Refuge Island Research Articles

Small-scale alpine topography at low latitudes and high altitudes: refuge areas of the genus Chrysanthemum and its allies

Cultivated chrysanthemum (Chrysanthemum morifolium Ramat.) is an economically important ornamental plant species grown worldwide. However, the origin of the genus Chrysanthemum remains unclear. This study was conducted in the Hengduan Mountains, Yunnan Province. We took advantage of a special geographic region where the southernmost species of Ajania and the highest altitude population of Chrysanthemum indicum coexist to investigate their evolutionary origins. Diversity analysis of 9 populations of 5 species that came from 3 genera was carried out based on morphological traits and SRAP markers. Furthermore, topographical and ecological analyses and surveys of the vegetation communities in the plots were carried out for correlation analysis, and past data were used to reconstruct the ancient topography and vegetation to estimate the migration path and divergence time. We found that Chrysanthemum and Ajania were closely related based on the smooth transition states among marginal female florets and their common pollination system. The genetic relationship between Phaeostigma and Chrysanthemum was relatively distant, and Ajania was between them. Low light intensity and relatively humid habitats may be driving the elongation and evolution of marginal female florets. We found that Chrysanthemum and related genera were largely restricted to stony topographies at an altitude of ~3000 m.a.s.l. and in specialized alpine coniferous (Pinus) and broad-leaved (Quercus) mixed forest marginal communities. These stony topographies have become ecological islands of refuge for these species in the current interglacial period. The Hengduan Mountains play a key role in the evolution, divergence, and survival of Chrysanthemum and its allies.

Pedestrian Road Crossing at Uncontrolled Mid-Block Locations: Does the Refuge Island Increase Risk?

The study investigates the behaviour of pedestrians crossing a road with a refuge island in an urban area to assess whether refuge islands deliver their expected benefit. This type of pedestrian crossings aims at providing a half-way shelter and protection while pedestrians are crossing a road with two-traffic streams. Data has been collected using two video cameras from an urban location in Edinburgh on gaps in traffic flow, rejected and accepted gaps, and critical gaps of pedestrians while crossing from the curb or the median. Data have also been examined to estimate and assess vehicle and pedestrians’ speeds, vehicle type, waiting time, group size and other demographic characteristics of pedestrians. The statistical modelling techniques used include Multiple Linear Regression and Generalised Estimating Equations (GEE). The results show that the critical gap for crossing from the median to the curb is much shorter than that from the curb to the median. Pedestrians appear to be less cautious when crossing from the median to the curb as they are more likely to accept a shorter gap in traffic. This could indicate a shortfall in the design and/or operation of this type of crossing. Further considerations and investigation of what measures could be implemented to enhance safety and reduce risky behaviour at this type of crossing are recommended and certainly encouraged.

Understanding the Safety Impact of Protected Intersection Design Elements: A Driving Simulation Approach

Protected intersections are used to facilitate safe crossings for non-motorized users. As a relatively new treatment in North America, it is essential to understand how their design elements, such as bicycle intersection-crossing pavement markings and corner refuge island size, enhance bicyclist safety. A driving simulation experiment was developed to test the effectiveness of different design elements of protected intersections on driver speeds. Participants were exposed to different protected intersection designs that varied with respect to the corner refuge island width and bicycle intersection-crossing pavement marking levels. Their speed at two parts of the right turn, that is, approach and curve speed, was analyzed. A combination of design elements, participant demographics, or bicyclist presence at the intersection affects driver behavior at a protected intersection. The results indicate that the presence of a bicyclist crossing a protected intersection significantly reduces speeds for drivers performing a right turn. Corner refuge islands with larger width were found to reduce speed at the curve as they were accompanied by larger curb extensions which essentially reduce the space for the automobiles. Bicycle intersection-crossing pavement markings influenced only approach speeds prior to the actual turn since that is the location where they were the most visible. Age, gender, and bicycling frequency were observed to affect turning speeds, indicating that design elements alone cannot determine the safety effectiveness of a protected intersection. The findings of this study can guide the implementation of protected intersections.

