed using input from focus groups conducted with aging drivers in an earlier phase of the study. Stopping sight distance is measured from the driver's eyes, which is 3.5 feet above the pavement surface, to an object 2 feet high on the road. Studies in other countries help to shed some light on the optimum design characteristics of modern roundabouts. The participants gave slightly better ratings, although still worse than continental or bar pairs markings, for transverse markings during the nighttime as compared to the daytime. At the conclusion of this research, the authors recommended a reduction in the design walking speed from 4.0 ft/s to 3.0 ft/s at locations where there is significant usage by aging pedestrians.