Shashi Nambisan - Profile on Academia.edu (original) (raw)

Papers by Shashi Nambisan

An MPEC Model for the Optimal Contraflow Operation Problem with User Equilibrium Constraints

10.1061/40799(213)134Applications of Advanced Technology in Transportation - Proceedings of the N... more 10.1061/40799(213)134Applications of Advanced Technology in Transportation - Proceedings of the Ninth International Conference on Applications of Advanced Technology in Transportation834-83

Casual Factors and Apparent Role of Turning Movement on Crashes in Clark County, Nevada

Clark County, Nevada is one of the fastest growing metropolitan areas in the United States. The r... more Clark County, Nevada is one of the fastest growing metropolitan areas in the United States. The region has observed more than 6% annual growth in population over the last decade. This has a significant impact on the growth in travel demand and the economy of the region. In turn, there is a need to meet this growing demand, to improve traffic safety, and enhance the quality of life in the region. Analyzing the right aspects is very critical for guiding data activities, implementing traffic safety and injury prevention strategies and understanding if they work. The objective of this paper is to identify the most pressing traffic safety issues to develop countermeasure programs so as to address the needs. This is based on crashes reported during 1996, 1997 and 1998.

An Evaluation of the Effectiveness of an In-pavement Flashing Light System

Abstract: Strategies used to enhance pedestrian safety on roadways include the in-pavement flashi... more Abstract: Strategies used to enhance pedestrian safety on roadways include the in-pavement flashing light system. These lights are alert both motorists and pedestrians. While the system has been deployed in some locations, limited documentation exists in the ...

Evaluation of Side Swipe Crashes at Triple and Dual Left Turn Lanes in Las Vegas, Nevada

In 1989, the Las Vegas, Nevada, metropolitan area installed its first triple left-turn lane desig... more In 1989, the Las Vegas, Nevada, metropolitan area installed its first triple left-turn lane design at a signalized urban intersection. Since then, three other intersection approaches have had similar triple left-turn configurations installed. One of the major concerns pertaining to traffic operations in these turn lanes is the potential for sideswipe crashes. A comparative analysis of the safety performance of traffic operations at intersections as a whole, and sideswipe crashes at intersections and sideswipe crashes during left-turn movements at triple and dual left-turn lanes is presented in this paper. A database of all accident reports filed by law enforcement officers since 1987 was used to evaluate the total crashes, all sideswipe crashes, and sideswipe crashes for the left-turn movements at a selected group of intersections in the Las Vegas metropolitan area. A preliminary analysis of the data shows sideswipe crashes account for a very small portion of the total crashes that occur at intersections. Further, left-turn sideswipe crashes account for a very small portion of all sideswipe crashes at dual left-turn lanes, while those at triple left-turn lanes account for 50% of the sideswipe crashes at the intersection. The geometric design of the intersections, including accounting for potential bottlenecks such as bus stops at the far side of the intersection, appear to be important factors that need to be considered. These findings are significant for those communities considering installation of triple left-turn lanes.

An Assessment of Child Restraint System Misuse in the United States

Transportation Research Board 97th Annual MeetingTransportation Research Board, 2018

Impacts on Traffic Citations by Advanced Driver Assistance Systems

Analysis of Effects of CAFE Standards, Hybrid and Alternative Fuel Vehicles on Fuel Tax Revenues

Transportation Research Board 90th Annual MeetingTransportation Research Board, 2011

Various policy options including Corporate Average Fuel Efficiency (CAFE) are forcing auto manufa... more Various policy options including Corporate Average Fuel Efficiency (CAFE) are forcing auto manufacturers and auto distributors to improve the fuel efficiency of vehicles significantly over the next decade. On the other hand, improved automotive technologies and higher gasoline fuel prices enable better alternative fuel vehicles, including hybrid vehicles and electric cars. This research evaluates the impacts of CAFE regulations in automobile and light truck fleet fuel economies, as well as impacts of hybrid vehicles (HV) and alternative fuel vehicles (AFV) in the fleet, on gasoline tax based revenues. The New Sales Survivability (NSS) model, along with new vehicle sales data and vehicle survivability data from 1980 to 2005 were used to estimate the fleet mix, vehicle miles of travel (VMT) by fleet mix, and revenue projections through the year 2025. Five scenarios were considered to analyze the impacts of CAFE regulations and introduction of hybrid vehicles and AFV on fuel consumption and hence on fuel tax based revenues for highway revenues. The results show that CAFE regulation alone is expected reduce the fuel tax based revenue by over 21 percent in the year 2025. Similarly, introduction of HV and AFV along with CAFE regulations are expected to reduce fuel tax based revenues by over 31 percent and 37 percent respectively in the year 2025. This paper shows the significance of considering the impacts of new regulations and technological improvements in estimating future fuel based revenues. The revenue estimated in this paper is much lower than the estimates developed by previous studies. This shows that modifications to the existing system of highway financing would be required much earlier than anticipated.

