Intelligent Transportation Systems

Identifying Walking Trips Using GPS Data

Cho, GH
Rodriguez, DA
Evenson, KR
2011

This study developed and tested algorithms to identify outdoor walking trips from portable global positioning system (GPS) units in free-living conditions. Methods: The study included a calibration and a validation phase. For the calibration phase, we determined the best algorithm from 35 person-days of data. Measures of agreement regarding the daily number and duration of diary-reported and GPS-identified trips were used. In the validation phase, the best algorithm was applied to an additional and separate 136 person-days of diary and GPS data. Results: The preferred algorithm in the...

Improving Estimates of Travel Activity and AIir Pollution Exposure Through Ubiquitous Sensing Technologies

Nazelle, A De
Seto, E
Donaire, D
Mendez, M
Matamala, J
Portella, M
Rodriguez, D
Nieuwenhuijsen, M
Jerrett, M
2011
Travel activity may have important influences on health, potentially contributing meaningfully to both physical activity (PA; walking and cycling) and inhaled air pollution. Ubiquitous sensing technology is a promising innovation to track locations of travel activity and associated levels of energy expenditure. We present results of a pilot study testing the use and performance of Calfit, a novel smart-phone based software that continuously records geo-positioning and PA estimated from an accelerometer integrated into Android cell-phone technology. Methods: We equipped 36 volunteers with an...

Out and About: Association of the Built Environment with Physical Activity Behaviors of Adolescent Females

Rodriguez, DA
Cho, GH
Evenson, KR
Conway, TL
Cohen, D
Ghosh-Dastidar, B
Pickrel, J
Veblen-Mortenson, S
Lytle, L
2012

Locational data, logged on portable GPS units and matched with accelerometer data, was used to examine associations of the built environment with physical activity and sedentary behaviors of adolescent females. In a sample of 293 adolescent females aged 15 to 18 years old in Minneapolis and San Diego, the built environment around each GPS point and its corresponding sedentary, light, and moderate-to-vigorous intensity physical activity was examined using random intercept multinomial logistic regression models. The odds of higher physical activity intensity (3-level outcome: sedentary...

Ten Strategies for Freeway Congestion Mitigation with Advanced Technologies

Daganzo, Carlos F.
Laval, Jorge
Munoz, Juan Carlos
2002

This report presents ten strategies for improving freeway performance that have become feasible with the advent of new software and hardware technologies for traffic control. Most of the strategies can be applied with advanced implementations of existing hardware. The strategies have in common that they can be rigorously tested. heir measures of performance can be reliably obtained and do not depend on the accuracy of data- hungry, large-scale models.

Longitudinal Control Development For IVHS Fully Automated And Semi-automated Systems: Phase II

Hedrick, J. K.
Garg, V.
Gerdes, J. C.
Maciuca, D. B.
Swaroop, D.
1996

This report studies performance issues in Automated Vehicle Control Systems (AVCS). Specifically, it addresses the automatic braking controller design issues, effects of braking on Intelligent Vehicle Highway Systems (IVHS) lane capacity, performance of platoons with various information structures, and fault detection filter design for AVCS.

Engaging the International Community: Research on Intelligent Transportation Systems (ITS) Applications to Improve Environmental Performance

Shladover, Steven
Barth, Matthew J
Zhang, Wei-Bin
2011

This project was proposed to build on the exposure that the authors of this report have had during the past two years to the thinking of the Japanese and European thought leaders about how Intelligent Transportation System (ITS) can contribute toward meeting environmental goals, especially for reducing CO2.

The ISTEA/ITS Connection In California: The State Of The Relationship And Opportunities For Productive And Beneficial Linkages

Miller, Mark
Jia, Wenyu
1998

This report describes research which had three objectives: 1) investigate the current state of California's implementation of the Intermodal Surface Transportation Efficiency Act (ISTEA) with respect to Intelligent Transportation Systems (ITS), 2) assess the extent to which ITS has been integrated within the State's transportation planning process, and 3) recommend opportunities for linkages between ISTEA and ITS that have not yet been recognized. A literature search was first conduced which studied the key features of ISTEA, specific ITS-related issues, the institutional environment, and...

Identifying Walking Trips from GPS and Accelerometer Data in Adolescent Females

Rodriguez, D
Cho, GH
Elder, JP
Conway, TL
Evenson, KR
2012

Studies that have combined accelerometers and global positioning systems (GPS) to identify walking have done so in carefully controlled conditions. This study tested algorithms for identifying walking trips from accelerometer and GPS data in free-living conditions. The study also assessed the accuracy of the locations where walking occurred compared with what participants reported in a diary. A convenience sample of high school females was recruited (N = 42) in 2007. Participants wore a GPS unit and an accelerometer, and recorded their out-of-school travel for 6 days. Split-sample...

Models of Vehicular Collision: Development and Simulation with Emphasis on Safety V: MEDUSA: Theory, Examples, User's Manual, Programmer's Guide and Code

O'Reilly, Oliver M.
Papadopoulos, Panayiotis
Lo, Gwo-Jeng
Varadi, Peter C.
1999

This document constitutes a final report for MOU 39. It contains a User's Manual, Programmer's Guide, source code and underlying theory for the program MEDUSA. This program is capable of simulating both the normative driving dynamics and collision dynamics of an arbitrary number of vehicles. Its range of validity lies in the assumed nature of the vehicular collision, and it is recommended for use in studying low relative velocity impact scenarios at large time-scales. Keywords: IVHS America, Vehicle Dynamics, Collision Dynamics, Safety, computer Simluation, Animal and Simulation; A...

Digital Implementation of Adaptive Control Algorithms for MEMS Gyroscopes

Park, Sungsu
Horowitz, Roberto
Tan, Chin-Woo
2002

In this report, we present a hybrid discrete/ continuous time version of the observer-based adaptive control system for MEMS gyroscopes developed in [8], which can be readily implemented using digital processors. The control algorithm considered in this report is not fully a discrete time controller, since only the feedback control, parameter adaptation algorithms and feedforward control law are implemented in discrete time, while the velocity observer is still implemented in continuous time. A stochastic analysis of this algorithm is developed and it shows that the estimates of the...