Search

Drones are becoming indispensable in emergency search and rescue (SAR), particularly in intricate urban areas where rapid and accurate response is crucial. This study addresses the pressing need for enhancing drone navigation in such complex, dynamic urban environments, where obstacles like building layouts and varying wind conditions create unique challenges. Particularly, the need for adapting drone autonomous navigation in correspondence with dynamic wind conditions in urban settings is emphasized because it is important for drones to avoid loss of control or crashes during SAR. This paper introduces a pioneering method integrating multiobjective reinforcement learning (MORL) with a convolutional autoencoder to train autonomous drones in comprehending and reacting to aerodynamic features in urban SAR. MORL enables the drone to optimize multiple goals, whereas the convolutional autoencoder generates synthetic wind simulations with a substantially lower computation cost compared to traditional computational fluid dynamics (CFD) simulations. A unique data transfer structure is also proposed, which fosters a seamless integration of perception and decision-making between machine learning (ML) and reinforcement learning (RL) components. This approach uses imagery data, specific to building layouts, allowing the drone to autonomously formulate policies, prioritize navigation decisions, optimize paths, and mitigate the impact of wind, all while negating the necessity for conventional aerodynamic force sensors. The method was validated with a model of New York City, offering substantial implications for enhancing automation algorithms in urban SAR. This innovation enables the possibility of more efficient, precise, and timely drone SAR operations within intricate urban landscapes. [ABSTRACT FROM AUTHOR]

This paper examines communicating about complex challenges facing populations experiencing homelessness and examining alternative ways to communicate with these populations in times of crisis. Utilizing a case study approach, the researchers focused on cities in New York and California due to the high numbers of unhoused populations and individuals experiencing homelessness within these states. Experts in crisis and emergency management have provided invaluable recommendations on the general protection of life and property; however, individuals identifying as homeless or unhoused share characteristics that heighten their risk and vulnerability, such as lower socioeconomic status, unstable resilience levels prior to a crisis, and geographic disparities. The intersection of these attributes presents unique challenges for emergency managers and relevant public administrators when implementing crisis response and communication strategies, such as one-way written and oral messaging over media and social networks, along with enacting any new protocols needed in relation to the crisis itself, like targeted outreach. This paper discusses the evolution of crisis communication for homeless and unhoused populations, national statistics, along with analysis of case studies for Los Angeles, California, and New York City, New York. The paper concludes with eight major themes related to communicating with homeless and unhoused populations during times of crises and practical recommendations for emergency managers and relevant public administrators. It is critical that representatives and advocates for populations experiencing homelessness, or are unhoused, are involved in the dialogue and planning efforts. Stable investment in communication infrastructure and crisis communication programs and services is vital to assist homeless and unhoused populations in gaining access to the Internet and cell phone providers, outreach campaigns for printed messaging, alternative locations for media reporting, and receiving critical information during crisis and noncrisis periods. In terms of messaging, crisis-related alerts (oral and written) must be reviewed to ensure clarity in tone to avoid ambiguity and identify and remove any stigmatization language to open a two-way dialogue. Emergency managers and related public administrators must use a diverse array of communication avenues and strategies, such as social media and electronic messages (i.e., cell phones, media statements, and business signage) and traditional methods (i.e., leaflets at social service providers and shelters) with a focus on creating dialogue and empowering individuals to engage and seek out services. In addition, a crisis team dedicated to communicating with homeless and unhoused populations in times of crisis is needed along with dedicated resources for staffing, communication infrastructure, programs, and services. [ABSTRACT FROM AUTHOR]

This paper evaluated the congestion reduction benefits over a 6-year period from the implementation of an adaptive traffic control system (ATCS) in a congested area of Manhattan, New York, bounded by 2nd and 6th Avenues and 42nd and 57th Streets—known as the Midtown-in-Motion (MIM) area. A methodology using taxi Global Positioning System (GPS) sensors was used to measure traffic speed. Traffic speeds were calculated for May weekdays before the ATCS was installed (May 2011) and for each subsequent year (May 2012 to May 2016). Within 1 to 2 years after the implementation of the ATCS, the area’s traffic speed increased on avenues and cross streets. This gain, however, could not be sustained in subsequent years because of intervening changes in key factors impacting traffic congestion. These factors included reduction in roadway space/capacity for motor vehicles, lack of effective traffic enforcement to maintain/protect available roadway capacity, increased vehicle miles traveled (VMT) from transportation network company vehicles, and increasing volume of bicycle trips sharing street space with vehicles/pedestrians. This paper’s two key findings are, first, traffic speed gains initially seen in the MIM area after 1 year of ATCS implementation could not be sustained because intervening external factors reduced capacity and increased VMT. However, during the same analysis period, the rest of the Midtown Core area (without ATCS deployment) experienced a greater speed loss than the MIM area, indicating the effectiveness of ATCS deployment in minimizing losses in traffic speed. Second, to protect street network capacity and to minimize VMT growth, midtown Manhattan requires adopting proactive, collaborative, and coordinated strategies by the three key agencies involved with traffic management in New York City (NYC): the NYC Department of Transportation (traffic control system technology), the NYC Police Department (traffic enforcement), and the Mayor’s office (traffic demand mitigation policies). [ABSTRACT FROM AUTHOR]

Well-documented conditions of the country's subway systems suggest that the development of a management strategy for aging infrastructure is an important asset management challenge. The purpose of this work is to address this challenge by developing a statistical data analysis approach for forecasting the aging effect on the time-dependent deterioration rate of an identified trackway cluster. The infrastructure database is the New York City subway system and the trackway that supports the delivery of service. While much focus has been given to the steel rail subcomponent of the trackway, little has been done in the way of statistical analysis on the low-level nonconformances in the support structure of those rails—namely, the invert, ties, fasteners, and plates. Though detectable, these conditions pose no risk to either safety or the serviceability of that asset, yet they do provide a certain degree of awareness that an entirely intuitive lifecycle deterioration process is underway. This paper illustrates the development of a statistical data analysis methodology using available trackway data sets for forecasting the aging effect on the system performance. [ABSTRACT FROM AUTHOR]