交差点間の中間の単路(midblock)における横断歩行者の安全評価の方法論

Transportation Research Record, 2003

Transportation Research Board 95th Annual MeetingTransportation Research Board, 2016

UT). Since 1989, he has led efforts on more than 165 research, education, and outreach projects t... more UT). Since 1989, he has led efforts on more than 165 research, education, and outreach projects that have addressed local, statewide, regional and national issues in transportation and infrastructure systems management related to policy, planning, operations, safety, and risk analysis. He has authored or co-authored more than 125 peer reviewed journal and conference publications. Along with his students and colleagues, he has made over 230 technical presentations at international, national, and regional conferences and at universities. One of Professor Nambisan's passions is the development of the future workforce, including efforts at the pre-college level. He enjoys working with students. For his contributions as an educator, researcher, and leader, Professor Nambisan has received several awards and honors. Among the awards and honors he has received is a proclamation by the Governor of Nevada designating January 31, 2007 as the "Professor Shashi Nambisan Day" in recognition of his leadership role in and contributions to enhancing transportation safety.

Future transportation, Aug 2, 2023

Connected and Automated Vehicles (CAVs) offer the potential to improve roadway capacity and safet... more Connected and Automated Vehicles (CAVs) offer the potential to improve roadway capacity and safety. Thus, improving road infrastructure condition could be prioritized to eliminate further degradation of the transportation infrastructure. In order to foster the adoption of CAVs, incentives can be used; but there is a need to identify what type of incentive would be most effective. To identify effective incentive types, this study uses electric vehicles (EV) and hybrid vehicles as a surrogate to CAVs because of the similarities in obstacles faced for wider adoption. This study then provides some recommendations by examining incentives offered in 15 different countries and by reviewing the literature on the effectiveness of incentive types.

The 2020 Vision of Air Transportation

The Impacts of Click It-Or-Ticket Campaign and Saturation Patrol Interventions on Nighttime Seat Belt Usage

Transportation Research Board 96th Annual MeetingTransportation Research Board, 2017

Case studies on transport policy, Sep 1, 2020

Seatbelt laws are deemed effective at increasing seatbelt use, consequently, reducing fatalities ... more Seatbelt laws are deemed effective at increasing seatbelt use, consequently, reducing fatalities associated with motor vehicle crashes in the United States. Previous studies have provided significant insights about the effectiveness of seatbelt laws, however, studies exploring passenger seatbelt use accounting for the variations in seatbelt laws are not well documented in the literature. Seatbelt laws vary by whether they cover front-seat occupants only or include rear-seat passengers as well. The primary objective of this study was to investigate the differences in adult seatbelt compliance rate based on six categories of seatbelt laws in the United States using crash data. In this present study, six categories of seatbelt laws are considered ranging from no seatbelt law to primary seatbelt law covering all vehicle occupants. Using Tukey-type multiple comparison test, a positive relationship between seatbelt laws and adult seatbelt use was found. Specifically, states with stricter seatbelt laws, that is primary law for all front-and rear-seat occupants, exhibit higher seatbelt compliance rate than those with less strict (partial primary/secondary laws) or no seatbelt laws. Given the significant differences in adult seatbelt use based on our study design (using six categories of seatbelt laws), the analysis support that if states upgrade their seatbelt laws from no/secondary laws to primary laws covering all vehicle occupants, there likely will be positive impacts on adult seatbelt use. The findings in this study are to inform and support decision policies and intervention strategies that are effective at promoting safety for motor vehicle occupants.

Seatbelt Use among Vehicle Occupants in Fatal Crashes in the United States: Does Vehicle Type and Age Affect Injury Outcome?

Transportation Research Board 100th Annual MeetingTransportation Research BoardTransportation Research Board, 2021

Are Enforcement Strategies Effective in Increasing Nighttime Seat Belt Use? Evidence from a Large-Scale Before–After Observational Study

Transportation Research Board 97th Annual MeetingTransportation Research Board, 2018

