Showing papers in "Transportation Research Record in 2015"

Using an Activity-Based Model to Explore the Potential Impacts of Automated Vehicles

Abstract: Automated vehicles (AVs) may enter the consumer market with various stages of automation in 10 years or even sooner. Meanwhile, regional planning agencies are envisioning plans for time horizons out to 2040 and beyond. To help decision makers understand the effect of AV technology on regional plans, modeling tools should anticipate its impact on transportation networks and traveler choices. This research uses the Seattle, Washington, region’s activity-based travel model to test a range of travel behavior impacts from AV technology development. The existing model was not originally designed with AVs in mind, so some modifications to the model assumptions are described in areas of roadway capacity, user values of time, and parking costs. Larger structural model changes were not yet considered. Results of four scenario tests show that improvements in roadway capacity and in the quality of the driving trip may lead to large increases in vehicle miles traveled, while a shift to per mile usage charges may count...

Cooperative Adaptive Cruise Control

Abstract: Cooperative adaptive cruise control (CACC) includes multiple concepts of communication-enabled vehicle following and speed control. Definitions and classifications are presented to help clarify the distinctions between types of automated vehicle-following control that are often conflated with each other. A distinction is made between vehicle-to-vehicle (V2V) CACC, based on vehicle–vehicle cooperation, and infrastructure-to-vehicle CACC, in which the infrastructure provides information or guidance to the CACC system (such as the target set speed value). In V2V CACC, communication provides enhanced information so that vehicles can follow their predecessors with higher accuracy, faster response, and shorter gaps; the result would be enhanced traffic flow stability and possibly improved safety. A further distinction is made between CACC, which uses constant-time-gap vehicle following (forming CACC strings), and automated platooning, which uses tightly coupled, constant-clearance, vehicle-following strategies....

Analyzing Cell Phone Location Data for Urban Travel: Current Methods, Limitations, and Opportunities

Abstract: Travelers today use technology that generates vast amounts of data at low cost. These data could supplement most outputs of regional travel demand models. New analysis tools could change how data and modeling are used in the assessment of travel demand. Recent work has shown how processed origin–destination trips, as developed by trip data providers, support travel analysis. Much less has been reported on how raw data from telecommunication providers can be processed to support such an analysis or to what extent the raw data can be treated to extract travel behavior. This paper discusses how cell phone data can be processed to inform a four-step transportation model, with a focus on the limitations and opportunities of such data. The illustrated data treatment approach uses only phone data and population density to generate trip matrices in two metropolitan areas: Boston, Massachusetts, and Rio de Janeiro, Brazil. How to label zones as home- and work-based according to frequency and time of day is detaile...

Effects of Autonomous Vehicle Ownership on Trip, Mode, and Route Choice

Abstract: Autonomous vehicles (AVs) may significantly change traveler behavior and network congestion. Empty repositioning trips allow travelers to avoid parking fees or share the vehicle with other household members. Computer precision and reaction times may also increase road and intersection capacities. AVs are currently being test driven on public roads and may be publicly available within the next two decades; they therefore may be within the span of 20- to 30-year planning analyses. Despite this time scale, AV behavior has yet to be incorporated into planning models. This paper presents a multiclass, four-step model that includes AV repositioning to avoid parking fees (although incurring additional fuel costs) and increases in link capacity as a function of the proportion of AVs on the link. Demand is divided into classes by value of time and AV ownership. Mode choice—parking, repositioning, or transit—is determined through a nested logit model. Traffic assignment is based on a generalized cost function of ti...

