Data

Target detection and position likelihood using an aerial image sensor

Kim, Zuwhan
Sengupta, Raja
2008

Sensor-based control is an emerging challenge in UAV applications. It is essential in a sensing task to account for sensor measurement errors when computing a target position estimate. Source of measurement error includes those in vehicle position and orientation measurements as well as algorithm failures such as missed detections or false detections. Incorporating such errors in aerial sensors is non-trival because of the camera’s perspective geometry. This paper is about a method to incorporate such errors into target position estimates and a calibration methodology to measure the error...

The Quantified Traveler: Using personal travel data to promote sustainable transport behavior

Jariyasunant, Jerald
Carrel, Andre
Ekambaram, Venkatesan
Gaker, D. J.
Kote, Thejovardhana
Sengupta, Raja
Walker, Joan L.
2011

With the advent of ubiquitous mobile sensing and self-tracking groups, travel demand researchers have a unique opportunity to combine these two developments to improve the state of the art of travel diary collection. While the use of mobile phones and the inference of travel diaries from GPS and sensor data allows for lower-cost, longer surveys, we show how the self-tracking movement can be leveraged to interest people in participating over a longer period of time. By compiling personalized feedback and statistics on participants’ travel habits during the survey, we can provide the...

The San Francisco Travel Quality Study: tracking trials and tribulations of a transit taker

Carrel, Andre
Sengupta, Raja
Walker, Joan L.
2017

In helping understand the dynamics of travel choice behavior and traveler satisfaction over time, multi-day panel data is invaluable (McFadden in Am Econ Rev 91(3): 351–378, 2001). The collection of such data has become increasingly feasible thanks to smartphones, which researchers can use to present surveys to travelers and to collect additional information through the phones’ location services and other sensors. This paper describes the design and implementation of the San Francisco Travel Quality Study, a multi-day research study conducted in autumn 2013 with 838 participants. The...

Tracking the State and Behavior of People in Response to COVID-1 19 Through the Fusion of Multiple Longitudinal Data Streams

Amine Bouzaghrane, Mohamed
Obeid, Hassan
Hayes, Drake
Chen, Minnie
Li, Meiqing
Parker, Madeleine
Rodríguez, Daniel A.
Chatman, Daniel G.
Trapenberg Frick, Karen
Sengupta, Raja
Walker, Joan
2022

The changing nature of the COVID-19 pandemic has highlighted the importance of comprehensively considering its impacts and considering changes over time. Most COVID-19 related research addresses narrowly focused research questions and is therefore limited in addressing the complexities created by the interrelated impacts of the pandemic. Such research generally makes use of only one of either 1) actively collected data such as surveys, or 2) passively collected data. While a few studies make use of both actively and passively collected data, only one other study collects it longitudinally...

Tracking the State and Behavior of People in Response to COVID-19 Through the Fusion of Multiple Longitudinal Data Streams

Bouzaghrane, Mohamed Amine
Obeid, Hassan
Hayes, Drake
Chen, Minnie
Li, Meiqing
Parker, Madeleine
Rodríguez, Daniel A.
Chatman, Daniel G.
Frick, Karen Trapenberg
Sengupta, Raja
Walker, Joan
2025

The changing nature of the COVID-19 pandemic has highlighted the importance of comprehensively considering its impacts and considering changes over time. Most COVID-19 related research addresses narrowly focused research questions and is therefore limited in addressing the complexities created by the interrelated impacts of the pandemic. Such research generally makes use of only one of either (1) actively collected data such as surveys, or (2) passively collected data from sources such as mobile phones or financial transactions. So far, only one other study collects both active and passive...

Using Smartphones to Enable Situation Awareness on Highways

Manasseh, Christian
Fallah, Yaser P.
Sengupta, Raja
Misener, James A.
2010

Motivated by the proliferation of Smartphone devices, the authors present a system architecture to enable the delivery and exchange of intelligent transportation systems (ITS) messages to Smartphones on the road. The purpose is to provide an ITS situation awareness system architecture that would enable application developers to build Smartphone applications for ITS mobility and safety. The authors present a “Slow Traffic Ahead” application as a means to validate the architecture and perform a field experiment in the San Francisco Bay Area comprised of 30 users to test the performance of...

Using Smartphones to Perform Transportation Mode Determination at the Trip Level

Parlak, Siddika
Jariyasunant, Jerald
Sengupta, Raja
2012

In this paper, the authors address the problem of determining the transportation mode at the trip level using mobile phones. The authors describe an algorithm that processes raw global positioning system (GPS) and accelerometer data to detect whether a person is standing, walking, biking, driving or taking public transit and further processes this data to determine the trip mode. This work contributes to existing research, which determines exact transportation modes at each time instant, by adding context to the mode data with trip definitions that are defined by the activity-based travel...

Collision course? The North Airfield Safety Study at Los Angeles International Airport (LAX)

Barnett, Arnold
Ball, Michael
Donohue, George
Hansen, Mark
Odoni, Amedeo
Trani, Antonio
2015

The LAX North Airfield Safety Study was undertaken by an Academic Panel consisting of the present authors, and was based in large part on a simulation that was conducted at FutureFlight Central at NASA Ames Research Center. The primary aim of the study was “to estimate as specifically as possible the level of future safety associated with several geometrical configurations of the LAX North Airfield.” This paper describes the study, and how it combined information from human-in-the-loop simulations at NASA with historical data from LAX and other US airports about runway incursions and...

Induced Travel Demand and Induced Road Investment: A Simultaneous Equation Analysis

Cervero, Robert
Hansen, Mark
2002

This paper presents simultaneous models that predict induced travel demand and induced road investment using an array of instrument variables reflecting political, environmental, and demographic influences. From a panel data set consisting of 22 years of observations for 34 California urban counties, short-run elasticities are estimated. Both the Vehicle– Miles-Travelled model and the Lane–Miles model feature good statistical fits and highly significant parameter estimates. While the research found strong reciprocal relationships between road investment and travel demand, the elasticity...

Downstream impact of flight rerouting

Ding, Wenzhe
Zhang, Yu
Hansen, Mark
2018

In this paper, we estimate the impacts of post-departure flight rerouting on times of arrival at destination airports. There are mainly two types of post-departure reroutes – opportunistic reroutes (distance-saving reroutes) and reactive reroutes (distance-increasing reroutes). To the best of our knowledge, the downstream impact of rerouting has received little attention in the existing literature; however, the benefit/harm of both kinds of reroutes might be exaggerated if their system impact is not taken into account. Thus, we developed a framework for evaluating the net effect of...