Accurate forecasts of public transportation ridership are key components to a transit agency's management program. These forecasts are used to develop revenue projections that are then imputed into short-term and long-term maintenance, rehabilitation, and capital investment programming. The forecasts are complicated by the fact that many of the causes of the underlying variability, such as socioeconomic and land-use factors, are not constant over the network. Failure to account for these spatial processes will yield biased, inefficient, and inconsistent demand estimates. To overcome these challenges, the current paper presents a spatial Durbin model for analyzing the change in the New York City subway ridership between 2011 and 2016. The results indicate that subway stations experienced a greater increase in ridership over the study period when the stations served more train lines, were located in areas comprised of census tracts with a greater number of tax units (residential, commercial, etc.), or served lower mean household incomes. Furthermore, the subway stations located in areas surrounded by census tracts with more commercial property or higher median family income are also expected to have a greater increase in ridership. Lastly, ridership at a given station decreases due to an increase in ridership at neighboring stations. This may indicate that a change in ridership at a station is due, in part, to riders in a region changing which station they use instead of riders shifting from alternative modes of transportation. [ABSTRACT FROM AUTHOR]

COVID-19 had serious repercussions on public transportation throughout the USA. The aftermath of the peak of the crisis marked the path towards a slow and gradual recovery characterizing the shift to a new normal. Given the limited information on the recovery trends of public transportation, this paper compares the actual ridership and bus supply data for the years of 2019 and 2020 to study the timeline impacts of the pandemic on the bus system of the mid-sized city of Syracuse, NY. A data-driven analysis is presented across the city's bus routes, university bus routes, and categorical bus stops. Various census tract socio-demographic data are also correlated with passenger activity changes and mapped using ArcGIS. The findings show that overall bus ridership in 2020 fell by 70%, on average, during the three months that followed the onset of the pandemic. Since the lifting of the initial restrictions, concerns about using public transportation had partially been alleviated; however, passengers remained reluctant with ridership decline stabilizing at approximately 55% during the last four months of the year. While bus lines serving the university area, which houses a high percentage of youth, were severely affected by the pandemic, passenger activity near hospital stops were less affected and those near major supermarkets/ hypermarkets seemed unaffected, showing a surge especially in the two months that followed the onset of the pandemic. Passenger activity at census tracts having low poverty levels mostly located on the outskirts of the city of Syracuse were the least affected tracts in the last six months of 2020. It is anticipated that the insights presented will help service planners in preparing for similar future events by better understanding what stops and routes are deemed essential during a public health crisis and how the socio-demographics impacted the recovery after restrictions were removed. [ABSTRACT FROM AUTHOR]

Since the enactment of the first New York City (NYC) facade inspection ordinance in 1980, eight five-year complete cycles have been registered. The paper is a commentary on the 40-year years' evolution of the practice of facade inspection and repair as influenced by technical developments, changes in legislation and building owners' attitudes. The large number of number of buildings (by now 16,000) and the number of cycles made NYC the principal terrain where methods of inspection and repair techniques were tested. The interpretation of the law was refined by rules issued in response to recurring failures. In 1980, there were few professionals knowledgeable of the causes of facade distress and effective repair methods. Gradually, the various types of facade distress found explanations and adequate repair solutions were developed; a professional specialty dedicated to facade conditions has reached maturity. The author supports the arguments with various descriptive statistics of inspection ratings, violations, applications to repair, all corelated with the NYC typologies. A quantitative proof of success could not be deduced from an analysis of inspection ratings of four successive cycles, as the rating definitions have evolved over the last 20 years. A reduction in number of decaying facades is noticeable, but accidents have continued to occur. The public awareness and concerns about the risks posed by facades has increased and as expectations remain high, the scope of the Facade Inspection and Safety Program (FISP) has evolved from minimizing the number of accidents to a timely protection from hazards. [ABSTRACT FROM AUTHOR]

Undeniably, climate-change-induced sea-level rise has served as a powerful driving force for the occurrence of coastal storms more severe than ever before. Low-lying metropolitan coastal areas, in particular, have become increasingly vulnerable to coastal flooding as a result of the rapid expansion of urbanization along flood-prone areas. Safeguarding coastal communities from the repercussions of flooding through the utilization of best management practices (BMPs) is one of the most effective ways of alleviating the situation. However, solely relying on inshore BMPs might not be the best possible approach when the storm event's intensity can be reduced before the storm reaches the shoreline through the installment of offshore BMPs. Moreover, many recent studies have confirmed the cost-effectiveness and usefulness of natural elements, especially when combined with engineering solutions. This paper assesses the overall suitability and effectiveness of various combinations of nature-based inshore and offshore BMPs for coastal flood mitigation of storms with different intensities with applications to the Southern Brooklyn area in New York City. Moreover, inevitable conditions stemming from climate variability and change have made the assumption of stationary recurrence of extreme events unreliable. Furthermore, historical events of remarkable impacts have not been considered differently in the attainment of the flood design values. Thus, as one of the main objectives of this study, and in order to consider both, a nonstationary partial frequency analysis is utilized, including the major historical storms jointly with the precipitation data in the study area to obtain 100-year flood design values. To achieve the goals of the study, first, the offshore simulation was carried out using the Delft3D hydrodynamic model, developed by Deltares, in order to find the water level hydrograph for the ungauged areas of interest, with and without offshore BMPs followed by the simulation of the flood events on the inland coastal area using gridded surface subsurface hydrologic analysis (GSSHA), a module of the watershed modeling system (WMS) developed by the USACE, to assess the effectiveness of inshore BMPs. The proposed scenarios are tested against Superstorm Sandy, Hurricane Irene, and the 100-year flood hydrographs. The results showed a remarkable coastal flood wave height and water level reduction when integrating offshore and inshore green BMPs. [ABSTRACT FROM AUTHOR]