Implementing Mobility as a Service: Challenges in Integrating User, Commercial, and Societal Perspectives

Abstract: This paper presents insights from a six-month field operational test (FOT) in Gothenburg, Sweden, during which 195 participants tested the UbiGo mobility service for everyday travel. The service integrates both public and private solutions into a new type of “collective transport”, thereby contributing to Swedish societal goals of a reduction of private car use and ownership. A triangulation approach to data sources and collection methods has been adopted in order to identify matches and mismatches between the expectations and experiences of three stakeholder groups: users (FOT participants/customers), commercial actors (the mobility broker and service providers), and society. Identified matches include the “transportation smorgasbord” concept, reducing private car ownership, and increased pre-trip planning. Identified mismatches relate to the greater than expected reduction in car use; the respective business models of the mobility broker and service providers; back office administration; and the smartphone platform. Gaps include the infeasibility of some trips and the need for more carsharing sites. All in all, the FOT was successful with 93% of participants satisfied with their travel and 97% wanting to continue using UbiGo. However, the mismatches and gaps need to be resolved or at least deliberated upon in order to create a commercially viable mobility service. Based on the experience gained, the authors conclude that truly “collective transport” must involve close cooperation between public and private actors, and the consideration of at least these three, sometimes conflicting, stakeholders’ perspectives in order to create integrated solutions. Furthermore, new business models are needed to address the challenges associated with future, integrated, urban mobility solutions.

Bicycle sharing and public transit: does Capital Bikeshare affect Metrorail ridership in Washington, D.C.?

Abstract: Bicycle-sharing programs have emerged around the world. Theoretically, the effect of bicycle sharing on more conventional transit modes can take a substitute or complementary form. On one hand, bicycle sharing could substitute for conventional transit as a convenient and sustainable travel option. On the other hand, bicycle sharing may complement such transit by seamlessly connecting transit stations with origins and destinations and thus increase accessibility. However, the questions of how and to what extent bicycle-sharing programs affect public transit ridership remain to be answered, despite the attempts of a few empirical and quantitative studies. This study examined the impact of the Capital Bikeshare (CaBi) program on Metrorail’s ridership in Washington, D.C. When CaBi trips were mapped, it was observed that Metrorail stations had been important origins and destinations for CaBi trips. Six of seven CaBi stations producing more than 500 trips were located close to Metrorail stations. This study con...

Trajectory Data and Flow Characteristics of Mixed Traffic

Abstract: Models of driving behavior (e.g., car following and lane changing) describe the longitudinal and lateral movements of vehicles in the traffic stream. Calibration and validation of these models require detailed vehicle trajectory data. Trajectory data about traffic in cities in the developing world are not publicly available. These cities are characterized by a heterogeneous mix of vehicle types and by a lack of lane discipline. This paper reports on an effort to create a data set of vehicle trajectory data in mixed traffic and on the first results of analysis of these data. The data were collected through video photography in an urban midblock road section in Chennai, India. The trajectory data were extracted from the video sequences with specialized software, and the locally weighted regression method was used to process the data to reduce measurement errors and obtain continuous position, speed, and acceleration functions. The collected data were freely available at http://toledo.net.technion.ac.il/down...

Use of Smart Card Fare Data to Estimate Public Transport Origin–Destination Matrix

Abstract: Over the past few years, several techniques have been developed for using smart card fare data to estimate origin–destination (O-D) matrices for public transport. In the past, different walking distance and allowable transfer time assumptions had been applied because of a lack of information about the alighting stop for a trip. Such assumptions can significantly affect the accuracy of the estimated O-D matrices. Little evidence demonstrates the accuracy of O-D pairs estimated with smart card fare data. Unique smart card fare data from Brisbane, Queensland, Australia, offered an opportunity to assess previous methods and their assumptions. South East Queensland data were used to study the effects of different assumptions on estimated O-D matrices and to conduct a sensitivity analysis for different parameters. In addition, an algorithm was proposed for generating an O-D matrix from individual user transactions (trip legs). About 85% of the transfer time was nonwalking time (wait and short activity time). More than 90% of passengers walked less than 10 min to transfer between alighting and the next boarding stop; this time represented about 10% of the allowable transfer time. A change in the assumed allowable transfer time from 15 to 90 min had a minor effect on the estimated O-D matrices. Most passengers returned to within 800 m of their first origin on the same day.

