英语翻译
The type of facility is critical .the existence of uninterrupted flow ,the presence of medians ,and other major facility type factors significantly affect flow characteristics and capacity.The development environment has also been found to affect the performance of two-lane roadways ,multilane highways ,and signalized intersections.
Lane and shoulder widths can have a significant impact on traffic flow .Narrow lanes cause vehicles to travel closer to each other laterally than most drivers would prefer .Motorists compensate by slowing down or observing larger longitudinal spacing for a given speed ,which effectively reduces capacity ,service flow rates ,or both .
Narrow shoulders and lateral obstructions have two important impacts .Many drivers will steer away from roadside or median objects they perceive to pose a hazard .This action brings them laterally closer to vehicles in adjacent lanes and cause the same reactions as those exhibited in narrow lanes .
Restricted design speeds affect operation and level of services ; drivers are forced to travel at somewhat reduced speeds and to be more vigilant in reacting to the harsher horizontal and vertical alignments resulting from a reduced design speed .In extreme case ,the capacity of multilane facilities has been found to be affected by low design speeds .
The horizontal and vertical alignment of a highway depends greatly on the design speed used and the topography through which the roadway must be constructed .Procedures for uninterrupted flow facilities categorize the general terrain of a highway as follow :