Platooning on two-lane two-way highways: An empirical investigation

This paper presents an empirical investigation into platooning on two-lane two-way highways. The main objective is to better understand this phenomenon that has important implications on traffic performance and safety. Field data from three study sites in the state of Montana were used in this study. Separate investigations were performed to examine the relationships among platoon-related variables, namely; time headway, travel speed, and platoon size. The study confirmed that interaction between successive vehicles in the traffic stream generally diminishes beyond a time headway threshold value that fell in the range of 5–7 seconds. Also, the study revealed that very short headways (less than one second) are more associated with aggressive driving and higher speeds than with slow-moving platoons due to lack of passing opportunities. Further, the study found that amount of impedance to traffic is proportional to the size of platoon as evidenced by the relative difference between mean speed of various size platoons and the mean speed of unimpeded vehicles. The study provided other valuable insights into the platooning phenomenon on two-lane highways that are essential in developing a better understanding of traffic operation on two-lane highways.     

Past,present, and future of the satellite-based automatic identification system: areas of applications (2004–2016)

In 2016, the world shipping fleet grew by 3.5%. Even if the annual growth rate remains at its lowest since 2013, the global situation is still in overcapacity (UNCTAD 2016). Ninety percent of global trade, by volume, is done by sea. Monitoring this fleet helps with vessel navigation, informing to help avoid critical situations such as collisions, accidents leading to oil pollution, grounding, or ships in distress, but also because traffic management in congested areas is essential. For system wide management, in regions such as MPAs (marine protected areas), conservation is the key factor, and movements can be monitored and analyzed in order to determine illegal or suspicious activities, or in order to limit and/or divert traffic, to mitigate the risks to species subject to protection. It is among these efforts that the automatic identification system (AIS) can play a key role. Since 2004, this VHF transceiver-based reporting system, imposed by the International Maritime Organization (IMO), has shifted from a traditional vessel identification device to a tool used in a wide variety of applications. The most common uses are safety and security; these issues are quite visible in the media and may touch more people on a global scale (e.g., piracy, oil spills). Over the years, AIS has become, especially with the emergence of the satellite-based capture of the signal in 2011, a widely used tool for developing applications such as fisheries monitoring, marine conservation, air pollution forecasting and modeling, ballast water monitoring, invasive species transport, and many more. In this paper, we propose to review the peer-reviewed publications related to the uses and applications of the AIS.     

Exploring partnership between transit agency and shared mobility company: an incentive program for app-based carpooling

Transportation - How should public transit agencies deliver mobility services in the era of shared mobility? Previous literature recommends that transit agencies actively build partnerships with...     

Towed-Diver Surveys,a Method for Mesoscale Spatial Assessment of Benthic Reef Habitat: A Case Study at Midway Atoll in the Hawaiian Archipelago

An integrated method for benthic habitat assessment is described, in which divers maneuver boards equipped with digital video, temperature, and depth recorders while being towed behind a small boat. The tow path is concurrently recorded by a GPS receiver, and a layback model is applied to more accurately map the data. Percent cover of salient benthic categories is quantified by whole-image analysis of still frames sampled at 30-s intervals. The results of 15 towed-diver surveys at Midway Atoll in the Hawaiian Archipelago during a mass coral bleaching event are presented to exemplify the method and are compared to results derived from conventional methods. Towed-diver surveys bridge a gap between large-scale mapping efforts using satellite data and small-scale, roving diver assessments, providing a mesoscale spatial assessment of reef habitats. The spatial coverage of towed-diver surveys provides comprehensive data to managers concerning the extent, intensity, differential taxonomic response, and bathymetric correlates of bleaching.     

Institutional and Conceptual Barriers to Climate Change Adaptation for Coastal Cultural Heritage

Climate change is increasing the speed at which tangible coastal cultural heritage is changing in character or being lost through weathering, erosion, and inundation. Damages to coastal archeological sites, loss of access to historical sites, and the alteration of cultural landscapes will force changes in the way researchers can study sites, tourists can enjoy places, and descendant communities who have lived in particular areas for time immemorial, and local community members can utilize and relate to landscapes. In the USA, the National Park Service is a primary coastal cultural resource management organization. The National Park Service has been working on climate change adaptation for cultural resources for over a decade; however, there are few examples of parks in which long range climate change adaptation plans for cultural resources have been implemented. Building from 20 semi-structured interviews with cultural resource managers in three parks, we found that institutional structures within the National Park Service, as well as historical conceptual framings specific to the research, recreational, and interpretive values of cultural resources act as barriers to managers’ ability to design and implement climate change adaptation plans. Institutional barriers managers discussed include the dependence of climate change adaptation decisions partnership projects and the leveraging of budgetary and staff resources within NPS that may affect climate change adaptation capacity. We found that park managers often saw impacts in parks that may be associated with climate change, but found it difficult to separate normal maintenance from climate change affected deterioration, which may lead to status quo management actions rather than revised planning for a changing future regime. Conceptual barriers managers discussed revealed a conflict between preservation needs of research versus interpretive uses and while NPS guidance recommends prioritization of cultural resources for preservation at the park level, regional managers were more focused on this topic than park managers. As NPS moves forward with climate change adaptation planning, opportunities to develop and improve cultural resource preservation with new technologies, improved prioritization schemes, and include public input in resource preservation may help coastal managers overcome these barriers.     

Critical Review of Time-Dependent Shortest Path Algorithms: A Multimodal Trip Planner Perspective

Abstract

A multimodal trip planner that produces optimal journeys involving both public transport and private vehicle legs has to solve a number of shortest path problems, both on the road network and the public transport network. The algorithms that are used to solve these shortest path problems have been researched since the late 1950s. However, in order to provide accurate journey plans that can be trusted by the user, the variability of travel times caused by traffic congestion must be taken into consideration. This requires the use of more sophisticated time-dependent shortest path algorithms, which have only been researched in depth over the last two decades, from the mid-1990s. This paper will review and compare nine algorithms that have been proposed in the literature, discussing the advantages and disadvantages of each algorithm on the basis of five important criteria that must be considered when choosing one or more of them to implement in a multimodal trip planner.