Intersection Auctions and Reservation-Based Control in Dynamic Traffic Assignment

Abstract: Autonomous vehicle (AV) technology is maturing, and AVs are being test-driven on public roads. A promising intersection control policy, tile-based reservation (TBR), proposed by Dresner and Stone in 2004, could improve intersection capacity beyond the capabilities of optimized traffic signals. Although TBR has been studied in several microsimulation models, it has yet to be analyzed under user equilibrium behavior. In this study, TBR was modeled in the dynamic traffic assignment to draw on the extensive literature on vehicle routing behaviors. With the proposed model, TBR can be computationally simulated on large city networks, with the goal of solving the traffic assignment problem. TBR also arbitrarily prioritizes vehicle movement, and high-value-of-time travelers may be able to gain priority through intersection auctions, as suggested by the literature. An in-depth study of simple intersection auctions found that much of the benefit (over first-come, first-served prioritization) resulted from the rando...

Effect of Aging on Adhesion Properties of Asphalt Mixtures with the Use of Bitumen Bond Strength and Surface Energy Measurement Tests

Abstract: The interaction between asphalt binder and aggregate is fundamental to ensure adequate performance of asphalt mixtures, mainly in the presence of water. The work of adhesion generated between both materials directly affects the resistance of asphalt mixture to moisture damage, because it measures the ease with which water can displace asphalt binder from the aggregate surface. The objective of this study was to characterize the bond strength between asphalt and several aggregate sources. A PG 64-22 neat binder was modified with several additives to determine the effect on adhesion: polymers, nanomaterials, and adhesion promoters. To measure the strength of adhesion, the bitumen bond strength (BBS) test and contact angle measurements between asphalt binder and the aggregate surface by means of goniometry were used. The surface energy of the asphalt and the aggregate, with and without the presence of water, was estimated also. Testing was performed on all binders and on each binder–aggregate combination aft...

Perceived Service Quality, Customer Satisfaction, and Behavioral Intentions: Structural Equation Model for the Metro of Seville, Spain

Abstract: This paper investigates the relationship between perceived service quality, customer satisfaction, and behavioral intentions for Metro of Seville, Spain, a metropolitan, partially underground light rail transit (LRT) service. A total of 3,211 users participated in the case study by completing a questionnaire with four parts: users’ attitudes about the public transit service, users’ perceptions of service quality, travel habits, and socioeconomic characteristics of the participants. A seven-step analytic process was applied to the questionnaire instrument to adapt it to the specific characteristics of the service, to purify the scale, and to reduce the number of items describing the service into fewer underlying dimensions. Then, the above-mentioned relationships between perceptions, satisfaction, and intentions of users concerning the LRT service were estimated with the use of a structural equation model (SEM) approach. Three SEMs were calibrated: one for all the users, one for captive users, and one for ...

Logistics Spatial Patterns in Paris: Rise of Paris Basin as Logistics Megaregion

Abstract: The purpose of this study is to consider the spatial distribution of freight and logistics facilities in both the Paris region and the Paris megaregion (the Paris basin) between 2000 and 2012 A major rise in the number of warehousing and logistics facilities has been documented since the beginning of the 2000s in both areas In terms of spatial characteristics, this growth illustrates both centrifugal processes, from the urban core to the suburban and exurban areas of the region, and centripetal processes, from the margins of the Paris basin to the edges of the Paris region The logistics system is a global distribution process from international supply chains to urban supply chains In this process, freight hubs serve as switches connecting these two scales of the logistics system This role explains part of the locational patterns of logistics and warehousing facilities in Paris, both at the metropolitan scale of the Ile-de-France region and at the megaregional scale of the Paris basin Areas of furthe

Parking Reservation for Managing Downtown Curbside Parking

Abstract: This paper discusses a smartphone-based parking reservation system that manages a finite number of curbside parking spaces located at various places in a downtown area. Parking reservation schemes are designed to minimize the total social cost of parking, which is assumed to be a weighted sum of the cruising times for drivers to travel from their current locations to allocated parking spaces and the walking times from parking places to final destinations. With the assumption of perfect information on cruising and walking times, a simple reservation scheme to achieve an optimum allocation of parking spaces is presented. However, although the locations of drivers can be retrieved from their smartphones, it is shown that drivers have an incentive to misreport their final destinations for their own benefit, which compromises the system benefit. Thus, the Vickrey–Clark–Groves mechanism is applied to determine the allocation of parking spaces and parking fees to minimize the total social cost while ensuring tha...

