一种新型城市快速路网交通诱导系统的研发和应用

介绍了一种新型的基于可变信息标志(VMS)的网络级城市快速路交通诱导系统的设计方法。该系统是一个由“重要决策点图形式VMS”、“次要节点图文混合式VMS”、以及“地面一般道路VMS”三类VMS组成的VMS系统。文章在归纳VMS系统设计流程基础上,重点介绍了VMS的路网布局和功能设计、显示格式和显示技术的确定、VMS设立位置(前置距离)的确定、图形式VMS的面板设计和交通信息发布策略等关键技术,最后给出系统的应用实例,说明该新型交通诱导系统的应用效果。可供交通管理部门规划、设计城市快速路网交通诱导系统参考。     

旋转避障式打草割灌机的研究与应用

介绍了高速公路绿化养护中,如何实现打草割灌机械化作业的方式,及旋转避障式打草割灌机的研究和应用.     

浅谈高速公路社会公益性属性的发挥

对高速公路社会公益性属性的发挥进行了阐述.     

高速公路监控系统在冬季除雪、夏季防汛中的应用

高速公路的交通安全与天气状况有着密切的联系,做好冬季的除雪和夏季的防汛,不仅可以减少交通事故,也可以降低养护成本.从工作中的实际情况出发,阐述高速公路监控系统在冬季除雪、夏季防汛中的应用.     

沈大高速公路改扩建工程的生态环境保护措施

介绍了沈大高速公路改扩建工程中采取的生态环境保护措施:选择合理的建设方案减少对地表植被的破坏并避免产生沥青固体垃圾;采取了有效的工程措施减少水土流失;公路绿化和景观与周围环境相协调.     

轻型桥台计算的探讨

轻型桥台是高速公路小桥涵普遍使用的结构型式。采用两种计算模型,对钢筋混凝土轻型桥台的配筋进行比较计算,以了解两种模型的合理性,通过两种模型的偏心受压计算,验证了目前采用的桥台截面满足设计要求。     

浅谈高速公路灌缝施工工艺

介绍了高速公路对沥青混凝土路面裂缝修补所采用的几种方法、施工组织,并对几种方法进行比较,并得出了采用开槽修补法最适合高速公路灌缝施工。     

浅谈高速公路工程决算的编制

丹东至庄河高速公路是我省首个开展工程决算编制工作的高速公路项目,介绍了丹庄高速公路工程决算编制的工作流程和注意事项,为今后其他公路工程项目进行该项工作提供了有益的参考和借鉴。     

影响高速公路沥青路面平整度因素浅析

高等级公路对路面平整度要求较高,笔者通过铁四高速公路铁岭段的施工实践,分析了影响沥青路面平整度的六大因素,即混合料设计、摊铺基准面、摊铺、碾压等,从而为指导沥青路面施工、确保沥青路面平整度提供了参考.     

Effects of low speed limits on freeway traffic flow

Recent years have seen a renewed interest in Variable Speed Limit (VSL) strategies. New opportunities for VSL as a freeway metering mechanism or a homogenization scheme to reduce speed differences and lane changing maneuvers are being explored. This paper examines both the macroscopic and microscopic effects of different speed limits on a traffic stream, especially when adopting low speed limits. To that end, data from a VSL experiment carried out on a freeway in Spain are used. Data include vehicle counts, speeds and occupancy per lane, as well as lane changing rates for three days, each with a different fixed speed limit (80 km/h, 60 km/h, and 40 km/h). Results reveal some of the mechanisms through which VSL affects traffic performance, specifically the flow and speed distribution across lanes, as well as the ensuing lane changing maneuvers. It is confirmed that the lower the speed limit, the higher the occupancy to achieve a given flow. This result has been observed even for relatively high flows and low speed limits. For instance, a stable flow of 1942 veh/h/lane has been measured with the 40 km/h speed limit in force. The corresponding occupancy was 33%, doubling the typical occupancy for this flow in the absence of speed limits. This means that VSL strategies aiming to restrict the mainline flow on a freeway by using low speed limits will need to be applied carefully, avoiding conditions as the ones presented here, where speed limits have a reduced ability to limit flows. On the other hand, VSL strategies trying to get the most from the increased vehicle storage capacity of freeways under low speed limits might be rather promising. Additionally, results show that lower speed limits increase the speed differences across lanes for moderate demands. This, in turn, also increases the lane changing rate. This means that VSL strategies aiming to homogenize traffic and reduce lane changing activity might not be successful when adopting such low speed limits. In contrast, lower speed limits widen the range of flows under uniform lane flow distributions, so that, even for moderate to low demands, the under-utilization of any lane is avoided. These findings are useful for the development of better traffic models that are able to emulate these effects. Moreover, they are crucial for the implementation and assessment of VSL strategies and other traffic control algorithms.