Research On Safety Support And Economy Evaluation Of Superhighway

Highway plays an important role in China’s social and economic development,but as time goes on,the development of automobile technology puts forward new demands for the construction of highway.The highest design speed of 120km/h for road of grade I,first appeared in The Highhway Engineering Design Guidelines(Draft),published in 1951.More than sixty years have passed,vehicle performance and road design and construction technology have been greatly improved,and the Superhighway with higher design speed will be possible.At present,there has been a trend of improving the speed limit of highway.For example,the highway speed limit is 129km/h(80mile/h)in U.S.The highway speed limit is 130km/h in France,Switzerland and Austria.Italy raised the maximum speed limit to 140km/h.There is even no speed limit in Germany on part of the highway.The research related to Superhighway design speed more than 120km/h in China is still a blank,the related research abroad is also less and less.Therefore,this paper puts forward the research on the safety and economy of the Superhighway,which provides the basis for the construction of the expressway in the future.Based on the analysis of the definition and classification of road and highway,put forward the definition and classification of Superhighway,analyzed the driving characteristics,and calculated the capacity of Superhighway.Superhighway capacity research shows that the capacity of Superhighway for traditional single car increases with the increase of vehicle speed.And reaches the highest value when the speed is between 60km/h and 80km/h.As the speed continues to improve,the capacity gradually decreased.If capacity of Superhighway calculated by the way of auto train,the capacity is proportional to the speed.The capacity is 8 times as traditional,when the design speed is 180km/h.This paper analyzed the present situation of global traffic safety.Although the population and vehicles are increasing in the world,the traffic accidents and deaths gradually stabilized.It shows that the traffic safety measures achieved remarkable results.This paper analyzes the influence factors of traffic safety,including the factors of "person","car" and "road".People’s sense of traffic safety,vehicle technical support and highway technical support are demonstrated for the traffic safety.The results show that superhighway safety can be guaranteed,through improving the traffic safety awareness of "people",and improving the technical standards of roads and vehicles.This paper analyzed the influence of the road horizontal alignment,longitudinal section and cross section alignment on traffic safety.Based on the theory of linear design of general highway,referenced railway line design theory,studied the design theory of horizontal alignment,longitudinal section and cross section alignment of Superhighway,and laid a foundation for safety design of Superhighway.The horizontal alignment design theory research includes the contents of the horizontal alignment;the length limit of straight line,the circle curve radius determination and the length of the transition curve.The longitudinal section design theory research includes the restriction of the longitudinal gradient,the limitation of the length of the longitudinal slope and the determination of the parameters of the vertical curve of the Superhighway.The cross section design theory research includes the component of the cross section and the width of the lane.This paper analyzed the fuel consumption economical efficiency of vehicle,including fuel economical efficiency evaluation index,fuel consumption equation and economic characteristic curve,ways to improve vehicle fuel economical efficiency,the test method to determinate the vehicle fuel consumption economical efficiency.The vehicle fuel consumption was forecasted with SPSS when the speed was higher than 120km/h,and the basic data of vehicle fuel consumption came from road test of real vehicle and "BITAUTO test".The forecasted results show that,when the speed was 140km/h,160km/h and 180km/h,the fuel consumption was 1.30times,1.74 times and 2.09 times as much as the fuel consumption when it run at the speed of 120km/h.Based on the analysis of the construction cost of the general highway and the High-speed railway,the paper estimated the cost of the Superhighway.Based on the cost estimation of the Superhighway,referenced the construction cost and the toll collection standard of the general highway,and determined the toll collection standards of the Superhighway.According to the toll collection standards and the forecast of fuel consumption costs,calculated the cost to use the Superhighway by single vehicle and single person.Based on the cost analysis of road passenger transport,railway passenger transport and air passenger transport,the paper calculated and compared the single person cost of per kilometer by the above trip mode.The results show that the Superhighway travel cost(from ￥0.29 to 0.47/km)is higher than road passenger transport(￥0.28/km),general highway driving(￥0.18/km),and express train travel(￥0.23/km),but lower than high speed railway first class seat(￥0.78/km),and far below the business class(￥2.42/km)and economy class(￥0.92/km)of air passenger travel,so the Superhighway has certain advantages in economy efficiency.Through the Superhighway safety and economy analysis above,Superhighway construction has certain feasibility.Superhighway of grade one,superhighway of grade two and superhighway of grade three respectively is expected in 15 years,30years and 40to 50years into the engineering practice.