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Along with the rapid development of national economy, the construction of highways constantly accelerates. But because of constraints from social economic level, technical level and political factors, on early stages of highway construction, the great majority of highway which have been built and used are two-way four lanes which can not adapt to the growth of traffic volume and the demand of social development already, so it is necessary to expand traffic capacity of the old road. If construct a new road near the old road, that make a larger investment scale and occupy more land, widen the old road is a better way because it can shorten the construction period and achieve good economic and social benefits.In order to broaden the old road change the emergency parking lane into a running lane, affected by the vehicle parking on the side lane and the safe distance which is become narrower, the capacity of the side lane should become reduce, so the capacity of all the lanes can not reach the desired level, the size and the pacing of the emergency parking bay can affect the capacity and the safety of the road. This paper takes the Q-Y Highway for example, study the key technology of road expansion deeply, research the follow contents:First, describes the operation characteristics of highway basic sections systematically, considering the characteristics of the renovation and widening roads, analysis the traffic flow characteristics of parking on the roadside and the emergency parking bay.Second, collect basic information about the Q-Y Highway through reliable means, set the parameters of micro-simulation, analyzing the different layout options on the impact of road capacity. Further, use SPSS software to obtain the relationship equation of the pacing of the emergency parking bay and the largest capacity of the road.Next, on the basis of full analysis on the road safety level in the demand, determine the safety evaluation index system, analysis of different programs on the expansion level of road safety by using evaluation index.Finally, follow the principles of economic rationality, take the maximum capacity and maximum safety level as the dual objective, to determine the final road expansion programs, evaluated the final project by comparing the road capacity and quantities and other aspects.
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