Environment

Dissecting Lightning Strike Hazard Impact Patterns to National Airspace System Facilities in the Contiguous United States

He, Yiyi
Yue, Xiangyu
Lindbergh, Sarah
Gao, Jianxi
Graves, Chuck
Rakas, Jasenka
2022

Lightning strikes pose a severe threat to the United States (US) National Airspace System (NAS). Although the US Federal Aviation Administration (FAA) implements lightning protection practices and procedures to protect personnel, electronic equipment, and structures within the NAS, many lightning-induced outages still occur. To date we found that most research on lightning-induced facility outages has focused on understanding the physical processes of lightning strike effects on aircraft and airport ramp operations. Very little research has been done on examining the overall patterns and...

Economic Impact of a Lightning Strike–Induced Outage of Air Traffic Control Tower: Case Study of Baltimore–Washington International Airport

Ding, Wenzhe
Rakas, Jasenka
2015

This research investigates how lightning strike–induced outages of airport infrastructure and facilities affect airport performance from an economic perspective, using Baltimore (Maryland)–Washington (D.C.) Thurgood Marshall International (BWI) Airport as a case study. On September 12, 2013, lightning struck within 300 m of the air traffic control (ATC) tower at BWI, causing injury and ATC tower and airport closures. The study findings reveal that the economic losses of the outage-related delays from that single event were almost five times higher than the ATC tower refurbishment that was...

Implications of Wind Changes and Cross Wind Hazard Exposures at California Airports for Regional Air Mobility

Rakas, Jasenka
Hu, Yingjie
Lindbergh, Sarah
2024

California has a large number of public airports, including single-runway general aviation airports and small commercial airports. Because of anticipated changes in future temperature and precipitation in California (CA) and their effect on airports, our study raises a related question: will airports in CA experience any significant changes in wind direction and speed? This issue is especially important to address at single-runway airports where the occurrence of crosswinds exceed 10.5kn. Under such crosswind conditions, it is not safe for smaller/lighter aircraft to land and take-off....

California Democrats propose relaxed emissions rules amid gas price crisis

July 23, 2025

CBS News_Elkind

ITS affiliate, Ethan Elkind, director of the climate program at the University of California, Berkeley School of Law, discussed California Democrats propose relaxed emissions rules amid gas price crisis with CBS News:...

Quantification of Weather Influences on Freeway Bottlenecks

Seeherman, Joshua
Skabardonis, Alexander
Transportation Research Board
2013

Weather is a major source of non-recurring delay on freeways within the United States. How weather affects areas of daily recurring delay, particularly freeway bottlenecks, has not been thoroughly researched. A type of freeway bottleneck in the form of a lane drop was studied across two winters at a site of daily recurring congestion. This bottleneck was located in Pittsburg, California. Queue discharge flow was compared between rainy days and clear days either one week before or after the rainy event. Discharge flows during rainy events dropped by an average of 11% and this difference was...

Prediction of Vehicle Activity for Emissions Estimation Under Oversaturated Conditions Along Signalized Arterials

Skabardonis, Alexander
Geroliminis, Nikolas
Christofa, Eleni
2013

The traditional methodology for estimating vehicle emissions based on vehicle miles traveled and average speed is not reliable because it does not consider the effects of congestion, control devices, and driving mode (cruise, acceleration, deceleration, and idle). The authors developed an analytical model to predict vehicle activity on signalized arterials with emphasis on oversaturated traffic conditions. The model depends only on loop detector data and signal settings as inputs and provides estimates of the time spent in each driving mode, which consequently leads to more accurate...

Observed and simulated traffic impacts from the 2013 Bay Area Rapid Transit strike

Moylan, Emily
Foti, Fletcher
Skabardonis, Alexander
2016

Despite high costs, many cities build public transit to address regional equity, environmental and economic goals. Although public transit accounts for a minority of trips (∼5%), the impact is widely felt when service is suspended during a strike through excess road demand and slower journeys. In 2013, Bay Area Rapid Transit (BART) workers participated in two brief strikes, and the resulting traffic conditions illustrate the value of transit to drivers in the San Francisco Bay Area region. This paper tests the impact of rail transit service interruption on freeway traffic conditions using...

Impacts of Weather on Traffic Flow Characteristics of Urban Freeways in Istanbul

Akin, Darcin
Sisiopiku, Virginia P
Skabardonis, Alexander
2011

Speed-flow relationships have been established for different free-flow speeds on urban freeways. However, there have been few research efforts relating real-time traffic flow parameters and weather conditions for different levels of heavy vehicle traffic. This study aims at establishing relationships between speed and volume in freeway sections using Remote Traffic Microwave Sensor (RTMS) data as a function of weather conditions. Historical weather and RTMS detector data (i.e., volume and speed) from two highway corridors in the Istanbul metropolitan area are used for this purpose....

Impact of traffic states on freeway crash involvement rates

Yeo, Hwasoo
Jang, Kitae
Skabardonis, Alexander
Kang, Seungmo
2013

Freeway traffic accidents are complicated events that are influenced by multiple factors including roadway geometry, drivers' behavior, traffic conditions and environmental factors. Among the various factors, crash occurrence on freeways is supposed to be strongly influenced by the traffic states representing driving situations that are changed by road geometry and cause the change of drivers' behavior. This paper proposes a methodology to investigate the relationship between traffic states and crash involvements on the freeway. First, the authors defined section-based traffic states: free...

Impact of Adverse Weather on Freeway Bottleneck Performance

Seeherman, Joshua
Skabardonis, Alexander
2020

Congestion on freeways occurs when demand exceeds the available capacity. Common causes of recurring congestion, also known as freeway bottlenecks, include lane drops, on-ramp merges, and weaving sections. Adverse weather can reduce the maximum queue discharge flow, but this effect has not been systematically investigated. This research examined the relationship between discharge flow and weather characteristics including rainfall intensity, wind speed, and visibility. Queue discharge rates at four isolated merge bottlenecks were measured using an established methodology of cumulative...