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<br />e <br /> <br />e <br /> <br />@ <br /> <br />64 <br /> <br />Chap. 4 I DESIGN AND REDESIGN OF NEIGHBORHOOD STREETS <br /> <br />Designing for the Appropriate Travel Speed <br /> <br />It is an internationally accepted rule that motorized traffic must drive slowly in residential <br />districts. An emergency stop at 35 mph [55 km/h] takes a stopping distance ranging from <br />115 to 165 feet [35 to 50 m] for an automobile. This distance is not acceptable so long as <br />drivers can be faced at any moment by children or pets playing or suddenly crossing the <br />road. <br />Moreover, research has shown that pedestrians are usuaU y not seriously injured when <br />hit by a car moving at a speed of less than 20 mph [30 km/h] at the time of impact. If im- <br />pact speeds are between 20 and 35 mph [30 and 55 km/h], injuries are usually serious, <br />while above 35 mph [55 km/h] they usually endanger life or are fatal. <br />Designers need to understand the relationship of their designs to travel behavior and <br />especially to the travel speeds of drivers, pedestrian circulation, and bicyclist behavior. An <br />activity diagram (Fig. 4.16) can show how different types of users will move through the <br />street space. The lines or cones of sight of motorists need to be drawn. Critical viewing <br /> <br />.--.-..--.. ---_._~-_._----~_...- .-----..------. - ..._._---~-,----------------_._--------------~--_.._--- <br /> <br /> <br />~,~ <br />Qr.\.~~~,~.. <br />. ~-:Q"J:' <br /> <br /> <br />'~-"'- <br />'-', <br /> <br />~ <br /> <br />Figure 4.16 Movement diagrams of various street users, their lines of sight. direction, and speed of movement. <br /> <br />"._..- ..--......,..--.. <br />