The safety and conspicuity of pedestrian crossing at roundabouts: The effect of median refuge island and zebra markings

Roundabouts are one of the most used road intersections because, compared to signalized ones, they reduce conflict points between traffic flows and moderate driving speed. Great attention should also be paid to vulnerable road users at roundabouts. According to accident statistics, in fact, accessibility of pedestrians and cyclists is not always ensured.This paper has evaluated the effects on the visibility of pedestrian crossing before and after the displacement of zebra markings, moved before intersections, and the introduction of media refuge islands and “Yield here to pedestrians” vertical signs. The above effects have been assessed by before-after analysis of speed and visual behaviour of drivers approaching the crosswalk.Moreover, the analysis of the drivers’ eye movements has highlighted the most salient elements of the pedestrian crossing. The relation between the drivers’ visual behaviour and the vehicle speed have also been calculated. Results have confirmed that the intervention carried out has increased both visibility and safety of the studied pedestrian crosswalks.Zebra markings and the median refuge island have turned out to be the most glanced elements, respectively seen by 93.75% and 56.25% of the drivers, followed by the “Yield here to pedestrians” vertical sign. The mean distance of first fixation of the crosswalk increased from 21.98 m before the intervention, to 40.69 m after it. The drivers perceived the pedestrian crossings from a longer distance after the intervention, and they continued to glance at the crosswalk while approaching it, enhancing their visual attention.

Effects of median refuge island and flashing vertical sign on conspicuity and safety of unsignalized crosswalks

Pedestrian crossings are critical points in terms of road safety because they tend to be characterized by high accident rates. Pedestrian safety at zebra crossings depends mainly on vehicles speed.In this study the effects of median refuge island and “Yield here to pedestrians” flashing vertical sign on pedestrian crossing conspicuity were assessed with a before–after analysis of both speed and visual behaviour of drivers approaching to crosswalks. The elements of the pedestrian crossing that were more salient and how drivers’ visual behaviour was related to speed were assessed analysing drivers’ eye movements. The intervention significantly increased the fixation time to the zebra markings and the addition of the flashing light increased conspicuity and fixation time to the vertical sign. The median refuge island was glanced by 60.7% of the drivers. Distance of first-fixation of the crosswalk increased by 44.7%. Notwithstanding mean and V85 speed parameters were lower after the intervention, the effects on crosswalk visual attention were higher than on speed.

Identifying street design elements associated with vehicle-to-pedestrian collision reduction at intersections in New York City

ObjectiveWe evaluated associations between the installation of eleven street design elements, between 2007 and 2015, and subsequent changes in vehicle-to-pedestrian collisions in New York City. MethodsCollision data were from Accident Location Information System in the New York State Department of Transportation. Safety improvement projects at 118 intersections were reviewed and their implemented street design elements were identified. First, we assessed potential regression-to-the-mean effects using historic trends of pedestrian collision count at the intersection project locations. Second, we used a two-group pretest-posttest design to assess individual element’s associations with pedestrian collision reduction after installations. Pedestrian collision count and pedestrian- and vehicle-based pedestrian collision rates were examined. Third, regression trees were used to classify the intersections with design elements as independent variables for the target variables of collision outcomes, to identify street design element combinations associated with pedestrian collision reductions. ResultsTreatments with pedestrian refuge island or pedestrian plaza had reductions in pedestrian collision count and pedestrian-based collision rate while their comparisons had no changes. Treatments with pedestrian refuge island had a larger reduction in pedestrian collision when combined with lane removal or narrowing. Treatment with curb extension or pedestrian plaza had reductions in vehicle-based pedestrian collision rate while their comparisons had no changes. Other studied elements showed no, small, or insignificant associations with post-project pedestrian collision reductions.

Red-light crossing, crossing time and attitudes to crossing with intelligent green light for pedestrians

In order to increase mobility and promote modal shift to walking, intersections in the city of Aarhus, Denmark, have been equipped with intelligent management of green light for pedestrians. This allows adjustment of green time based on radar detection of pedestrians in the crossing and prolongation of the green time for the pedestrians if required. The effect is examined in a before/after study of a two-stage pedestrian crossing with a centre refuge island in an intersection of four-lane roads. The data consists of responses from an on-site questionnaire including 72+53 individuals and 266+318 hours of video registration of the pedestrian crossing in the before and after study, respectively. The study includes the pedestrians' experiences, the measured time of crossing and the share of pedestrians crossing at red light. The analyses of video recordings are carried out with the video analysing software RUBA. The share of pedestrians who often or frequently only reached the refuge island before red light decreased from 42% to 13%. Video data show that the pedestrians reduced their crossing at red light from 44% to 16% in the remote lane, while the percentage remained virtually unchanged on the closest lane with 16%. The mean crossing time was also reduced by 5 and 6 seconds in- and outside of the peak hour period, respectively. The reductions in mean crossing time were not statistically significant.

