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21.
This paper presents a continuous approximation model for the period vehicle routing problem with service choice (PVRP-SC). The PVRP-SC is a variant of the period vehicle routing problem in which the visit frequency to nodes is a decision of the model. This variation can result in more efficient vehicle tours and/or greater service benefit to customers. We present a continuous approximation model to facilitate strategic and tactical planning of periodic distribution systems and evaluate the value of service choice. Further, results from the continuous model can provide guidelines for constructing solutions to the discrete PVRP-SC. 相似文献
22.
Karen Bryant Kane 《先进运输杂志》1997,31(2):215-231
During the summer of 1994 the Florida Department of Transportation hit the road seeking ideas and opinions from the state's citizens, businesses and visitors for developing a plan for Florida's future transportation system. Making a break from the past, the department decided to forego long-winded speeches, draft plans and maps too small to read in favor of more innovative approaches to public involvement. This paper details the development and implementation of the 2020 Florida Transportation Plan public outreach program, continued public involvement efforts and the lessons learned. 相似文献
23.
采用了3.5L 276bhp的丰田V6引擎,2+2座椅,GT水准的抛光处理,4.5万英镑的起售价。我们有机会独家目睹Lotus令人振奋的将来。有感染力的吼叫声在Lotus的Hethel总部四周回荡。全新的Lotus Evora距离首次公开还有两个星期的时间,团队非常自信他们达成了非凡的成绩。很显然,他们丝毫没有为世人将会对这个新生\"婴儿\"产生一定看法而感到焦虑。 相似文献
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ABSTRACT Cities are promoting bicycling for transportation as an antidote to increased traffic congestion, obesity and related health issues, and air pollution. However, both research and practice have been stalled by lack of data on bicycling volumes, safety, infrastructure, and public attitudes. New technologies such as GPS-enabled smartphones, crowdsourcing tools, and social media are changing the potential sources for bicycling data. However, many of the developments are coming from data science and it can be difficult evaluate the strengths and limitations of crowdsourced data. In this narrative review we provide an overview and critique of crowdsourced data that are being used to fill gaps and advance bicycling behaviour and safety knowledge. We assess crowdsourced data used to map ridership (fitness, bike share, and GPS/accelerometer data), assess safety (web-map tools), map infrastructure (OpenStreetMap), and track attitudes (social media). For each category of data, we discuss the challenges and opportunities they offer for researchers and practitioners. Fitness app data can be used to model spatial variation in bicycling ridership volumes, and GPS/accelerometer data offer new potential to characterise route choice and origin-destination of bicycling trips; however, working with these data requires a high level of training in data science. New sources of safety and near miss data can be used to address underreporting and increase predictive capacity but require grassroots promotion and are often best used when combined with official reports. Crowdsourced bicycling infrastructure data can be timely and facilitate comparisons across multiple cities; however, such data must be assessed for consistency in route type labels. Using social media, it is possible to track reactions to bicycle policy and infrastructure changes, yet linking attitudes expressed on social media platforms with broader populations is a challenge. New data present opportunities for improving our understanding of bicycling and supporting decision making towards transportation options that are healthy and safe for all. However, there are challenges, such as who has data access and how data crowdsourced tools are funded, protection of individual privacy, representativeness of data and impact of biased data on equity in decision making, and stakeholder capacity to use data given the requirement for advanced data science skills. If cities are to benefit from these new data, methodological developments and tools and training for end-users will need to track with the momentum of crowdsourced data. 相似文献