Road network is a critical component of public infrastructure,and the supporting system of social and economic development.Based on a modified kernel density estimate(KDE)algorithm,this study evaluated the road servic...Road network is a critical component of public infrastructure,and the supporting system of social and economic development.Based on a modified kernel density estimate(KDE)algorithm,this study evaluated the road service capacity provided by a road network composed of multi-level roads(i.e.national,provincial,county and rural roads),by taking account of the differences of effect extent and intensity for roads of different levels.Summarized at town scale,the population burden and the annual rural economic income of unit road service capacity were used as the surrogates of social and economic demands for road service.This method was applied to the road network of the Three Parallel River Region,the northwestern Yunnan Province,China to evaluate the development of road network in this region.In results,the total road length of this region in 2005 was 3.70×104km,and the length ratio between national,provincial,county and rural roads was 1∶2∶8∶47.From 1989 to 2005,the regional road service capacity increased by 13.1%,of which the contributions from the national,provincial,county and rural roads were 11.1%,19.4%,22.6%,and 67.8%,respectively,revealing the effect of′All Village Accessible′policy of road development in the mountainous regions in the last decade.The spatial patterns of population burden and economic requirement of unit road service suggested that the areas farther away from the national and provincial roads have higher road development priority(RDP).Based on the modified KDE model and the framework of RDP evaluation,this study provided a useful approach for developing an optimal plan of road development at regional scale.展开更多
Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and ...Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and in the case of great variation of rock properties. Not having a previous experience in the seismic design of the tunnels that pass through tectonic zones with very large heterogeneity （strong rock-soil or very poor rock that behaves like soil） this article presents the general aspects of seismic calculation of tunnels and application in a specific example. The article presents the methods of seismic input modeling, design and particularities of numerical calculations. The geological conditions in which the case study tunnel will be constructed are very common in Albanian territory and represent one of the most difficult cases for the construction of road tunnels. The applied approach for using the longitudinal models for generating time histories of acceleration that can be used as input for transversal models is very simple and will help the designers for the seismic analysis of other tunnels that will be constructed in Albania.展开更多
Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoi...Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoises Gopherus polyphemus in scrub habitat in central Florida, as evidenced by the tracks left by tortoises on sand roads. Tortoises （and most other taxa leaving tracks on the roads） did not appear to make use of roads for travel but attempted to cross them, the success of which was influ- enced by the size of the individual. Smaller animals （presumably younger tortoises） were more challenged than larger animals by both sand road widths and depths of vehicle ruts in sand roads. Sand roads may present both physical and physiological challenges to gopher tortoises, particularly to small ones. This research provides further evidence that the negative influence of roads in fragmenting the environment is not limited to vehicle mortality [Current Zoology 61 （4）： 578-585, 2015].展开更多
基金Under the auspices of National Natural Science Foundation of China(No.41371190,31021001)Scientific and Tech-nical Projects of Western China Transportation Construction,Ministry of Transport of China(No.2008-318-799-17)
文摘Road network is a critical component of public infrastructure,and the supporting system of social and economic development.Based on a modified kernel density estimate(KDE)algorithm,this study evaluated the road service capacity provided by a road network composed of multi-level roads(i.e.national,provincial,county and rural roads),by taking account of the differences of effect extent and intensity for roads of different levels.Summarized at town scale,the population burden and the annual rural economic income of unit road service capacity were used as the surrogates of social and economic demands for road service.This method was applied to the road network of the Three Parallel River Region,the northwestern Yunnan Province,China to evaluate the development of road network in this region.In results,the total road length of this region in 2005 was 3.70×104km,and the length ratio between national,provincial,county and rural roads was 1∶2∶8∶47.From 1989 to 2005,the regional road service capacity increased by 13.1%,of which the contributions from the national,provincial,county and rural roads were 11.1%,19.4%,22.6%,and 67.8%,respectively,revealing the effect of′All Village Accessible′policy of road development in the mountainous regions in the last decade.The spatial patterns of population burden and economic requirement of unit road service suggested that the areas farther away from the national and provincial roads have higher road development priority(RDP).Based on the modified KDE model and the framework of RDP evaluation,this study provided a useful approach for developing an optimal plan of road development at regional scale.
文摘Recently based in the performance of tunnels under seismic movements a good progress is made in the seismic design of tunnels. The majority of problems in the tunnel structures take place in near fault conditions and in the case of great variation of rock properties. Not having a previous experience in the seismic design of the tunnels that pass through tectonic zones with very large heterogeneity （strong rock-soil or very poor rock that behaves like soil） this article presents the general aspects of seismic calculation of tunnels and application in a specific example. The article presents the methods of seismic input modeling, design and particularities of numerical calculations. The geological conditions in which the case study tunnel will be constructed are very common in Albanian territory and represent one of the most difficult cases for the construction of road tunnels. The applied approach for using the longitudinal models for generating time histories of acceleration that can be used as input for transversal models is very simple and will help the designers for the seismic analysis of other tunnels that will be constructed in Albania.
文摘Roads affect wildlife significantly through direct mortality but also through behavioral change. We explored the ef- fects of unsurfaced sand roads with a low traffic volume on the travelling behavior of gopher tortoises Gopherus polyphemus in scrub habitat in central Florida, as evidenced by the tracks left by tortoises on sand roads. Tortoises （and most other taxa leaving tracks on the roads） did not appear to make use of roads for travel but attempted to cross them, the success of which was influ- enced by the size of the individual. Smaller animals （presumably younger tortoises） were more challenged than larger animals by both sand road widths and depths of vehicle ruts in sand roads. Sand roads may present both physical and physiological challenges to gopher tortoises, particularly to small ones. This research provides further evidence that the negative influence of roads in fragmenting the environment is not limited to vehicle mortality [Current Zoology 61 （4）： 578-585, 2015].