Pedestrian Safety on Crosswalks in India - Need of the Hour

A paradigm shift has been observed from ‘moving of vehicles’ to ‘moving of persons’ while planning for transportation facilities in cities. Provision of integrated and barrier free pedestrian facilities is essential to ensure inclusive mobility. Pedestrian facilities are a critical component in producing a pedestrianfriendly environment. In India, the present facilities provided for the pedestrians are not efficient in general and crosswalks (zebra crossings) in particular. The pedestrian casualties in India have registered an increase of 11.7 percent in the year 2017, of which 31 percent have occurred on crosswalks. Therefore, an attempt has been made to overview the level of safety provided on the crosswalks. It has been found that majority of crosswalks are not fulfilling their intended purposes due to improper signage and markings, inadequate maintenance and bad surface condition. Another significant reason hampering the safety of pedestrians at crosswalks has been found to be inappropriate provision of guardrails and pedestrian refuge islands. Hence, some measures have been suggested to augment the pedestrian safety on the crosswalks.

Introduction: Safe Areas as a Response to Humanitarian Crises?

Internationally proclaimed safe areas do not aim to end ongoing wars. Instead, their more limited goal is to create islands of temporary refuge where threatened civilians can find shelter. As intuitively compelling as the idea of safe areas may seem, however, it raises numerous practical and ethical questions. The articles in this special issue draw on history, moral philosophy and political science in order to assess whether safe areas are indeed an appropriate response to humanitarian crises.

Using a historic drought and high-heat event to validate thermal exposure predictions for ground-dwelling birds.

Deviations from typical environmental conditions can provide insight into how organisms may respond to future weather extremes predicted by climate modeling. During an episodic and multimonth heat wave event (i.e., ambient temperature up to 43.4°C), we studied the thermal ecology of a ground‐dwelling bird species in Western Oklahoma, USA. Specifically, we measured black bulb temperature (T bb) and vegetation parameters at northern bobwhite (Colinus virginianus; hereafter bobwhite) adult and brood locations as well as at stratified random points in the study area. On the hottest days (i.e., ≥39°C), adults and broods obtained thermal refuge using tall woody cover that remained on average up to 16.51°C cooler than random sites on the landscape which reached >57°C. We also found that refuge sites used by bobwhites moderated thermal conditions by more than twofold compared to stratified random sites on the landscape but that T bb commonly exceeded thermal stress thresholds for bobwhites (39°C) for several hours of the day within thermal refuges. The serendipitous high heat conditions captured in our study represent extreme heat for our study region as well as thermal stress for our study species, and subsequently allowed us to assess ground‐dwelling bird responses to temperatures that are predicted to become more common in the future. Our findings confirm the critical importance of tall woody cover for moderating temperatures and functioning as important islands of thermal refuge for ground‐dwelling birds, especially during extreme heat. However, the potential for extreme heat loads within thermal refuges that we observed (albeit much less extreme than the landscape) indicates that the functionality of tall woody cover to mitigate heat extremes may be increasingly limited in the future, thereby reinforcing predictions that climate change represents a clear and present danger for these species.

RETRACTED ARTICLE: Assessment of Pedestrian Refuge Islands on Vehicle Speed Changes and Pedestrian Safety: Case Study in Tehran

RETRACTED ARTICLE: Assessment of Pedestrian Refuge Islands on Vehicle Speed Changes and Pedestrian Safety: Case Study in Tehran

