Super Elevations :: physics science

gull you ever been driving down the road and approach a gambol too fast? What happens? You and the car belowgo centrifugal take and you as well as the car are pushed away from the turn, or up the grade also know as a superelevation. An engineer mustiness balance this force raising the grade on one perspective of the road. It should be noted that under theoretical observations steering would be daily but in order to provide these ideal conditions the clang component would be zero and the vehicle weight would balance the centrifugal force. In the real world we realize clash and good dealnot afford to frame the extremely steep slope of 30 every time we involve an off ramp or crosswise curve.In order for the means to comfortably maneuver a curve there are several(prenominal) variables that must be accounted for, the r of the curve, friction and velocity. Radius length may depend on sight distance and right of way, or place lines as well as sight distance. Friction depend s on the dig up properties of various materials and climate. The slope and velocity are usually dependent on the variables solely described. While building and designing these roads, it is industry standard to perplex 1/3 of the change in grade within the horizontal curve and 2/3 of the transition length on the tangent. In Laymans terms, by the time the car approaches the first deviate of the curve, 2/3 of the grade has already been built. This assures smooth transition for the driver to maneuver the curve.In order to get a split idea of what kind of friction coefficients are used in Alaska, we can look at the Badger Road Interchange construction roam on the Richardson Highway. The nortbound on ramp (from Badger Road) leave alone have a speed limit of35 mpha radius of 135 meters and a superelevation of 5.5%. From this data one may find the friction coefficient, () to be equal to 0.10. Another example taken from the same project, discovered from the off ramp in the south bou nd lane will have a radius of 253 meters, a super of 6% and a speed limit of45 mph was observed to be 0.09, which is just enough traction to make these corners at the posted limit. A friction coefficient that small leads the author to assume the engineers designed these turns to be taken under extremely slick conditions.