below Y min N S Y Determine the minimum required length in s of the yellow interval for each approach Assume the average vehicle length is 20 ft and the perception reaction time d is 1 0 s Use the deceleration rate of 11 2 ft s recommended by AASHTO 4 6454 min Median width ft Number of 12 ft lanes on each approach E W Design speed mi h Grade N S Approaches 16 2 40 0 E W Approaches 12 1 35 4 Determine for how long you will provide the yellow interval Your response is within 10 of the correct value This may be due to roundoff error or you could have a mistake in your calculation Carry out all intermediate results to at least four digit accuracy to minimize roundoff error s 3 3154 X Your response differs from the correct answer by more than 10 Double check your calculations s