Optimization of vehicle and pedestrian signals at isolated intersections

In most traffic signal optimization problems, pedestrian traffic at an intersection receives minor consideration compared to vehicular traffic, and usually in the form of simplistic and exogenous constraints (e.g., minimum green time). This could render the resulting signal timings sub-optimal especially in dense urban areas with significant pedestrian traffic, or when two-stage pedestrian crosswalks are present. This paper proposes a convex (quadratic) programming approach to optimize traffic signal timings for an isolated intersection with one- and two-stage crosswalks, assuming undersaturated vehicular traffic condition. Both vehicle and pedestrian traffic are integrated into a unified framework, where the total weighted delay of pedestrians and vehicles at different types of crosswalks (i.e. one- or two-stage) is adopted as the objective function, and temporal and spatial constraints (e.g. signal phasing plan and spatial capacity of the refuge island) are explicitly formulated. A case study demonstrates the impacts of incorporating pedestrian delay as well as geometric and spatial constraints (e.g., available space on the refuge island) in the signal optimization. A further analysis shows that a two-stage crosswalk may outperform a one-stage crosswalk in terms of both vehicle and pedestrian delays in some circumstances.

Pedestrians' Safety Perception at Signalized Intersections in Shanghai

Abstract Pedestrians are the most vulnerable users at signalized intersections, and their incorrect behaviors such as signal violation, and not crossing at crosswalks etc., which is greatly determined by their safety perceptions, makes the situation even worse. To understand pedestrians’ perception can help traffic engineers to improve facility planning, design and operation so as to provide better experiences of pedestrians crossing at signalized intersections. The study conducted intercept survey at 32 crosswalks in Shanghai, 1286 pedestrians were asked to rate their safety perception from 1 to 5. Pedestrian behavior types have been categorized into three types according to the signal indications when they enter crosswalk, namely Green walkers (GW) who enters in green, Late walkers (LW) who enters in flashing green, and Red walkers (RW) who enters in red. A random-effects ordered logit model has been developed and estimated, the results showed that the refuge island settings and being involved in conflicts had significantly impacts on pedestrian perceptions. All types of pedestrians are in favour of the presence of refuge island, however, LW feel safer if they can stop at refuge island, while the RW perceive less safe. Some recommendation on crosswalk design and operation are proposed based on the conclusions.

Development of Crash Modification Factors for Uncontrolled Pedestrian Crossing Treatments

The objective of this study was to develop crash modification factors for four treatment types: rectangular rapid-flashing beacon (RRFB), pedestrian hybrid beacon (PHB), pedestrian refuge island (RI), and advance yield or stop markings and signs (AS). From 14 cities throughout the United States, 975 treatment and comparison sites were selected. Most of the treatment sites were selected at intersections on urban, multilane streets, because these locations present a high risk for pedestrian crashes and are where countermeasures typically are needed most. For each treatment site, relevant data were collected on the treatment characteristics, traffic, geometric, and roadway variables, and the pedestrian crashes and other crash types that occurred at each site. Cross-sectional regression models and before–after empirical Bayesian analysis techniques were used to determine the crash effects of each treatment type. All four of the treatment types were found to be associated with reductions in pedestrian crash risk, compared with the reductions at untreated sites. PHBs were associated with the greatest reduction of pedestrian crash risk (55% reduction), followed by RRFBs (47% reduction), RIs (32% reduction), and AS (25% reduction). The results for RRFBs had their basis in a limited sample and must be used with caution.

Evaluation of Human Behaviour at Pedestrian Crossings

Road traffic crashes result from a combination of factors related to the road layout, the vehicles, the road users and the way they interact. First the main causes of pedestrian fatalities and the safety effects of road measures (traffic lights, roundabouts and refuge islands) at pedestrian crossings before and after implementation were investigated. The results indicate that there is a strong evidence for the positive effect of these measures especially on the number of the pedestrian related accidents. In the next phase a site survey was conducted in order to estimate the irregular crossing manoeuvres of car drivers and pedestrians at designated pedestrian crossings. Having analysed the irregular movements according to the type of crossing it was found, that car drivers behave the most irregularly at crossings without a refuge island. Crossings equipped with flashing yellow lights, refuge islands and traffic lights require a much more appropriate behaviour from car drivers. In the next phase of the research the waiting time of pedestrians and the delay of vehicle drivers again at pedestrian crossings were surveyed. Our results suggest that there is a need for a strong contribution of the human and the engineering fields to obtain an even more positive change in the safety of vulnerable road users.