Simulated traffic conflicts: do they accurately represent field-measured conflicts?

Abstract: Recently, there has been growing interest in using microsimulation models to assess the safety of road facilities by analyzing vehicle trajectories and estimating conflict indicators. Using microsimulation models in safety studies can have several advantages, although concerns have been raised about the ability of these models to represent unsafe vehicle interactions and near misses realistically as well as their need for rigorous calibration. The main objective of this study was to investigate the relationship between field-measured and simulated conflicts at an urban signalized intersection in Surrey, British Columbia, Canada. Sixty hours of recorded traffic data were collected in 2 days and used in the conflict analysis. Automated video-based computer vision techniques were used to extract vehicle trajectories and identify conflicts on all four approaches to the intersection. Conflict measures (e.g., time to collision) and location were determined and compared with simulated conflicts from a microscopic simulation model (VISSIM) using the Surrogate Safety Assessment Model (SSAM). A two-step calibration procedure was proposed to enhance correlation between simulated and field-measured conflicts. The first calibration step was matching actual field conditions (desired speed and arrival type) to ensure that VISSIM gives real average delay values. The second step was the use of sensitivity analysis followed by a genetic algorithm procedure to calibrate the VISSIM parameters that had the biggest effect on the simulated conflicts. Finally, conflict heat maps were provided to compare field-measured with simulated conflict locations. The results highlighted the importance of model calibration and identified several limitations of the SSAM.

Quantitative Characterization of Binder Blending: How Much Recycled Binder Is Mobilized During Mixing?

Abstract: The current tendency in the asphalt paving industry is to increase the use of recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS). However, a major concern that limits the use of RAP or RAS is the uncertainty about how much of the aged binder in RAP or RAS can be blended into virgin binder. Studies have focused on the diffusion between old and new binders. However, little research has been conducted to determine how much recycled binder could be mobilized and made available to coat aggregates. This study developed a laboratory procedure to quantify the rate at which aged binder was mobilized for recycled mixtures containing up to 80% RAP and 10% RAS. A new term, “large molecular size percentage (LMSP),” was derived from gel permeation chromatography testing and used to characterize recycled and virgin binders as well as their blends. Blending charts were generated for virgin–aged binder blends containing 0% to 100% RAP or RAS binder in LMSP. The relationship was found to be linear between ...

Alternative Approach toward the Aging of Asphalt Binder

Abstract: Awareness that natural, financial, and energy resources are scarce goods has increased. Thus demand is growing for infrastructure that is not only of high quality but also efficient. Efficiency, in this case, aims to optimize cost and energy consumption over the complete life cycle of a structure. The objective is to build long-lasting infrastructure with low maintenance demands and with high recycling potential after it has reached the end of its service life. For bituminous bound materials, the aging of asphalt binder has a crucial impact on durability and recyclability. Because asphalt binder is organic by nature, the thermal and oxidative aging processes affected by chemical and structural changes occur when asphalt mixes first are produced and applied and continue over the course of their service life. Increasing stiffness and brittleness of the binder make pavement more prone to thermal and fatigue cracking. The interdisciplinary research project reported here worked toward a better understanding of...

Resilience of Coastal Transportation Networks Faced with Extreme Climatic Events

Abstract: Infrastructure systems, especially those including civil infrastructure (e.g., transportation networks, water distribution systems, and power transmission lines) are inarguably critical to the everyday functions of society. The ability of an infrastructure system to withstand, to adapt to, and to recover rapidly from extreme events is paramount in the ability to serve users. The effects of historical climatic events have resulted in a growing concern for preparedness against such hazards, specifically in coastal communities. The continuing function of society and its economy relies heavily on an accessible transportation network. Roads, highways, railroads, ports, and airports make up a complex infrastructure vital for the travel of goods and people. Extreme events of climatic source that disturb the transportation network affect all aspects of daily life, both directly and indirectly. To estimate the resilience of coastal transportation networks to extreme events, topological graph properties are measure...