Preparing tomorrow's transportation workforce : a Midwest summit

Journal of Loss Prevention in The Process Industries, Mar 1, 2021

The transportation of natural gas often relies on pipelines which require constant monitoring and... more The transportation of natural gas often relies on pipelines which require constant monitoring and regular maintenance to prevent spills or leaks. Pipeline incidents could pose a huge adverse impact on people, the environment, and society. Numerous efforts have been invested to identify contributing factors to pipeline incidents so that countermeasures could be developed to proactively prevent some incidents and reduce incident severities or impacts. However, the countermeasures may need to vary for different incidents due to the potential heterogeneity between incidents, and such heterogeneity is likely related to the geology, weather, and built environment which vary across space and time domain. The objective of this study is to revisit the correlates of pipeline incidents, focusing on the spatial and temporal patterns of the correlations between natural gas pipeline incident severity and contributing factors. This study leveraged an integrated spatio-temporal modeling approach, namely the Geographically and Temporally Weighted Ordered Logistic Regression (GTWOLR) to model the natural gas pipeline incident report data (2010-2019) from the U.S. Pipeline and Hazardous Material Safety Administration. Text mining was performed to extract additional information from the narratives in reports. Results show several factors have significant spatiotemporally varying correlations with the pipeline incident severity, and these factors include excavation damage, gas explosion, iron pipes, longer incident response time, and longer pipe lifetime. Findings from this study are valuable for pipeline operators, end-users, responders to jointly develop localized strategies to maintain the natural gas distribution system. More implications are discussed in the paper.

Analyzing injury crashes using random-parameter bivariate regression models

Transportmetrica, May 10, 2016

ABSTRACT This paper proposes a random-parameter bivariate zero-inflated negative binomial (RBZINB... more ABSTRACT This paper proposes a random-parameter bivariate zero-inflated negative binomial (RBZINB) regression model for analyzing the effects of investigated variables on crash frequencies. A Bayesian approach is employed as the estimation method, which has the strength of accounting for the uncertainties related to models and parameter values. The modeling framework has been applied to the bivariate injury crash counts obtained from 1000 intersections in Tennessee over a five-year period. The results reveal that the proposed RBZINB model outperforms other investigated models and provides a superior fit. The proposed RBZINB model is useful in gaining new insights into how crash occurrences are influenced by the risk factors. In addition, the empirical studies show that the proposed RBZINB model has a smaller prediction bias and variance, as well as more accurate coverage probability in estimating model parameters and crash-free probabilities.

An Analysis of the Effectiveness of Pedestrian Countdown Signals Based on Pedestrian Actions

2006 ITE Annual Meeting and Exhibit Compendium of Technical PapersInstitute of Transportation Engineers (ITE), 2006

This paper describes how pedestrian countdown signals have been deployed over the past few years ... more This paper describes how pedestrian countdown signals have been deployed over the past few years in the Las Vegas Metropolitan Area in order to help enhance pedestrian safety at crosswalks. The paper summarizes the efforts of a study to evaluate the effectiveness of such signals. The effectiveness was evaluated by considering pedestrian actions at signalized locations in the Las Vegas Metropolitan area. A before-and-after study was performed for this purpose. The “before” condition data were collected immediately prior to installation of the countdown signals, and the “after” condition data were collected several months after the installation of the signals. The measures of effectiveness (MOEs) identified to evaluate the effectiveness of these installations include the following: pedestrian-vehicle conflicts, pedestrians in a crosswalk during the flashing DON’T WALK, pedestrians trapped in the middle of crossing, pedestrians in the second half of the road during flashing DON’T WALK, pedestrians who started crossing during DON’T WALK, and pedestrians in the crosswalk at the end of all red. Results of the analyses of the data indicate that the use of pedestrian countdown signals led to a decrease in percentage of conflicts, pedestrians in a crosswalk during flashing DON’T WALK, pedestrians who started crossing during DON’T WALK, and pedestrians in a crosswalk at the end of all red time. These indicate that the countdown signals were effective in enhancing pedestrian safety.

Model Linkages and Gis Applications for Air Quality Planning

This paper documents the development of a geographic information system (GIS) based system to sup... more This paper documents the development of a geographic information system (GIS) based system to support evaluation of transportation policies related to air quality planning--specifically with respect to carbon monoxide (CO) concentrations. The system provides a mechanism to relate the travel demand modeling process with air quality analysis. A case study of the Las Vegas valley demonstrates the development and application of the system. Since this area has been designated by the Environmental Protection Agency to be in non-attainment of the National Ambient Air Quality Standards for CO, a State Implementation Plan (SIP) must be developed to identify a plan for attaining conformity with those standards. Transportation sources of emissions account for a vast majority of the CO emissions in the Las Vegas valley. Thus, the development of a SIP requires explicit consideration of travel demand, vehicular emissions, and dispersion models. This paper describes the linking of tools and models required for this purpose. The system facilitates linking these models and thus minimizes duplication of resources, especially pertaining to data requirements. Due to the powerful capabilities afforded by a GIS to manage, manipulate, analyze, and display spatial data and due to the spatial nature of data required to support the analysis and modeling processes described here, a GIS environment was a logical choice for developing the model linkages. The system permits evaluation of the impact or effectiveness of policies ranging from land use planning/zoning alternatives to travel demand management strategies on CO concentrations in the valley. Menu driven interfaces are developed to enhance the ease of use of the system. The paper also addresses technological problems and institutional issues encountered during the development of the system.