A methodology to estimate travel time using dynamic traffic assignment (DTA) under incident conditions

This paper presents results from a research case study that examined the distribution of travel time of origin–destination (OD) pairs on a transportation network under incident conditions. Using a transportation simulation dynamic traffic assignment (DTA) model, incident on a transportation network is executed under normal conditions, incident conditions without traveler information availability, and incident conditions assuming that users had perfect knowledge of the incident conditions and could select paths to avoid the incident location. The results suggest that incidents have a different impact on different OD pairs. The results confirm that an effective traveler information system has the potential to ease the impacts of incident conditions network wide. Yet it is also important to note that the use of information may detriment some OD pairs while benefiting other OD pairs. The methodology demonstrated in this paper provides insights into the usefulness of embedding a fully calibrated DTA model into the analysis tools of a traffic management and information center.     

Factors that affect the ability of people with disabilities to walk or wheel to destinations in their community: a scoping review

ABSTRACT

It is essential that the pedestrian environment accommodates all users so they can participate in everything the community has to offer. However, people with disabilities (PWDs) often find it difficult to navigate this environment because of physical and social accessibility factors. While we know a great deal about which factors act as barriers and facilitators to mobility, we do not know enough about how they influence navigation (i.e. planning a route, en route decisions, and route learning) or how they can be improved. A scoping review was conducted to identify these factors, assess their implications, and suggest future directions. In total, 3394 studies were found and screened, 163 full-text articles were reviewed, and 37 articles met the inclusion criteria for the final review. These studies focused on those with visual impairments, navigating crosswalks, and the cognitive elements of navigation. Future research is needed that includes more types of disabilities, considers the navigational process from planning to arrival, and evaluates interventions.     

Bicycle commuting in an automobile-dominated city: how individuals become and remain bike commuters in Charlotte,North Carolina

Transportation - In Charlotte, North Carolina less than one half of 1% of commuters ride a bicycle to work despite several decades of public investment in bicycle infrastructure and planning. Like...     

Factors Affecting Knowledge,Perceptions, and Attitudes Regarding North Carolina Coastal Reserve Management

During the period May 25–October 28, 2007, we collected data in face-to-face interviews on four sites in the North Carolina Research Reserve system. We subsequently conducted analyses on the effects of education, income, length of visitation, and frequency of visitation on visitor knowledge, perceptions, and attitudes regarding management. Visitors to the sites were well-educated, listed incomes above the state median, and were racially homogeneous. At the overall level, the majority (63%) knew who owned the sites, but only 43% correctly identified the managing agency. The majority also believed that overall conditions at the sites were stable, although those that had been visiting longer perceived conditions as deteriorating. Education was positively correlated with knowledge of ownership and management, and with support for additional rules and enforcement. Neither income, nor frequency of visitation showed any correlation with any of the dependent variables at the overall level. Some site-specific findings differed from the overall findings and varied from site to site. These differences were addressed individually.     

Cultural Models and Shoreline Social Conflict

Along the coast we witness property conflicts that would seem strange at inland locations. To understand why property conflicts seem particularly common and intense along shorelines, one must appreciate that property is enacted by real people in specific places. The successful enactment of property requires sufficiently shared expectations for behavior. Expectations are formed by consulting cultural models, which are inter-subjectively shared cognitive tools. This article describes seven cultural models of property that can play a role in the enactment of property along the shoreline. These are the sovereignty, community, landscape, ecology, commodity, moral order, and productivity models. A focus on cultural models shows how property conflicts can occur when models are not adequately grounded in real world circumstances, when a cultural model is not shared, or when multiple cultural models conflict. This article argues that all three of these types of failures are more likely to occur along shorelines than with inland property. Finally, even though cultural models of property are not hierarchical, this article argues that too much emphasis is currently being placed on the sovereignty and commodity models, and it suggests ways to reestablish a better balance between all of the cultural models of property.     

Evaluating transfer velocity-wind speed relationship using a long-term series of direct eddy correlation CO2 flux measurements

Long-term observations of the marine atmospheric boundary layer were performed by an eddy correlation system, which was set-up on a platform in the Baltic Sea. In this experiment the three-dimensional wind vector and the turbulent fluxes of momentum, sensible and latent heat and CO₂ were measured for one and a half years. Simultaneously the CO₂ partial pressure p_CO2 in surface water was measured by a submersible autonomous moored instrument for CO₂ at the platform in 7-m depth. The high-resolution eddy correlation measurements of the atmospheric CO₂ flux F_CO2, together with the measurements of the CO₂ partial pressure differences between air and sea Δp_CO2 led to a long-term data set which provided the possibility to investigate the parameterization of the CO₂ transfer velocity k as a function of 10-m wind speed u in a statistical manner. From half-hour mean CO₂ fluxes and CO₂ partial pressure differences, k was calculated using k = F_CO2 / (K₀Δp_CO2), with K₀ the CO₂ solubility. The half-hour mean data points, used for the determination of the k–u parameterization, show large scatter. However, assuming a linear, quadratic dependency the analysis yields: k₆₆₀ = 0.365u² + 0.46u (k at 20 °C and salinity 35 psu) with a correlation coefficient of r² = 0.81. The large scatter indicates that the kinetics of the air–sea CO₂ transfer velocity is not only a function of the wind speed alone, but might also be controlled by other environmental parameters and mechanisms, such as sea state and surface coverage with surfactants.     

The implications of travel profiles for transportation investment: The Bronx Center Project

Investment in transportation infrastructure is generally regarded as an effective means for inducing economic growth and employment in a region. However, the ability of such investments to achieve these objectives, to a large extent, depends on the degree to which travel results from these investments support or conflict with present travel patterns and needs in this region. Using this view as a basis, this paper analyzes travel conditions and choices in the Bronx New York, where large scale transportation and other development projects (commonly called the Bronx Center Project) are presently taking place. Using a large data base, composed of census tract information on socio-economic and travel behavior, the paper first examines the travel profile of the Bronx population, by estimating travel choice elasticities. On the basis of these elasticities it then assesses the impact of the Bronx Center Project on travel patterns and trends.     

Modeling schedule recovery processes in transit operations for bus arrival time prediction

Many existing algorithms for bus arrival time prediction assume that buses travel at free‐flow speed in the absence of congestion. As a result, delay incurred at one stop would propagate to downstream stops at the same magnitude. In reality, skilled bus operators often constantly adjust their speeds to keep their bus on schedule. This paper formulates a Markov chain model for bus arrival time prediction that explicitly captures the behavior of bus operators in actively pursuing schedule recovery. The model exhibits some desirable properties in capturing the schedule recovery process. It guarantees provision of the schedule information if the probability of recovering from the current schedule deviation is sufficiently high. The proposed model can be embedded into a transit arrival time estimation model for transit information systems that use both real‐time and schedule information. It also has the potential to be used as a decision support tool to determine when dynamic or static information should be used.