Factor Association with Multiple Correspondence Analysis in Vehicle–Pedestrian Crashes:

Abstract: In the United States, about 14% of total crash fatalities are pedestrian related. In 2012, 4,743 pedestrians were killed, and 76,000 pedestrians were injured in vehicle–pedestrian crashes in the United States. Vehicle–pedestrian crashes have become a key concern in Louisiana as a result of the high percentage of fatalities there in recent years. In 2012, pedestrians accounted for 17% of total crash fatalities in the state. This study used multiple correspondence analysis (MCA), an exploratory data analysis method used to detect and represent underlying structures in a categorical data set, to analyze 8 years (2004 to 2011) of vehicle–pedestrian crashes in Louisiana. Pedestrian crash data are best represented as transactions of multiple categorical variables, so the use of MCA was a unique choice to determine the relationship of the variables and their significance. The findings indicated several nontrivial focus groups (e.g., drivers with high-occupancy vehicles, female drivers in bad weather conditions, ...

Short-Term Prediction of Ridership on Public Transport with Smart Card Data

Abstract: Public transport operators are collecting massive amounts of data from smart card systems In the Netherlands, every passenger checks in and checks out; this system creates detailed records of demand patterns In buses and trams, users check in and check out in the vehicle; this factor provides good information on route choice Options for analyzing smart card data and performing what-if analyses with transport planning software were explored On the basis of big data, this new generation of transport demand models added to the existing range of transport demand models and approaches The goal was to provide public transport operators with a simple (easy-to-build) model to perform what-if analyses The data were converted to passengers per line and an origin–destination matrix between stops This matrix was assigned to the network to reproduce the measured passenger flows, and then what-if analysis became possible With fixed demand, line changes could be investigated With the introduction of an elastic demand model, changes in the level of service realistically affected passenger numbers This method was applied to a case study in The Hague, Netherlands Smart card data were imported into a transport model and connected with the network The tool proved to be valuable to operators, who gained insights into the effects of small changes

Predicting Crashes on Expressway Ramps with Real-Time Traffic and Weather Data:

Abstract: Limited research has been conducted on real-time crash analysis of expressway ramps, although there have been many studies in recent years on estimating real-time crash prediction models for main lines. This study presents Bayesian logistic regression models for single-vehicle (SV) and multivehicle (MV) crashes on expressway ramps by using real-time microwave vehicle detection system data, real-time weather data, and ramp geometric information. The results find that the logarithm of the vehicle count, average speed in a 5-min interval, and visibility are significant factors for the occurrence of SV and MV crashes. The Bayesian logistic regression models show that curved ramps and wet road surfaces would increase the possibility of an SV crash, and off-ramps would result in high risk of MV crashes. The high standard deviation of speed in a 5-min interval would significantly increase MV crash likelihood. Random Forests software was applied in variable importance analysis, and the results revealed that the most important factors influencing crashes on ramps were traffic variables, the second most important factors are weather variables, and the least important but still significant factor was the ramp geometry.

Can Time Proximity Measures be Used as Safety Indicators in All Driving Cultures?: Case Study of Motorcycle Safety in China

Abstract: Limitations associated with traditional collision-based safety analysis techniques led to a growing interest in the use of surrogate safety measures such as the traffic conflict technique. This interest was facilitated by advances in automated video-based data collection methods that helped to overcome the reliability issues associated with manual collection of data on traffic conflicts. Various objective conflict indicators that measure various spatial and temporal aspects of user proximity are available to measure the severity of traffic events. These time-proximity conflict measures assume that proximity is a surrogate for conflict severity. However, this assumption may not be valid in many driving environments. The objective of this paper is to investigate whether time-proximity conflict measures can be a good indicator of safety in less-organized traffic environments with highly mixed road users. A case study of motorcycle conflicts in a highly congested shared intersection in Shanghai, China, was us...

Comparison of Permeability and Clogging Characteristics of Porous Asphalt and Pervious Concrete Pavement Materials

Abstract: Porous pavements have been used for many years worldwide because of their unique functional benefits, including improved wet-weather driving safety, reduced tire–pavement noise, lower peak flow load of road drainage systems, and replenishment of groundwater supplies. These benefits are derived from the relatively high porosity and permeability of the porous pavement layers. In the design of a porous pavement, two key considerations are its drainage capacity and its ability to retain the drainage capacity during its service life. In this research, which used a permeability coefficient as the drainage capacity parameter, a laboratory study was performed to examine the drainage and clogging characteristics of two common forms of porous materials used in porous pavement construction, namely porous asphalt and pervious concrete. The experimental program considered four target porosity levels for each of the two pavement materials: 10%, 15%, 20%, and 25%. Clogging was created by introducing clogging materials p...