The devastating impacts of frequent coastal storms, such as Hurricane Katrina in New Orleans in 2005 or Superstorm Sandy in New York City in 2012, in major low-lying metropolitan areas have had repercussions far beyond previously experienced disasters. Two key findings that describe these repercussions related to these events were stated as follows: in the case of Katrina, there was a lack of holistic or system-based thinking, and in the case of Sandy, there was an insufficient integration of critical infrastructure. Among different remediation actions, inland placement of best management practices (BMPs) in order to protect coastal cities from storm surges has received a lot of attention. However, nearshore BMPs as a way of source (wave height) reduction have not yet been thoroughly investigated. Nearshore practices are especially attractive in coastal areas that experience significant wave heights as a total water level component. In this paper, the effects of bathymetric shallowing through an apron on reducing the wave height and water level during storms are investigated in coastal areas. Southern Brooklyn in New York City is selected as the case study. A hydrodynamic model is utilized to generate wave height and storm tide. A water-level hydrograph in ungauged areas of the case study is constructed, which has not been realized before in similar coastal flood studies. Water level variations are investigated to include generated storm surge and wave characteristics. The results show that shallowing can reduce the peak of wave height and water level by 47% and 10%, respectively, in open coastal areas. In a more contained bay area, the reduction of a water level was more than 13%. These figures show the potential of nearshore BMP applications that could significantly improve our flood preparedness plans. The proposed methodology can be applied to other coastal geographical settings. [ABSTRACT FROM AUTHOR]

The article presents a paper on the concept of accidental demolition, whereby a heavy damage sustained by a level of a building results to the eventual collapse of the upper part to the lower one in a sequence that crushes other levels in the process. It focuses on the treatment of equations of motion where few numbers are quoted relating to physical properties of the World Trade Center (WTC) towers. Comments are included to fill that gap and also to determine the applicability of this concept.

This work supported the Federal Highway Administration (FHWA) in presenting state and metropolitan area vehicle occupancy information in compliance with Title 23 of the US Code of Federal Regulations, Part 490 National Performance Measures. The basic goal is to provide and introduce a statistically effective and realistic approach to approximate bus occupancy rates for each US state and Washington, DC. Bus occupancies were calculated separately for transit buses, school buses, and motorcoaches. The average total bus occupancy was determined by aggregating the average occupancy of the vehicle for the three groups weighted by annual vehicle miles traveled. Regarding transit buses, the National Transit Database (NTD) of the Federal Transit Administration (FTA) was used to measure the occupancy of transit buses. For school buses, state transportation statistics from 2015-2016 were used to measure average school bus occupancy for each state. Data provided by the Port Authority of New York and New Jersey (PANYNJ) for the Port Authority Bus Terminal (PABT) in New York City, the largest US bus terminal, were used to measure the occupancy rates for motorcoaches. Results on state-level bus occupancy rates are summarized. The paper concludes with guidelines for future data collection, validation, and training. The date, code, and user guide of this study can be found at an online GitHub repository. [ABSTRACT FROM AUTHOR]

This paper describes the important engineering features relating to the design and construction of a deep excavation for power canal, intake, and powerhouse structure of the Hudson Falls hydroelectric development on the Hudson River at Glens Falls, N.Y. The excavation is located in a medium hard shale with shallow dipping bedding, numerous intersecting joint sets, and several varieties of fractures. This paper presents the engineering evaluation of the slopes and identifies the importance of flexibility of construction contracts and division of responsibility between engineer and contractor to achieve a high level of cooperation in producing a very successful project. [ABSTRACT FROM AUTHOR]

This paper presents a detailed investigation on numerical simulation of an accidental fire on the Ed Koch Queensboro Bridge, which is a major long-span truss bridge connecting Manhattan to Queens in New York City. A truck traveling on the lower deck of the bridge caught fire, which spread to major bridge components supporting the upper deck. The fire was observed to last approximately 30 min. The heat released from the fire severely damaged two exterior stringers of the upper deck supporting an exterior lane, which led to the closure of this lane for several weeks. This paper presents detailed research on numerical simulation of the entire process of the fire and prediction of the structural response of the deck subjected to the fire loading. The simulation results show very good correlation between the simulated and observed damages, where the simulated out-of-plane deformation of the exposed stringers agrees well with measured deformations. The methodology presented in this paper is an effective approach for fire-structure interaction modeling and simulation and has the potential for application to other civil structures. [ABSTRACT FROM AUTHOR]

A bridge across the Hudson River opposite Manhattan Island was a dream that started in the early 19th century. Many giants of civil engineering, including Gustav Lindenthal and Othmar Ammann, were involved in planning such a bridge but it was not until 1931 that Ammann’s George Washington Bridge crossed the river. This paper covers the period from 1805 to 1935. [ABSTRACT FROM AUTHOR]

The objective of this study is to measure the effectiveness of three commonly used changeable message sign (CMS) messages in reducing vehicular speeds and variances in highway work zones. This paper presents the results of a field study conducted on Interstate-90 in western New York State to evaluate the use of three different types of messages displayed on a CMS, as a speed control measure. The study included speed measurements of nearly 180,000 vehicles. The three types of CMS messages tested were: (1) RIGHT|LANE|CLOSED∼KEEP|LEFT; (2) WORK ZONE|MAX SPEED|45 MPH∼BE|PREPARED|TO STOP; and (3) LEFT|LANE|CLOSED∼KEEP|RIGHT. Of the three CMS messages tested, the CMS message stating “WORK ZONE|MAX SPEED|45 MPH∼BE|PREPARED|TO STOP” proved the most effective, significantly reducing vehicle speeds by 3.3–6.7 mi/h(5.3–10.8 km/h). The other two CMS messages were not as effective. The standard deviation of speed for the CMS message: WORK ZONE|MAX SPEED|45 MPH∼BE|PREPARED|TO STOP increased by 1.1–1.7 mi/h(1.8–2.7 km/h) in the driving lane and 0.2–2.0 mi/h(0.3–3.2 km/h) in the passing lane. The speed variances for the other two CMS messages ranged from -2.00 to 1.13 mi/h (from -3.23 km/h to 1.83 km/h). [ABSTRACT FROM AUTHOR]

Following the collapse of the World Trade Center towers in September 2001, there has been heightened interest among building owners and government entities in evaluating the progressive collapse potential of existing buildings and in designing new buildings to resist this type of collapse. The General Services Administration and Department of Defense have issued general guidelines for evaluating a building’s progressive collapse potential. However, little detailed information is available to enable engineers to confidently perform a systematic progressive collapse analysis satisfying these guidelines. In this paper, we present four successively more sophisticated analysis procedures for evaluating the progressive collapse hazard: linear-elastic static; nonlinear static; linear-elastic dynamic; and nonlinear dynamic. We discuss the advantages and disadvantages of each method. We conclude that the most effective analysis procedure for progressive collapse evaluation incorporates the advantageous parts of all four procedures by systematically applying increasingly comprehensive analysis procedures to confirm that the possibility of progressive collapse is high. [ABSTRACT FROM AUTHOR]

With the rapidly changing landscape for taxis, ride-hailing, and ride-sourcing services, public agencies have an urgent need to understand how such new services impact social welfare: impacts of technologies on matching customers to service providers, evaluating ride-sourcing operations, and evaluating surge pricing policy, among others. We conduct an empirical study to answer this question for Uber using a dynamic spatial equilibrium taxi-matching model. Given a matching function, the spatial distribution of demand activities, and service coverage, the model outputs equilibrium fleet sizes, matches, and social welfare by zone and time of day. Uber provides pickup data for a specific time period in New York City (NYC). Parameters from the model calibrated from medallion cab (Taxi) data are grafted onto the Uber model to supplement the missing information. The Uber model has a root-mean square error of 7.75 matches/zone/interval, which is approximately an 8.52% error. Spatial distribution of responses in demand to fare hikes or vehicle supply to demand surges measurably differ between NYC Taxi and Uber markets. Baseline estimations of welfare indicate that the NYC Taxi industry generates $495,900 in consumer surplus and $1,022,400 in Taxi profits for the 4-h interval, while for the Uber market, the model estimates $73,300 in consumer surplus and $151,300 in Uber profits during the same interval. Spatial-temporal dynamics resulting from fare hike and congestion fee scenarios are analyzed to determine requirements for allocating the congestion charge revenues toward public transit to maintain or improve upon the same consumer surplus. [ABSTRACT FROM AUTHOR]

This paper describes the MSRP (Model for Station Rehabilitation Planning) for selecting subway stations for rehabilitation. This method evaluates the stations at four different levels: (1) technical/social evaluation including functional criteria and social/community/political criteria; (2) database, which includes cost estimates for partial and full rehabilitation of stations with respect to functional and social/political criteria; (3) funding sources and constraints; and (4) management constraints. The existing procedure for station selection for rehabilitation used by the Metropolitan Transit Authority New York City Transit (MTA NYCT), various criteria used for evaluation, and limitations of the system are described. The development of the MSRP has been explained in relation to the MTA NYCT system requirements, and the procedure of the MSRP has been explained through a hypothetical example. This paper illustrates the results and the benefits of the proposed model for station rehabilitation planning. [ABSTRACT FROM AUTHOR]

The article presents a discussion on the paper "Simple Estimation of Prevalence of Hortonian Flow in New York City Watersheds" by M. Todd Walter, Vishal K. Mehta, Alexis M. Marrone, Jan Boll, Pierre Gerard-Marchant, Tammo S. Steenhuis, and Michael F. Walter. The paper is a welcome contribution to the engineering literature, as it raises the issue of the process and pathway of delivery of water to stream. The paper examines critically the prevalence of Hortonian flow in the New York City watershed. The authors find Hortonian overland flow occurrence to be highly restrictive in terms of rain intensities and durations.

Series of measurements of the motion of the Verrazano-Narrows Bridge during the November 7, 2004, New York City Marathon were made to evaluate the level of vibrations during the race. This paper presents details of the testing protocols and recorded data analyses as related to the bridge and the runners' level of vibration perception. From the analysis of the recorded data, the excited local mode of the bridge deck within the range of the runners' step frequency was identified. In addition, the computed bridge global response using observed runner density and estimated weight showed excellent agreement with the bridge measured response. It was also found that based on the analyses of the recorded data, the bridge deck vibration level during the marathon was within the acceptable range for the runners. [ABSTRACT FROM AUTHOR]

This paper describes the New York City water supply performance and suppression of fire during the World Trade Center (WTC) disaster. The water losses sustained by damaged water distribution pipelines are discussed and their impacts on emergency response and telecommunications and transportation infrastructure are noted. The results of hydraulic network analyses are presented to quantify the performance of hose and engine relay systems from fireboats to the WTC site. The results of an analytical study of firefighting relay systems are summarized to provide guidance on the most effective selection of hose size, number of hose lines, and engines for future use of fireboats for landside fire protection. The fire department response to the WTC disaster is compared with similar response to the 1989 Loma Prieta earthquake. Drawing on lessons from both events, recommendations are made for improved emergency planning and services. [ABSTRACT FROM AUTHOR]

Offshore wave setup generated by wave breaking during coastal storms can create significant flow through tidal inlets and increase bay flooding. However, these flow contributions are not always considered when determining coastal flooding risk for engineering studies. This paper describes the wave-driven flow process at tidal inlets and demonstrates its impact on bay flooding on Long Island, New York. Numerical simulations using a coupled hydrodynamic and wave model are presented to show contributions to bay water level by wave-driven flow with respect to those by wind surge. These simulations include two major historical coastal storms and a small nor’easter in 2003, during which the model was validated using field measurements of water level. Finally, an approach is introduced for estimating wave-induced flow contributions to bay flooding as a function of inlet and storm characteristics, including tidal prism and wave conditions. The findings of this study indicate that wave-induced flow contributions make up 15–35% of the total storm surge, where the wave-induced flow contribution increases with increased inlet efficiency. [ABSTRACT FROM AUTHOR]

The Manhattan Bridge is one of the first examples of an urban bridge whose design was impacted by partisan politics and a desire for a more, in the eyes of some, esthetically pleasing suspension bridge. It was the third bridge to be built across the East River and its design resulted in a battle between Leffert L. Buck, his associates R. S. Buck, and O. F. Nichols and Gustav Lindenthal, the Commissioner of Bridges in New York City, appointed after the preliminary design of the bridge had been completed. This paper is about that battle. [ABSTRACT FROM AUTHOR]

Foundation construction adjacent to landmark structures can present numerous challenges for the geotechnical engineer and contractor, including difficult geology, unexpected subsurface conditions, limited access, and massive and relatively heavily loaded foundation elements, in addition to being sensitive to their historic fabric. This paper presents two case histories where underpinning was successfully executed in two different geologic settings and utilized various techniques. [ABSTRACT FROM AUTHOR]

This paper presents some findings of the FEMA and SEI/ASCE sponsored studies of structural performance of New York’s World Trade Center (WTC) following the attacks of September 11, 2001, and the Murrah Building following the April 19, 1995, Oklahoma City bombing. The WTC collapses were caused not by aircraft impact alone but by the combination of impact and the resulting fire that weakened structural members and connections. On the other hand, the Murrah Building collapsed as a direct result of the blast. Although these studies call for further research in a number of areas, this report summarizes some of the lessons learned. [ABSTRACT FROM AUTHOR]

The impacts of COVID-19 on for-hire vehicle (FHV) (e.g., Uber/Lyft, often referred to as transportation network companies in other locations) and taxi use have been relatively understudied compared with transit and personal vehicles. This study analyzed and estimated the changes in ridership for taxis and FHVs in New York City during the COVID-19 pandemic to determine whether it had disproportional impacts on these competing modes, how these impacts varied over time and space, and the associated factors. Data supporting the analyses came from the Taxi and Limousine Commission, the COVID-19 Data Repository, Google's Community Mobility Reports, the American Community Survey, and the Primary Land Use Tax Lot Output. Temporal change was measured by the daily taxi/FHV ridership deviation from a defined baseline, which showed that COVID-19 more negatively impacted taxis than FHVs. Temporal moving average models were then employed, which showed that COVID-19 had different temporal impacts on taxis and FHVs in relation to the parameters' significance, magnitude, and temporal correlation patterns. In general, taxi/FHV ridership dropped when people spent more time at home and the number of confirmed COVID-19 cases was greater. The spatial variation in taxi/FHV ridership was measured by the coefficient of variation. Spatial regression models indicated that the land use of a zone affected taxi/FHV ridership during the pandemic. In addition, a zone with more carless/car-free households, older persons, or more children enrolled in school was more likely to experience a decrease in taxi/FHV ridership. A zone with more workers who commuted by walking or taking transit (excluding taxis) in pre-COVID times was more likely to see a decrease in taxi/FHV ridership. A zone with more people working from home pre-COVID, was more likely to see an increase in FHV ridership. The models showed that COVID-19 had greater spatial impacts on taxis than FHVs. Based on these results, this study provides insights as to what factors affected ridership of the two competing travel modes and suggests actions that transportation authorities could take to reduce temporal and spatial impact disparities. [ABSTRACT FROM AUTHOR]

The article presents an introduction to articles published within the issue is presented, including one on a presentation delivered as part of the Brooklyn Bridge 125th anniversary celebration in 2008, and also the provides the list of 2008 Outstanding Paper Award honored by the American Society of Civil Engineers.

Significant research has been conducted on the practice of bridge asset management (BAM). Although bridge site inspections yield observations on current conditions, their usefulness in a bridge asset management strategy requires a sound historical and statistical basis. Therefore, the present practice of bridge site inspection can only support a reactive mode in bridge asset life cycle management and is raising a critical need for a risk analysis methodology that will effectively support decision making in a forecasting mode. This research addressed that challenge by employing a series of relatively simple, well-established statistical techniques as a precursor to a forecasting methodology. A knowledge-based risk assessment method (RAM) is recommended for optimizing BAM of the New York City Department of Transportation (NYCDOT) bridge database. The limitations of the current practice of bridge condition rating are reactive in nature. Reactive approaches do not provide analytical tools for forecasting the aging effect on the time-dependent bridge infrastructure deterioration for the prioritization of BAM. The development of statistical data analysis can be done by using the aging effect on the corrosion rate as a health monitoring parameter of the girder. The results of this research provide bridge asset managers with a statistical data-driven analysis approach to the time-dependent aging effect as a decision support tool for preemptive prioritization and a prespecified vulnerability level in BAM planning. The infrastructure base selected for this study was 92 steel girder bridges with concrete decks (single-span/multispan) managed by NYCDOT, which were clustered into eight major age groups. There were multiple primary member degradation indicators, e.g., corrosion, section loss, cracks, and others. This research analyzed the corrosion rate of primary members. It illustrated the application of statistical data analysis for the development and application of RAM for forecasting the effect of aging on the corrosion rate as a structural degradation indicator for the preemptive planning of a BAM strategy. [ABSTRACT FROM AUTHOR]

The article discusses the subject article "What Did and Did Not Cause Collapse of World Trade Center Twin Towers in New York?." It contends that the simple math plus observations of the World Trade Center (WTC) twin towers videos prove that the model of the article's authors are wrong. It notes that describing the destruction of WTC1 uses differential equations is not necessary. It points out that the upper most story of part A developed a layer of debris during the first tower's crush.

The article presents insight on the closure of the article "What Did and Did Not Cause Collapse of World Trade Center Twin Towers in New York?." It notes that the discusser's claim that the theory of its authors is wrong has no basis. It points out that his claims on the insignificance of differential equations as to the collapse model of the World Trade Center (WTC) is incorrect. It also finds its claims that the model does not consider energy for rubble compression ridiculous.

The article focuses on the article published in the July 2002, issue of the "Journal of Engineering Mechanics," on various preventive measures that could have prevented the collapse of World Trade Center. According to the author, when a lateral load hits the intermediate stories of a tall building, the vertical load transmission path gets disrupted. Consequently, the intermediate stories hang on to the undamaged top portion of the building and exert an enormous pull with their massive self-weight. Because of this phenomenon, the WTC towers had a collapse failure and this was aided by the conflagration of the aircraft fuel spilled inside the building. The conflagration due to aircraft fuel in the WTC towers apparently heated the building to a temperature of over 800°C. Obviously, the various energy-absorbing materials considered cannot withstand such a sustained temperature. The author explains the possible constructional features to prevent the collapse of tall buildings like WTC. The article also presents an acknowledgement of thanks from writers of the discussion to the article's writer to clarify their papers.

Discusses the approach to the cable strength problem for the Williamsburg Bridge in New York City.

The article focuses on the article published in the July 2002, issue of the "Journal of Engineering Mechanics," on various preventive measures that could have prevented the collapse of World Trade Center. According to the author, when a lateral load hits the intermediate stories of a tall building, the vertical load transmission path gets disrupted. Consequently, the intermediate stories hang on to the undamaged top portion of the building and exert an enormous pull with their massive self-weight. Because of this phenomenon, the WTC towers had a collapse failure and this was aided by the conflagration of the aircraft fuel spilled inside the building. The conflagration due to aircraft fuel in the WTC towers apparently heated the building to a temperature of over 800°C. Obviously, the various energy-absorbing materials considered cannot withstand such a sustained temperature. The author explains the possible constructional features to prevent the collapse of tall buildings like WTC. The article also presents an acknowledgement of thanks from writers of the discussion to the article's writer to clarify their papers.

The delivery of large quantities of turbidity-causing particles over relatively brief intervals of high stream flow and the complexity of the resulting turbidity () patterns imparted to receiving lakes and reservoirs requires the use of innovative technologies to fully resolve both the driving signals and the resulting signatures in the receiving waters. The design and implementation of a robotic monitoring network to address the problem of high events in reservoirs of New York City's multireservoir unfiltered water supply are described. The evolution of the role of these technologies in supporting management of the system related to the issue is described, including (1) resolution of cause and effect relationships between tributary inputs and in-reservoir patterns; (2) insights into mediating processes; and (3) critical support for the development, testing, and application of mechanistic mathematical models. The contemporary robotic monitoring network of eleven tributary and reservoir deployments continues to support management deliberations of alternatives to minimize the effect of major runoff events as they occur. These data streams are being integrated into a forthcoming near-real-time decision support tool that will provide automated guidance in the context of multiple factors and objectives for this complex water supply. [ABSTRACT FROM AUTHOR]

This study investigates vibration characteristics of a truss bridge that has been retrofitted with a fiber reinforced polymer (FRP) deck. The bridge is located on State Route 367 in Wellsburg, Chemung County, New York. It is a 140-ft-long (approximately 42.7-m-long) truss structure, originally built with a noncomposite concrete deck. The concrete deck was replaced with a much lighter fiber reinforced polymer deck to improve the bridge load capacity ratings. This study investigates the vibration characteristics of the bridge as a result of the deck replacement and impact of these changes on the structural behavior. The results indicate that the fundamental frequency for the current structure with the FRP deck is approximately 45% higher than that for the original structure with a concrete deck. The computed bridge fundamental frequency correlated well with field data. When compared to the concrete deck bridge, the FRP deck bridge resulted in lower dead load forces, higher live load forces, lower total forces, and higher live load stress ranges used in fatigue life estimates. Dynamic allowance was also determined for each of the selected members for both concrete and FRP decks. For the concrete deck bridge, the calculated dynamic allowance is higher than those used in bridge design specifications. Lower dynamic allowances were obtained for the FRP deck bridge. [ABSTRACT FROM AUTHOR]

The article features New York structural engineer Homer Gage "H. G." Balcom and his creation for Empire State Building in New York. It states that Balcom studies civil engineering at the Cornell University and worked with several companies including Berlin Iron Bridge Co., American Bridge Co. (ABC), and American International Shipbuilding Corp. (AISC). It says that the creation for the Empire State Building required costs of 24.7 million dollars and construction period of 13 months.

A significant portion of nonrecurrent freeway congestion is caused by incidents. This nonrecurrent congestion negatively impacts safety and mobility. It produces enormous travel delay and results in secondary incidents, which cause additional delay and injury. The simulation-based secondary incident filtering (SBSIF) method is proposed for identifying secondary incidents from archived incident data. The proposed methodology is computationally efficient and overcomes deficiencies of existing techniques. It is evaluated on incident data from a 6-month period along a segment of I-287 in the New York state. Results of the evaluation show that the SBSIF method has a significantly reduced misclassification rate (e.g., a reduction of 58 percentage points and greater) as compared with static methods commonly used in practice, despite that, it requires comparable computational effort. [ABSTRACT FROM AUTHOR]

