Physics of the Yellow Change Interval ITE International Convention, 8/3/2015 1 ππππ π = ππ + ππ 2 ππππ π = ππ + ππ 3 ππ π= π 4 Critical Point, Comfortable Stopping Distance, Braking Point End of Perception-Reaction Time Must Stop E B C Must Go πππ ππ ππ π π π 5 β For the ITE yellow change interval formula to work, how fast must you go to make it to the intersection before the light turns red? β π«πππππππ = π»πππ πΊππππ ππ ππ + ππ ππ π ππ = ππ + ππ ππ 6 For the ITE yellow change interval formula to work . . . β’ You must go the maximum allowable speed or faster from the critical point to the intersection entry point. β’ Slowing down is forbidden. β’ Which is the reason why people beat the light. β’ You must know exactly where the critical point is. 7 ITE Yellow Change Interval Equation works only for UNIMPEDED THROUGH-MOVEMENTS 8 ITE Yellow Change Interval Equation SHORTS THE YELLOW for UNIMPEDED TURNING-MOVEMENTS IMPEDED MOVEMENTS 9 General Form of a βStandardβ Yellow Change Interval Equation ππππ = π ππππ 10 What is the equation for a turning vehicle that slows down with constant deceleration from the maximum allowable speed ππ at the critical point to the to ππ at the intersection? 11 What is the equation for a turning vehicle that slows down with constant deceleration from the maximum allowable speed ππ at the critical point to the to ππ at the intersection? ππππ π = (ππ + ππ )/π 12 What is the equation for impeded movements and U-turns? ππππ ππ = ππ + π 13 What else should ITE take from the physics tool box? 1.Engineering Tolerances for purposes of law enforcement 2.Acceptance of only Physical Solutions. Only physical solutions are engineering practices. β’ Not Stochastic Solutions β’ Not Analytic Solutions β’ Not Misapplications of Physics 14
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