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47
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August 2015 - present
August 2010 - August 2015
Publications
Publications (47)
The National Highway Traffic Safety Administration reported that the number of bicyclist fatalities has increased by more than 35% since 2010. One of the main reasons associated with cyclists’ crashes is the adverse effect of drivers’ cognitive distractions. However, very limited studies have evaluated the impact of cyclists’ cognitive distraction...
Virtual reality (VR) simulation offers a proactive, cost effective, immersive, and low risk platform for studying pedestrian safety. Within immersive virtual environments (IVEs), existing and alternative design conditions and intelligent transportation systems (ITS) technologies can be directly compared, prior to real-world implementation, to asses...
Researchers and planners require ridership data to study factors that influence people’s choice to use transit. However, the data can be challenging to obtain directly from transit agencies. Crowdsourced big data platforms such as StreetLight promise easily accessible ridership-related data in standard formats. It is important to assess the reliabi...
The National Highway Traffic Safety Administration reported that the number of bicyclist fatalities has increased by more than 35% since 2010. One of the main reasons associated with cyclists' crashes is the adverse effect of high cognitive load due to distractions. However, very limited studies have evaluated the impact of secondary tasks on cogni...
Recent advancements of virtual reality (VR) technology (such as the HTC Vive or Oculus Quest) have opened the door for lower cost and lower risk methods to study pedestrians' behavior and perception of safety, offering a higher degree of data resolution and level of realism compared to previous pedestrian simulators. This research aims to address t...
Understanding cyclist behaviors and preferences is critical to improve safety and increase mode share. However, real-world cycling data is scarce and on-road testing presents safety concerns. This study presents a novel way of studying cyclists’ perceptions of bicycle infrastructure design alternatives using immersive virtual environments modeled a...
The integration of human-centric approaches has gained more attention recently due to more automated systems being introduced into our built environments (buildings, roads, vehicles, etc.), which requires a correct understanding of how humans perceive such systems and respond to them. This paper introduces an Immersive Virtual Environment-based met...
The integration of human-centric approaches has gained more attention recently due to more automated systems being introduced into our built environments (buildings, roads, vehicles, etc.), which requires a correct understanding of how humans perceive such systems and respond to them. This paper introduces an Immersive Virtual Environment-based met...
Injuries and fatalities for vulnerable road users, especially bicyclists and pedestrians, are on the rise. To better inform design for vulnerable road users, we need to evaluate how bicyclist and pedestrian behavior and physiological states change in different roadway design and contextual settings. Previous research highlights the advantages of us...
Privately-owned automated vehicles (PAVs) can relocate themselves elsewhere after arriving at destinations, thereby inducing empty vehicle mile traveled (VMT) and more greenhouse gas emissions. This paper examines travelers’ preferences for PAV relocation, using stated preference surveys distributed in the Seattle and Kansas City regions in the U.S...
Low-lying coastal cities across the world are vulnerable to the combined impact of rainfall and storm tide. However, existing approaches lack the ability to model the combined effect of these flood mechanisms, especially under climate change and sea level rise (SLR). Thus, to increase flood resilience of coastal cities, modeling techniques to impro...
Recent reports indicate that cyclist fatalities are rising. Unlike automobile driver crash and safety studies, there is very limited information and data on how different environmental or design features impact cyclists’ behaviors, attention, and awareness. Real world studies evaluating cyclist behavior are limited due to their inherent safety risk...
The environmental benefits of zero-emission vehicles (ZEVs) are affected by both consumer adoption and usage patterns. While numerous studies examine consumers’ stated or revealed preferences for ZEV adoption, ZEV usage patterns have received less attention. Based on the 2019 California vehicle survey data, this paper analyzes the annual mileage of...
Crowdsourced Personal Weather Stations (PWSs) adoption has been growing rapidly and provides the potential to fill in hyper-local rainfall observation gaps. However, current adoption patterns exhibit spatial biases that must be understood when using the data for modeling and decision-making. Here, we first examine the PWS rainfall spatial represent...
As a healthier and more sustainable way of mobility, cycling has been advocated by literature and policy. However, current trends in bicyclist crash fatalities suggest deficiencies in current roadway design in protecting these vulnerable road users. The lack of cycling data is a common challenge for studying bicyclists' safety, behavior, and comfor...
Injuries and fatalities for vulnerable road users, especially bicyclists and pedestrians, are on the rise. To better inform design for vulnerable road users, we need to conduct more studies to evaluate how bicyclist and pedestrian behavior and physiological states change in different roadway designs and contextual settings. Previous research highli...
Low-lying coastal cities across the world are vulnerable to the combined impact of rainfall and storm tide. However, existing approaches lack the ability to model the combined effect of these flood mechanisms. Thus, to increase flood resilience, modeling techniques to improve understanding and prediction of the combined effect of these flood hazard...
Climate change and sea-level rise are increasingly leading to higher and prolonged high tides, which, in combination with the growing intensity of rainfall and storm surges, and insufficient drainage infrastructure, result in frequent recurrent flooding in coastal cities. There is a pressing need to understand the occurrence of roadway flooding inc...
Recent reports indicate that cyclist fatalities are rising. Unlike automobile driver crash and safety studies, there is very limited information and data on how different environmental or design features impact cyclists’ behaviors, attention, and awareness. Real world studies evaluating cyclist behavior are limited due to their inherent safety risk...
Climate change and sea level rise have increased the frequency and severity of flooding events in coastal communities. This study quantifies transportation impacts of recurring flooding using crowdsourced traffic and flood incident data. Agency-provided continuous count station traffic volume data at 12 locations is supplemented by crowd-sourced tr...
Previous studies on factors affecting electric vehicle (EV) adoption mainly rely on individual stated preference surveys or aggregate market share analyses. This paper applies both approaches to study EV adoption patterns in the state of Virginia to compare and contrast findings from the two methods. An individual-level vehicle fuel type choice mod...
Bicycle infrastructure can increase the comfort of bicyclists, grow bicycle mode share, and reduce bicycle-vehicle crashes. With worldwide goals to increase non-motorized vehicle travel and decrease traffic fatalities, successful bicycle infrastructure implementation is a key component to safer and more comfortable bicycling environments. Yet, tran...
Injuries and fatalities for vulnerable road users, especially bicyclists and pedestrians, are on the rise. To better inform design for vulnerable road users, we need to conduct more studies to evaluate how bicyclist and pedestrian behavior and physiological states change in different roadway designs and contextual settings. Previous research highli...
Increasingly, experts are forecasting the future of transportation to be shared, autonomous and electric. As shared autonomous electric vehicle (SAEV) fleets roll out to the market, the electricity consumed by the fleet will have significant impacts on energy demand and, in turn, drive variation in energy cost and reliability, especially if the cha...
Increasing electric vehicle (EV) shares and fuel economy pose challenges to a fuel tax-based transportation funding scheme. This paper evaluates the fuel tax revenue impacts of such trends using Virginia as a case study. First, a county-level bivariate count model is developed using vehicle registration data in 132 counties from 2012 to 2016. Model...
Increasing electric vehicle (EV) shares and fuel economy pose challenges to a fuel tax-based transportation funding scheme. This paper evaluates such fuel tax revenue impacts using Virginia as a case study. First, a bivariate count model is developed using vehicle registration data in 132 counties from 2012 to 2016. Model results indicate strong co...
Introduction:
Cycling injury and fatality rates are on the rise, yet there exists no comprehensive database for bicycle crash injury data.
Method:
Widely used for safety analysis, police crash report datasets are automobile-oriented and widely known to under-report bicycle crashes. This research is one attempt to address gaps in bicycle data in...
This paper examines bicyclist, automobile driver, vehicle, environmental, and roadway characteristics that influence cyclist injury severity in order to determine which factors should be addressed to mitigate the worst bicyclist injuries. An ordered probit model is used to examine single bicycle-single vehicle crashes from Virginia police crash rep...
Carsharing programs provide an alternative to private vehicle ownership. Combining car-sharing programs with autonomous vehicles would improve user access to vehicles thereby removing one of the main challenges to widescale adoption of these programs. While the ability to easily move cars to meet demand would be significant for carsharing programs,...
There are natural synergies between shared autonomous vehicle (AV) fleets and electric vehicle (EV) technology, since fleets of AVs resolve the practical limitations of today’s non-autonomous EVs, including traveler range anxiety, access to charging infrastructure, and charging time management. Fleet-managed AVs relieve such concerns, managing rang...
This paper examines the life-cycle inventory impacts on energy use and greenhouse gas (GHG) emissions as a result of candidate travelers adopting carsharing in US settings. Here, households residing in relatively dense urban neighborhoods with good access to transit and traveling relatively few miles in private vehicles (roughly 10% of the U.S. pop...
The market potential of a fleet of shared autonomous electric vehicles
(SAEVs) is explored by using a multinomial logit mode choice model in
an agent-based framework and different fare settings. The mode share
of SAEVs in the simulated midsize city (modeled roughly after Austin,
Texas) is predicted to lie between 14% and 39% when the SAEVs compete...
This paper examines the impact of travel demand modeling (TDM) disaggregation techniques in the context of medium-sized communities. Specific TDM improvement strategies are evaluated for predictive power and flexibility with case studies based on the Tyler, Texas, network. Results suggest that adding time-of-day disaggregation, particularly in conj...
Electric vehicles (EVs) are predicted to increase in market share as auto manufacturers introduce more fuel efficient vehicles to meet stricter fuel economy mandates and fossil fuel costs remain unpredictable. Reflecting spatial autocorrelation while controlling for a variety of demographic and locational (e.g., built environment) attributes, the z...
Access to electric vehicle (EV) charging stations will affect EV adoption rates, use decisions, electrified mile shares, petroleum demand, and power consumption across times of day. Parking information from more than 30,000 records of personal trips in the Puget Sound, Washington, Regional Council's 2006 Household Activity Survey is used to determi...
This paper examines the influence of driving experience and habits, citation histories, vehicle ownership, and demographics on the crash risk and safety policy opinions of more than 1,000 Americans. Model results suggest that increased driver crash probability and decreased support for crash countermeasures correlate with criminal history and high...
Traffic congestion is a noted frustration for travelers around the world. Given the current environment of fiscal austerity and political tension, cost-effectiveness is a primary criterion for choosing traffic congestion solutions. Travel demand management strategies have been recognized as potentially very cost effective however implementation has...
This paper uses a heteroscedastic ordered probit model to distinguish the effects of vehicle weight, footprint and height on the severity of injuries sustained by vehicle occupants while controlling for many occupant, roadway and other characteristics. Model results suggest that the impacts of physical vehicle attributes on crash outcomes depend on...
This paper investigates the low utilization rate of the Houston QuickRide program on the I-10 and US-290 High Occupancy/Toll lanes through the analysis of its former users' survey responses. The QuickRide program allows two-occupant vehicles to travel on the HOV lane during peak periods (normally restricted to 3+ occupant vehicles) for a $2 toll.