Assessment of Pedestrian Refuge Islands on Vehicle Speed Changes and Pedestrian Safety: Case Study in Tehran

Assessment of Pedestrian Refuge Islands on Vehicle Speed Changes and Pedestrian Safety: Case Study in Tehran

Understanding Platform Overcrowding at Bus Rapid Transit Stations

Platform overcrowding is a very common but relatively poorly understood occurrence at most bus rapid transit (BRT) systems in cities in the developing world. Most literature on BRT capacity focuses on vehicle throughput for different types of lane and station configurations; relatively little is known about how different station layouts handle specific volumes of boarding and alighting passengers. In this paper, this gap in knowledge was addressed by building a microscopic simulation model to test the ability of a typical Latin American BRT station (median, high-platform, one bus bay per direction) to handle various volumes of passengers under different scenarios. With this modeling exercise, areas in a station most likely to experience overcrowding were first identified: the median refuge island at the main entrance and the turnstiles. The station performance at those critical points was then evaluated for different passenger volumes, with mainly pedestrian density (persons/m2) as an indicator. Results indicated a pedestrian capacity range for a typical BRT station and also quantified the effect of friction between pedestrians entering and leaving the station. Finally, a regression based on the simulation results was estimated and used to develop a predictive equation for crowding as a function of passenger volumes and direction. The results can help BRT planners better adapt their station designs to forecast passenger volumes and ensure that they provide an adequate level of service.

Evolutionary history of a vanishing radiation: isolation-dependent persistence and diversification in Pacific Island partulid tree snails.

BackgroundPartulid tree snails are endemic to Pacific high islands and have experienced extraordinary rates of extinction in recent decades. Although they collectively range across a 10,000 km swath of Oceania, half of the family’s total species diversity is endemic to a single Eastern Pacific hot spot archipelago (the Society Islands) and all three partulid genera display highly distinctive distributions. Our goal was to investigate broad scale (range wide) and fine scale (within‐Society Islands) molecular phylogenetic relationships of the two widespread genera, Partula and Samoana. What can such data tell us regarding the genesis of such divergent generic distribution patterns, and nominal species diversity levels across Oceania?ResultsMuseum, captive (zoo) and contemporary field specimens enabled us to genotype 54 of the ~120 recognized species, including many extinct or extirpated taxa, from 14 archipelagoes. The genera Partula and Samoana are products of very distinct diversification processes. Originating at the western edge of the familial range, the derived genus Samoana is a relatively recent arrival in the far eastern archipelagoes (Society, Austral, Marquesas) where it exhibits a stepping‐stone phylogenetic pattern and has proven adept at both intra‐and inter‐ archipelago colonization. The pronounced east–west geographic disjunction exhibited by the genus Partula stems from a much older long-distance dispersal event and its high taxonomic diversity in the Society Islands is a product of a long history of within‐archipelago diversification.ConclusionsThe central importance of isolation for partulid lineage persistence and diversification is evident in time-calibrated phylogenetic trees that show that remote archipelagoes least impacted by continental biotas bear the oldest clades and/or the most speciose radiations. In contemporary Oceania, that isolation is being progressively undermined and these tree snails are now directly exposed to introduced continental predators throughout the family’s range. Persistence of partulids in the wild will require proactive exclusion of alien predators in at least some designated refuge islands.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-014-0202-3) contains supplementary material, which is available to authorized users.

Travel Time Delay at Pedestrian Crossings Based on Microsimulations

Analysis of pedestrians is always a current issue, there are frequent crowded trams, tram platforms and long waiting time at zebra crossings. The unsignalized pedestrian crossing analyses are very important because these crossings have a crucial role in transport planning. The accident data show decreasing tendency in the pedestrian accidents although the decrease is not too significant. The rate of the pedestrian accidents on zebra crossings is significant; from 2009 to 2012 this rate was on zebra crossings between 32-34%. The VISSIM microsimulation analyses on unsignalised zebra crossings with and without refuge island. Based on the simulation results and international studies, these two facility types are compared. The article provides a recommendation for these facilities (zebra crossing with and without refuge island) for different vehicle volumes and for medium and high pedestrian volumes.

Towards sustainable pedestrian safety: the Bangladesh context

BackgroundRoad traffic injuries in Bangladesh have now emerged as a serious development challenge and are inhibiting poverty reduction strategies. A major portion of the people killed or seriously injured in...