Construction projects, private and public alike, have a long history of cost escalation. Transportation projects, which typically have long lead times between planning and construction, are historically underestimated, as shown through a review of the cost growth experienced with the Holland Tunnel. Approximately 50% of the active large transportation projects in the United States have overrun their initial budgets. A large number of studies and research projects have identified individual factors that lead to increased project cost. Although the factors identified can influence privately funded projects the effects are particularly detrimental to publicly funded projects. The public funds available for a pool of projects are limited and there is a backlog of critical infrastructure needs. Therefore, if any project exceeds its budget other projects are dropped from the program or the scope is reduced to provide the funds necessary to cover the cost growth. Such actions exacerbate the deterioration of a state’s transportation infrastructure. This study is an anthology and categorization of individual cost increase factors that were identified through an in-depth literature review. This categorization of 18 primary factors which impact the cost of all types of construction projects was verified by interviews with over 20 state highway agencies. These factors represent documented causes behind cost escalation problems. Engineers who address these escalation factors when assessing future project cost and who seek to mitigate the influence of these factors can improve the accuracy of their cost estimates and program budgets. [ABSTRACT FROM AUTHOR]

A three-dimensional hydrodynamic model, MIKE 3, was used to assess the effects of the cooling water thermal plume from the 877 MW Charles Poletti power plant that discharges to the East River in Queens, New York City. The East River is a tidal strait that connects New York Harbor and Long Island Sound—two large, out of phase estuaries with complex hydrodynamics. The study was additionally required to account for the thermal discharge of a larger, 1253 MW power plant adjacent to Poletti. The model used a flexible mesh formulation based on unstructured triangular elements and was successfully calibrated with triaxial thermal field survey data. After calibration, the model was used to demonstrate that under worst case conditions the resulting thermal plume did not exceed the regulatory thermal criteria. [ABSTRACT FROM AUTHOR]

Previous analysis of progressive collapse showed that gravity alone suffices to explain the overall collapse of the World Trade Center Towers. However, it remains to be determined whether the recent allegations of controlled demolition have any scientific merit. The present analysis proves that they do not. The video record available for the first few seconds of collapse is shown to agree with the motion history calculated from the differential equation of progressive collapse but, despite uncertain values of some parameters, it is totally out of range of the free fall hypothesis, on which these allegations rest. It is shown that the observed size range (0.01–0.1 mm) of the dust particles of pulverized concrete is consistent with the theory of comminution caused by impact, and that less than 10% of the total gravitational energy, converted to kinetic energy, sufficed to produce this dust (whereas, more than 150 t of TNT per tower would have to be installed, into many small holes drilled into concrete, to produce the same pulverization). The air ejected from the building by gravitational collapse must have attained, near the ground, the speed of almost 500 miles per hour (or 223 m/s, or 803 km/h) on average, and fluctuations must have reached the speed of sound. This explains the loud booms and wide spreading of pulverized concrete and other fragments, and shows that the lower margin of the dust cloud could not have coincided with the crushing front. The resisting upward forces due to pulverization and to ejection of air, dust, and solid fragments, neglected in previous studies, are indeed found to be negligible during the first few seconds of collapse but not insignificant near the end of crush-down. The calculated crush-down duration is found to match a logical interpretation of seismic record, while the free fall duration grossly disagrees with this record. [ABSTRACT FROM AUTHOR]

The collapse behavior of the World Trade Center towers is considered formally as a propagating instability phenomenon. The application of associated concepts enables the residual capacities of both towers after the onset of collapse to be formally estimated. This information is combined into a simplified variable-mass collapse model of the overall dynamical behavior. The resulting, nonlinear governing equation of motion can be solved in closed form, to yield compact information about the overall collapse conditions. [ABSTRACT FROM AUTHOR]

Images of structural collapse crowd our globalized television screens; from wars, terrorist bombs, and earthquakes. The outcomes often look quite similar, but what are the engineering differences? Look first for differences relating to collapse mechanisms: (1) earthquake engineering focuses on sway collapse mechanisms in which the building as a whole moves sideways and may collapse under its own weight; and (2) explosions may remove one or several load-bearing columns, walls or transfer structures leading to vertical collapse and the “double-span mechanisms” of GSA (2003). Records of earthquake damage show that earthquakes can also remove supports, often corner columns causing two-way cantilever mechanisms. Earthquake engineering does need to include recognition of “lost column” events and to incorporate design against progressive collapse. Common to earthquakes and to explosions is the need for ductile detailing and ductile detailing for lost column events is similar to that for earthquakes if not always for the same reasons. Ductility does need to relate to specific collapse mechanisms and so, although earthquake engineering is an excellent starting point for design against progressive collapse, it does need to adapt so as to include the “double span” mechanisms at lost supports. [ABSTRACT FROM AUTHOR]

This study investigates impacts of the 2001 World Trade Center attack on critical infrastructure systems in the New York City metropolitan area. Of particular interest are the physical or logical connections—also known as interdependencies—among these systems, and the impacts of the attack on them. This study extends knowledge about the behavior of complex and interdependent infrastructures systems following a significant disruption. The results depict impact to all infrastructure systems as a result of the attack, with disruptions reported throughout the 3 month study period. Approximately 20% of these disruptions involved interdependencies, and a majority of infrastructure systems were involved in at least one interdependency. The results therefore suggest that interdependence is a pervasive condition of New York City’s critical infrastructures. Accordingly, approaches to planning for and managing infrastructure-related disruptions, particularly those involving interdependency, are discussed. [ABSTRACT FROM AUTHOR]

The construction of the Battery-Joralemon Street Tunnel is described. Built between 1903 and 1907, it was the first subway tunnel placed in service under the East River between Manhattan and Brooklyn. Both heading-and-bench rock tunneling and pressurized shield soft-soil tunneling techniques were used. Loss of control of the tunneling shield in partially saturated sands caused variations in alignment that made portions of the tunnel nonfunctional. Approximately 3,000 ft of the tunnel had to be reconstructed to enable subway cars to use the tunnel safely. Additionally, due to concerns regarding the stability of the tunnel in the soft soils, piles were installed under the tunnel to bedrock. The project was a crucible for subway contractors and engineers of the Rapid Transit Commission, especially Clifford M. Holland. His experience on the Joralemon Street Tunnel enabled him to efficiently and safely complete four other East River subway tunnels after the Dual System Agreement of March 1913. [ABSTRACT FROM AUTHOR]

