Question

An freeway escape ramp is designed in three gradients:The first section is designed with the same materials as mainline concrete freeway with 300ft at a grade of 6%. The second section and the third sections are designed with 12% upgrade. The second section is 550 ft pea gravel while the last section is sand. Determine the last section length

Answer 1

and 0.010 The AASHTO Geruch Book states that an escape samp should be designed entory speed of somph, a gumph design speed being prefeared. where the grade may change within the bed, the final velocity at the end of the first grace may be calculated and used as the initial velocity (vi) for the next section, and so on. The formula is: values of R 10 Diffeurt Materials v² vit - 30L(RIG) Suchacing Material 'R' value Fel Beiand section : P.cc v? 90°- 308550 (0.350+0.12) Asphalt concocte 0.012 [ 44.65mph Geravel cempoded 0.015 For last section : Earth, sandy, loose 0.037 v? 44.65 30x L (0-1570-12) Gushed aggregate, d.oso loose Geravel, loose 0-100 Sand 0.150 Pea gravel 0-250 [V. (1993-62-8-12

For Ramp kength: support La v² ou and a 301 RtG) and din t between where, Ldistance to stop (ft). = entering velocity (mph) G: Peacent grade divided by 100 Re Jelling desistance L= (44-64-2.84 [² Tripom 30(0.15 +0.12) -) L= (44:64) +62-8412)? 2 (1464)82-892) 81 - 8.12 - 1992-72 +8.06L-253.55V 0.04L+853-5523 1992-72 = 1 = 61.6lft the weight 2