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Stopping Sight Distance <br />4 Stopping sight distance (SSD) is the distance covered by a vehicle <br />during a stopping procedure. SSD should be provided at all pedes- <br />trian crossings. <br />• The SSD considers both brake reaction distance and braking dis- <br />tance. <br />SSD <br />1.47St <br />s2 <br />+ 1.075 it a <br />30 <br />R32.2 <br />Where: <br />SSD = stopping sight distance <br />S= speed (mph) <br />t — brake reaction distance, 2.5 s <br />a deceleration rate, ft/s2, default 1.1.2 ft/s2 <br />G — grade, rise/run, ft/ft <br />For more information on SSD, please see the AASHTO Green Book. <br />Pedestrian Sight Distance <br />• While Minnesota State Statute requires that motorists stop for pe- <br />destrians legally crossing, many pedestrians wait for an adequate <br />gap in traffic before crossing. <br />• Pedestrian sight distance (PedSD) is a term to describe the dis- <br />tance covered by a motorist during the time it takes a pedestrian to <br />recognize an adequate gap in traffic and cross the roadway. <br />PedSD =1.47S <br />Where: <br />PedSD = pedestrian crossing sight distance <br />S = design speed (mph) <br />L = crossing distance (ft) <br />S = average pedestrian walking speed (ft(s), <br />default = 3.5 ft/s <br />= pedestrian start-up and end clearance time (s), <br />default = 3,0 s <br />Traffic and Pedestrian Data <br />• The volume of vehicles on the roadway directly affects the number <br />of gaps available for pedestrians to cross a roadway. <br />The volume of pedestrians using the crossing affects how motor- <br />ists view the crossing. A highly used crossing may be more recog- <br />nizable to a motorist, resulting in a safer crossing. <br />10 <br />