Sustainable Pavement Management: Integrating Economic, Technical, and Environmental Aspects in Decision Making

Abstract: Sustainability, which is founded on the reconciliation of economic, environmental, and social aspects, has become a major issue for infrastructure managers. The economic and environmental impacts of pavement maintenance are not negligible. More than $400 billion are invested globally each year in pavement construction and maintenance. These projects increase the environmental impacts of vehicle operation by 10%. Because maintenance should be technically appropriate, infrastructure managers must integrate technical, economic, and environmental aspects in the evaluation of maintenance alternatives over the life cycle of a pavement. However, these aspects are normally assessed in measurement units that are difficult to combine in the decision-making process. This research examined and compared methods for the integrated consideration of technical, economic, and environmental aspects, and this study aimed to assist highway agencies, researchers, and practitioners with the integration of these aspects for the ...

Prediction of Field Aging Gradient in Asphalt Pavements

Abstract: The aging of asphalt pavements is a key factor that influences pavement performance. Aging can be characterized by laboratory tests and prediction models. Common aging prediction models use the change of physical or chemical properties of asphalt binders based on regression techniques or aging reaction kinetics. The objective of this study was to develop a kinetics-based aging prediction model for the mixture modulus gradient in asphalt pavements to study long-term in-service aging. The proposed model was composed of three submodels for baseline modulus, surface modulus, and aging exponent to define the change of the mixture modulus with pavement depth. The model used kinetic parameters (aging activation energy and preexponential factor) of asphalt mixtures and combined the two reaction rate periods (fast-rate and constant-rate). Laboratory-measured modulus gradients of 29 field cores at different ages were used to determine the model parameters. The laboratory testing condition was converted to the field condition at a given age and corresponding temperature by introducing the rheological activation energy to quantify the temperature dependence of field cores at each age. The end of the fast-rate period or the beginning of the constant-rate period was accurately identified to model these two periods and to determine the associated parameters separately. The results showed that the predictions matched well with the measurements and the calculated model parameters were verified. The proposed aging prediction model took into account the major factors that affect field aging speed of an asphalt pavement, such as the binder type, aggregate type, air void content, pavement depth, aging temperature, and aging time.

Capacity Drop: Relationship Between Speed in Congestion and the Queue Discharge Rate

Abstract: It has been empirically observed for years that the queue discharge rate is lower than the prequeue capacity. This difference is called the capacity drop. The magnitude of capacity drop varies over a wide range, depending on the local traffic conditions. However, it is unknown what determines the capacity drop value. No thorough empirical analysis has yet revealed a reliable relationship between the capacity drop and the congestion level. This paper fills the gap by revealing, through empirical analysis, the relationship between vehicle speed in congestion and the queue discharge rate. The research studies congested states in which speed ranges from 6 to 60 km/h. The queue discharge rate is shown to increase considerably with increasing speed in the congestion. In contrast to previous research, this study bases the relationship on empirical data collected on freeways, and the data present a sufficiently large observation sample. A discussion about the influence of weather and study site characteristics on the discharge rate indicates that the relationship needs site-specific calibrations. This study provides a better prediction of capacity drop and a better theoretical understanding of the fluctuations in capacity drop.

Integrating CEMDAP and MATSIM to Increase the Transferability of Transport Demand Models

Abstract: An activity-based approach to transport demand modeling is considered the most behaviorally sound procedure to assess the effects of transport policies. This paper investigates whether it is possible to transfer an estimated model for activity generation from elsewhere (the estimation context) and use local area (application context) traffic counts to develop a local area activity-based transport demand representation. Here, the estimation context is the Los Angeles, California, area, and the application context is Berlin. Results in this paper suggest that such a transfer approach is feasible, according to a comparison with a Berlin travel survey. Additional studies need to be undertaken to examine the stability of the results obtained in this paper.

