Influence of the Interchange Pattern Guide Sign on Running Speed in an Urban Complex Interchange

To analyze interchange guide signs' influence on vehicle speed in three kinds of interchange ramps of an urban expressway,vehicle operating data through a driving simulator experiment which was composed of twelve scenarios on basis of guide signs and different kinds of interchange ramps as two sorts of experiment controlling factors were obtained.The affected situation of speed kind indicators, "speed,standard deviation of speed,accelerator and standard deviation of accelerator",were analyzed through pair T test.The result of subjective questionnaires showed that 47.83%experimenters thought "interchange pattern guide sign" was the most effective among the system of interchange guide signs,and61.9%experimenters selected the running speed as the primary impacted factor,which was mostly reduced.Meanwhile,results of vehicle operating data indicated that under the effect of different levels of complex alignments of ramps, " interchange pattern guide sign" cooperated with three advanced guide signs had different influences on the speed kind indicators in three kinds of interchange ramps.In directional ramp,the speed indicators were not affected.But,in semi-direction ramp and loop ramp,the speed during affected range of "interchange pattern guide sign" was reduced significantly and the critical effected segments were mainly gathered in the vicinity of corresponding ramp exit.Nevertheless,speed indicators and critical affected segments influenced by "interchange pattern guide sign" were different in semi-direction ramp and loop ramp as a whole.What's more,the interaction effect between effects of "interchange pattern guide sign" and "three advanced guide signs" existed and was different in semidirection ramp and loop ramp.