Speed Limit Research Of Extra-long Road Tunnel Based On Traffic Efficiency And Safety

Rapid development of motor vehicles over past three decades has impressed great pressure on existing traffic environment.It is urgent for traffic managers to seek methods that could be used to eliminate increasingly severe contradiction between traffic requirement and supplement.Reasonable traffic infrastructure construction and planning can be seen as the most effective and direct way that could relieve the pressure of existing traffic system.Tunnels could break through the limitation of natural environment and have less negative influence on existing traffic condition which may account for the increasing use of it in recent years.Additionally,there is no relevant standard,specification or handbook that could be referenced by traffic managers to formulate speed limit in tunnels.Increasingly number of traffic accidents happened in road tunnels especially those in extra-long tunnels calls for specific and reliable standard.The crux of management of road tunnels is to establish a reasonable speed limit scheme according to driving environment,traffic safety and efficiency.This paper will present a speed limit model based on improved Euclidean Metric to research the most suitable speed limit scheme of Shenzhen Maluan Tunnel.Firstly,traffic safety model will be constructed by using negative binomial model.The data sample comes from tunnels in Norway from 2001 to 2006.Secondly,after analyzing characteristics of traffic flow in Maluan Tunnel,travel efficiency model would be constructed.Benefits of traffic managers and users are both considered in this model.Speed limit model could be finally modeled by choosing a suitable weighting coefficient between traffic safety and travel efficiency to improve Euclidean Metric.Lastly,the optimal speed limit scheme of different traffic condition can be derived by the solving speed model.Simulation of different speed limit scheme(optimal speed limit of the model,60km/h and 80km/h)will be conducted for the purposed of evaluating the advantages of the model presented in this paper.It can be found that the control effect of optimal speed limit scheme under abnormal traffic condition is much better than normal traffic condition.