Environment

Sensor-Friendly Freeways: Investigation of Progressive Roadway Changes to Facilitate Deployment of AHS

Misener, James A.
Griffiths, Paul
Johnson, Lee
Segal, Andy
2001

Intelligent "driver assistance" systems which utilize in-vehicle forward-looking sensors can be supplemented by vehicle-vehicle and vehicle-highway cooperative elements to comprise a "sensor-friendly" highway environment that would enhance the operational efficiency, and ultimately, the safety benefits of these systems. In our research, we have identified the current limitations of autonomous sensing systems in target/background discrimination with cluttered highways. Based upon this, and by limiting ourselves to "sensed" (and not wireless) systems, we have conceived relatively inexpensive...

Evaluation of Wet Weather Accident Causation Criteria

Oh, Soon Mi, MS
Ragland, David R., PhD
Chan, Ching-Yao, PhD
2010

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP).The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the notable...

Intelligent Diagnosis Based On Validated And Fused Data For Relilability And Safety Enhancement Of Automated Vehicles In An IVHS

Agogino, Alice
Chao, Susan
Goebel, Kai
Alag, Satnam
Cammon, Bradly
Wang, Jiangxin
1998

Vehicles in an IVHS system rely heavily on information obtained from sensors. So far, most control systems make the implicit assumption that sensor information is always correct. However, in reality, sensor information is always corrupted to some degree by noise which varies with operating conditions, environmental conditions, and other factors. In addition, sensors can fail due to a variety of reasons. To overcome these shortcomings, sensor validation is needed to assess the integrity of the sensor information and adjust or correct as appropriate. In the presence of redundant information...

Rapid Prototyping Of Advanced Driver Interface Systems

Massa, Laura J.
Mendel, Max B.
1993

This report describes a computer environment for rapidly prototyping user interfaces for advanced driver information systems (ADIS).

Health and Environmental Co-Benefits of City Urban Form in Latin America: An Ecological Study

Avila-Palencia, I
Sánchez, BN
Rodríguez
Perez-Ferrer
Miranda, J
Gouveia, N
Bilal, U
Useche, A
Wilches-Mogollon, M
Moore, K
Sarmiento, O
Roux, AV Diez
2022
We investigated the association of urban landscape profiles with health and environmental outcomes, and whether those profiles are linked to environmental and health co-benefits. In this ecological study, we used data from 208 cities in 8 Latin American countries of the SALud URBana en América Latina (SALURBAL) project. Four urban landscape profiles were defined with metrics for the fragmentation, isolation, and shape of patches (contiguous area of urban development). Four environmental measures (lack of greenness, PM2.5, NO2, and carbon footprint), two...

The Dynamics of the California Electric Grid Mix and Electric Vehicle Emission Factors

Zhang, Xingrui
Martin, Elliot
Shaheen, Susan
2025

Electric vehicle (EV) emissions occur when a vehicle is charged and are based on the mix of power sources used during that period. The rapid growth of solar and wind energy has introduced a high degree of variability in the emissions of the grid for both diurnal and annual periodicities. Growth in solar energy has been particularly prominent in California. Using grid mix data spanning April 2018 to April 2023 from the California Independent System Operator (CAISO) and power source emission factors, we evaluate the grid mix at 5 min intervals and estimate the emission factors based on the...

Environmental Impacts of Transportation Network Company (TNC)/Ride-Hailing Services: Evaluating Net Vehicle Miles Traveled and Greenhouse Gas Emission Impacts within San Francisco, Los Angeles, and Washington, D.C. Using Survey and Activity Data

Martin, Elliot
Shaheen, Susan
Wolfe, Brooke
2024

Transportation Network Companies (TNCs) play a prominent role in mobility within cities across the globe. However, their activity has impacts on vehicle miles traveled (VMT) and greenhouse gas (GHG) emissions. This study quantifies the change in personal vehicle ownership and total miles driven by TNC drivers in three metropolitan areas: San Francisco, CA; Los Angeles, CA; and Washington, D.C. The data sources for this analysis comprise two surveys, one for TNC passengers (N = 8630) and one for TNC drivers (N = 5034), in addition to data provided by the TNC operators Uber and Lyft. The...

Can Electric Vehicle Carsharing Bridge the Green Divide? A Study of BlueLA’s Environmental Impacts among Underserved Communities and the Broader Population

Yassine, Ziad
Martin, Elliot W.
Shaheen, Susan A.
2024

This study aims to evaluate the potential of electric vehicle (EV) carsharing services to address social and environmental disparities in urban transportation through an evaluation of BlueLA, a one-way station-based carsharing service in Los Angeles, California. BlueLA provides a clean and affordable mobility option in underserved communities that face significant air quality burdens and have historically been excluded from environmental benefits. By incorporating BlueLA trip activity data from January 2021 to December 2022 (n = 59,112 trips) and an online user survey implemented in early...

More Needs to Be Done to Lower Costs for Ridehailing Drivers to Shift to Electric Vehicles

Shaheen, Susan
Martin, Elliot
Ju, Mengying
2025

Transportation network companies (TNCs) have played an increasingly prominent role providing on-demand mobility for consumers across California. The California Public Utilities Commission (CPUC) and the California Air Resources Board (CARB) have adopted and are implementing SB 1014 (Clean Miles Standard), which establishes an annual increase in the percent of zero-emission passenger miles traveled and greenhouse (GHG) emission reduction targets for TNCs. This regulation requires TNC drivers to acquire and operate an electric vehicle (EV).

Highway Electrification And Automation Technologies - Regional Impacts Analysis Project: Executive Summary

Scag
Path
1993

The Highway Electrification and Automation Technologies Regional Impacts Analysis Project (HE&A) addressed the transportation-related problems of freeway congestion, air pollution, and dependence on fossil fuels in southern California. The impacts of roadway electrification and highway automation were investigated to determine to what extent these advanced technologies could alleviate these problems. For the highway electrification technology, utility, environmental, and economic impacts were also studied. The feasibility of implementing one or more demonstrations in the six-county...