Agenda - Council - 01/27/2004 - Laserfiche WebLink

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2000 ROAD DESIGN ~L~IN'UAL (ENGLISh) 5-4(3) COMBDOgD BY-PASS LA~'q'E A.PCD RIGHT-TURN LgxN-E (To be used only where cross street volume is Iow) Figure 5-4.01B 5--1.01.06 Median Acceleration Lane Minnesota highways have a limited number of median acceleration lanes. Those which have been constructed thus far have favorable results. At unsignglized intersections with relatively heaw truck volumes, the median acceleration lane provides the left turning truck, entering the expressway, the opportunity to accelerate and reduce the speed differential before enter/nc-the traffic stream. Median acceleration lanes should not be constructed indiscriminately, They may be used at locations where them is a high number of trucks turning left onto the ma/nlme, where the existing median does not provide enough room for a truck to stop in the median when malcng a two-stage crossing, and where there is a history of _ high Fate of truck accidents.. The basic design for a median acceieration lane is shown in Figure 5~.01C, the applied design criteria 1. The entenng throat should be wide enough so that a taming truck will be far enough from the through-lane not to have a negative Lmpact on the th.rough-lane traffic. 2. The tune width should be wide enough to provide the accelerating truck added buger in the zone where the speed differential is the contest. 3. There should be sufficient length for the truck to accelerate and reduce the speed differential before entering the through-tune. 4. ~b. en near a crossover, the acceleratiort lane taper shall end before the crossover lea-mm lane is developed. In 1997, the 87.5 percentile mass/power ratio for trucks was 192 lb/bp. The rate of acceleration from a stop for these trucks is 0.98 ftys: (ITE's 1999 Traffic Engmeemng t-I,,mdbook). Designers may use the appropriate acceieratmn rate for their design truck. The Formula used to calculate speed is: