conference paper
published journal article
conference paper
Section-related or link-based data can arguably provide reliable and accurate inputs for traffic surveillance and performance measurement systems. To obtain section-related data, vehicle reidentification plays an important role since section performance measurements can be generated easily via a vehicle reidentification system. Among vehicle reidentification systems, ILD (inductive loop detector) based systems are cost-effective because the ILDs are largely installed in the field (with fewer market penetration concerns), and are essentially anonymous systems with few if any privacy concerns. Accordingly, the authors recently developed an algorithm, RTREID-2, using inductive loop signature-based methods for vehicle reidentification (ILD-VReID) and which was dedicated to meet the needs for real-time implementation and section performance measurement. RTREID-2 was developed by utilizing a Piecewise Slope Rate (PSR) approach to transform the raw vehicle signatures obtained from square loops (only). This paper reports the results of a 6.2 mile freeway corridor implementation of RTREID-2 under congested morning peak-period conditions. Although RTREID-2 has been designed for real-time operation, this initial corridor investigation was conducted off-line. The corridor contained mostly round inductive loop sensors with some square loops, providing an opportunity to assess the applicability and transferability of RTREID-2 to homogeneous and heterogeneous loop sensor systems. A freeway corridor and section travel time and speed analysis was conducted and excellent results were obtained, compared with GPS measurements from control vehicles. The results suggest that RTREID-2 has the potential to be implemented successfully in a congested freeway corridor, utilizing either or both round or square inductive loop sensors.
conference paper
Research has shown that parental attitudes are a significant predictor of childrenâ??s active commuting (walking or biking) to school. However, the impact of parental gender on parental attitudes, and the link between parental attitudes and the gender gap in parental escort behavior have not received much attention. This paper examines these questions by applying discrete choice models to California data from the 2009 National Household Travel Survey while controlling for a wide range of variables characterizing parents, their children, households, schools, and the local built environment. Our results show that mothers are more likely to have higher concerns about traffic volume and speed, which in turn reduces the likelihood that their children will walk or bike to school. Moreover, parental attitudes (especially mothersâ?? attitudes) significantly influence parental escort behavior, although their ability to explain the within-household gender escort gap is limited. However, the escort duties of mothers are reduced when they bike more often, which suggests that more biking by parents encourages children to actively commute to school. Finally, while distance to school and several land use measures (e.g., population density, urbanization level, and percentage of renters) are statistically significant, the impact of an objective measure of walkability is quite small. These results suggest that interventions targeting an increase in childrenâ??s walking and biking to school should focus on the concerns of mothers, especially as they relate to traffic characteristics.
policy brief
Tractor-trailers dominate the truck cargo industry. Between 1990 and 2010, this industry grew significantly; vehicle miles traveled increased 87 percent and ton-miles increased by 47 percent. While the growth of trucking miles and tonmiles is a positive indicator of economic transformation and expansion, the trucking sector also produces negative externalities, including but not limited to pavement damage. Pavement damage is closely tied to vehicle weight, which is a product of private market decisions driven by the cost of delivery per ton and the frequency of delivery. Understanding the interplay between fuel cost and private sector decisions on truck dispatch (i.e., frequency and load of trucks) is key to understanding infrastructure damage.
policy brief |
Aug 2020
research report |
Jun 2017
conference paper
Inter-vehicle communication is a promising way to share and disseminate real-time and nearby safety information on the road. However, several pressing open questions require solutions in order to achieve high reliability and efficiency with these systems. Further, previous studies show that mobility model can significantly influence the communication performance in vehicular networks. In this paper, we analyze communication in stop-and-go waves and propose a method to optimize an important network parameter, the transmission range, based on traffic pattern measures. Our findings suggest a transmission range adjustment scheme that achieves high reliability by considering network coverage and packet reception rates.
book/book chapter
working paper
This research deals with demand for automobiles and light-duty and medium-duty trucks. Planners concerned with energy consumption, air quality and the provision of transportation facilities must have dependable forecasts of vehicle ownership and use from both the residential (personal-use vehicle) sectors and the fleet (commercial and governmental) sectors. As long as vehicles evolved slowly, it was possible to base such forecasts on extrapolations of observed demand. However, in an era of increasing environmental awareness, mandated in part by the Clean Air Act Amendments (US EPA, 1990), government agencies are now concerned with promoting clean-fuel vehicles; vehicle manufacturers are faced with designing and marketing clean-fuel vehicles; and suppliers of fuels other than gasoline must plan infrastructure and pricing policies.
conference paper
Traffic flow sensors are crucial for transportation management and planning, but their accuracy is often compromised by various malfunctions. This study develops a robust framework for detecting traffic sensor malfunctions by leveraging lane-to-lane traffic correlations, addressing limitations of previous methods that focused solely on individual sensor performance. We introduce the coefficient of variation (CV) as a measure of lane-to-lane correlation, calculated as the ratio of standard deviation to mean of traffic measurements (flow rate or density) across lanes. Using the NGSIM dataset with detailed vehicle trajectories, we establish a range of CV values for accurately functioning sensors through hypothesis testing, based on Edie’s generalized definition of traffic variables. We then apply this CV range to identify malfunctioning loop detectors in the California PeMS dataset on State Route 91. This is based on the assumption that lane-to-lane correlations should fall within a specific range for correlated general-purpose lanes. In this dataset, density is calculated by dividing occupancy by the length of a loop detector and adding the vehicle length. Our methodology enhances the accuracy of detecting traffic sensor malfunctions, contributing to improved transportation management and planning. Future work could explore applying this approach to different road types and traffic conditions, including lanes with special purposes.
conference paper
An emerging trend for vehicle transportation is the use of car sharing systems. These change vehicle operations from an autonomous to a dynamic model supporting multiple users and multiple passengers. The authors investigate the network communications and conditions necessary to operate an efficient and cost-effective car sharing fleet system. Further, the authors explored the feasibility and challenges of using Wi-Fi as the communications medium for operating such car sharing systems in metropolitan locations. The preliminary study indicates that Wi-Fi connectivity works well while vehicles are traveling between zero and twenty miles per hour, and is therefore a feasible communication technology in urban areas where vehicles regularly travel at slow speeds and spend time at rest.