At the September 11, 2001, terrorist attacks on the New York World Trade Center (WTC) Towers, extensive structural damage, including localized collapse, occurred at several floor levels directly impacted by the aircraft. Despite this massive localized damage, each structure remained standing for approximately 1 h or 1 h 30 min. Although the damage to the beams and columns in the perimeter tube of each tower were clarified in the published ASCE/FEMA report, the damage to the floor system and inner core columns were not estimated. The purpose of this study is to determine why the towers remained standing after impact through several analytical studies, including impact analyses using a simplified model to estimate the overall damage, a rigorous finite element model to estimate the local damage, and stress analyses after some structural members are lost. The results of the stress analyses show why both buildings did not collapse immediately after impact, and WTC2 collapsed sooner than WTC1. [ABSTRACT FROM AUTHOR]

The diffusive release of polychlorinated biphenyls (PCBs) from sediments to water under low-flow conditions was measured for surficial sediments with different PCB concentrations collected from the Grasse River near Massena, N.Y. Data on PCB sediment-water equilibrium partitioning and PCB mass release flux from sediments were used to assess the extent and mass transfer rate of PCB release under low-flow conditions in the Grasse River. Microcosm studies were employed to evaluate the release flux of PCBs under quiescent conditions for various river sediments and sediment mixtures. The observed total-PCB release fluxes ranged from about 1 to 20 mg/m2·year, showing predominantly dichloro- through tetrachlorobiphenyls. Analyses of water column samples from the Grasse River under low-flow conditions also indicated the predominance of dichloro- through tetrachlorobiphenyls as in the microcosm tests. Data on PCB equilibrium partitioning between water and sediment were used to estimate sediment porewater concentrations, and these data combined with the microcosm flux data were used to estimate average, aqueous-boundary-layer total-PCB mass transfer coefficients of 0.3–1.5 cm/day. These values are consistent with estimates of mass transfer coefficients based on aqueous-boundary-layer correlations, and with PCB mass transfer coefficients inferred from the field data for low-flow conditions in the fall and winter (approximately 2 cm/day). The correspondence of the laboratory results with the field measurements and mass transfer rates demonstrates the usefulness of the microcosm technique for estimating fluxes of PCBs from river sediments under low-flow minimum bioturbation conditions. [ABSTRACT FROM AUTHOR]

Final design of the replacement orthotropic deck panels for the rehabilitation of the Williamsburg Bridge in New York City was based on laboratory fatigue tests of a full-scale prototype and an as-built orthotropic deck panel carried out at Lehigh University in the latter 1990s. The tests focused on determining and comparing the fatigue resistance of two different welded rib-to-diaphragm connection details that were recommended in the 1994 AASHTO LRFD Bridge Design Specifications and an alternative proposed by Steinman. The test on the prototype panel demonstrated that the fatigue resistance of the alternative detail was superior and influenced additional design changes that were incorporated into the replacement panels installed on the southern inner and outer roadways. Subsequent tests on the as-built panel further confirmed that the fatigue resistance of the alternative detail was superior and demonstrated that the additional design changes were also beneficial. Static and dynamic tests revealed the complex behavior of the orthotropic deck panels and demonstrated the effectiveness of retrofit and repair options at cracked connections. An assessment of fatigue resistance based on fracture mechanics models provided theoretical correlation. This research has led to the revision of design specifications for steel orthotropic decks first provided in the 2000 Interim AASHTO LRFD Specifications. [ABSTRACT FROM AUTHOR]

This study was a statistical evaluation of the prevalence of infiltration excess runoff (i.e., Hortonian flow) for undeveloped areas within New York City (NYC) watersheds. Identifying the hydrological processes generating runoff is central to developing watershed management strategies for protecting water quality. Fifteen-minute rainfall data from East Sidney, N.Y. (1971-2002) were used as maximum observed intensities. Maximum exceedance analyses were performed on a monthly basis to investigate seasonal rainfall intensity trends. Hortonian flow was assumed to occur whenever the rainfall intensity exceeded the soil permeability. Soil permeabilities were obtained from the U.S. Natural Resource Conservation Service soil survey. Results show that Hortonian flow is unlikely to occur anywhere for events smaller than the 3-year 15-min event. Only for the summer months, May-August, is Hortonian flow expected for 15-min intensities of <10-year magnitude. However, the summer results are overpredicted by this analysis because these months typically have the driest soil conditions and thus the highest infiltration capacity. This analysis concludes that infiltration excess runoff is not a dominant runoff process in undeveloped portions of NYC watersheds. [ABSTRACT FROM AUTHOR]

The September 11, 2001, terrorist attacks on the World Trade Center and the Pentagon presented unique teachable moments to engineering educators but with the competing demand to complete the course as designed and as dictated by the tyranny of the syllabus. A questionnaire was administered to undergraduate students enrolled in three professional ethics courses in 2001 and 2002 to ascertain the extent to which their instructors used the events as teachable moments. For comparison, the questionnaire was administered 1 year after the attacks to students enrolled in courses of an academic enrichment program at Duke University and environmental science students at North Carolina Central University. The percentage of courses addressing the events was highest in the Fall 2001 semester, when the attacks occurred, falling in the Spring 2002 semester, but increasing in Fall 2002. Most respondents supported the use of the events as teachable moments even if the syllabus and course outline had to be adjusted. The results indicate that engineering education must be open to opportunities to teach physical science and engineering concepts and to introduce the students to the social sciences and humanities. [ABSTRACT FROM AUTHOR]

The feasibility of protecting tall buildings against progressive downwards collapse following catastrophic structural failure at high level is explored and various design suggestions made. [ABSTRACT FROM AUTHOR]