Networkwide Impacts of Vehicle Ecospeed Control in the Vicinity of Traffic Signalized Intersections

Abstract: Ecospeed control is an advanced ecodriving or ecovehicle control algorithm that uses signal phasing and timing information from signalized intersections to generate fuel-optimum vehicle trajectories. The proposed algorithm uses connected vehicles technology to communicate between vehicles and the infrastructure. The research presented in this paper integrates the algorithm with state-of-the-art traffic simulation software, in this case the INTEGRATION software, to develop a tool capable of analyzing and evaluating systemwide impacts. The algorithm uses dynamic programming to generate fuel-efficient vehicle trajectories in the vicinity of traffic signalized intersections by controlling the vehicle variable limiting speed (VLS) to minimize fuel consumption while maintaining safe car-following behavior. Ecospeed control uses constraints upstream and downstream of the intersection to generate a longitudinal VLS function. Multiple simulations for levels of congestion (volume-to-capacity ratios) and levels of m...

Influence of Bike Lane Buffer Types on Perceived Comfort and Safety of Bicyclists and Potential Bicyclists

Abstract: Buffered and protected bike lanes are increasingly recognized as a valuable tool in enticing potential or wary cyclists to use a bicycle for transportation. These facilities—which provide extra space and (in the case of protected bike lanes) physical separation from motor vehicles—have been studied and are preferred by many bicyclists over traditional bike lanes. There has been little research, however, on the difference between buffer types and how they affect people’s sense of the safety and comfort of bicycling. This paper uses data from surveys collected for a multicity study of newly constructed protected bike lanes to examine the influence of various hypothetical and actual buffered bike lane designs (both with and without physical protection) from the perspective of current bicyclists (n = 1,111) and of residents living near the new facilities (n = 2,283) who could be potential bicyclists. Findings suggest that striped or painted buffers offer some level of increased comfort, whereas buffers with s...

Flexible and Robust Method for Missing Loop Detector Data Imputation

Abstract: This study is primarily focused on missing traffic sensor data imputation for the purpose of improving the coverage and accuracy of traffic analysis and performance estimation. Missing data, whether attributable to hardware failure or error detection and removal, are a constant problem in loop and other traffic detector data sets. As the rate of missingness increases, the treatment of missing values quickly becomes the controlling factor in overall data quality. Previously, several imputation approaches have been developed for traffic data. However, few studies aim at handling the traffic data with large blocks of missing values for networkwide implementation. A proven predictive mean matching multiple imputation method is introduced; it was applied to loop detector volume data collected on Interstate 5 in Washington State. With the use of the iterative multiple imputation by chained equations approach, the spatial correlation between nearby detectors was considered for prediction, and the presence of mis...

Hurricane evacuation route choice of major bridges in Miami Beach, Florida

Abstract: Evacuation is a typical recourse to prevent loss of life if a high storm surge occurs, especially in hurricane-prone regions. Bridges are the key locations of bottlenecks. Because of the specific geographic shape and roadway network of Miami Beach, Florida, residents need to evacuate over one of the six major bridges or causeways: MacArthur Causeway, Venetian Causeway, Julia Tuttle Causeway, John F. Kennedy Causeway, Broad Causeway, and Haulover Bridge. A mixed logit model is presented to identify the determining factors for evacuees from Miami Beach in selecting one of these bridges during a major hurricane. The model was developed by using data obtained from a survey that included a hypothetical Category 4 (major) hurricane scenario to reveal the most likely plans for evacuees from this area. The estimation findings suggest that the preference over a given bridge involves a complex interaction of variables, such as distance to reach the evacuation destination, evacuation-specific characteristics (evacuation day, time, mode, and destination), and evacuee-specific characteristics (gender, race, evacuation experience, and living experience). The normally distributed random parameters in the model account for the existence of unobserved heterogeneity across different observations. The findings of this study will help emergency officials and policy makers to develop efficient operational measures and better evacuation plans for a major hurricane by determining different fractions of people taking each of the six bridges.