Civil and Environmental Engineering Commons^™

Can Generative Ai Make Farming Decisions? Current Status And Future Pathways: A Case Study In Row Crop Production With Chatgpt, Nipuna Chamara, Yufeng Ge, Joe Luck, Yu Pan, Saleh Taghvaeian, Cory Walters, Christopher Proctor, Daran Rudnick, Daren Redfearn

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The agricultural decision-making process is experience-based, knowledge-dependent, time-sensitive, complex, and driven by historical data. Planting, fertilization, irrigation, and chemigation are key categories in farm decision-making, and currently there is no one-shot decision-support tool that covers all these activities. Generative Artificial Intelligence (AI) models are more advanced than traditional machine learning and deep learning models. These models have been trained on vast amounts of data from the internet, allowing them to accept unstructured data in various forms and generate human-like text, solutions to problems, and scenario predictions. Given this capability, we became interested in exploring the potential of generative AI in …

Construction Project Administration: Course Portfolio, Andre Messner

UNL Faculty Course Portfolios

This portfolio presents a structured framework for the design and implementation of a construction project administration course within a Construction Management program. Emphasis is placed on aligning student learning objectives, instructional strategies, and assessment methods with current industry expectations and professional standards. The course is intentionally designed to bridge the gap between theoretical knowledge and practical application by incorporating real-world scenarios, collaborative learning environments, and experiential activities that mirror industry practices.

In addition to outlining the course structure, this paper examines the pedagogical foundations that support student-centered learning, including constructivism, scaffolding, and project-based learning. These approaches are used to foster …

Optimization Of The Baffle Geometry Of A Circular Culvert Outlet Structure To Maximize Energy Dissipation, Kiarash Shirmahi

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

High-velocity flow at culvert outlets can lead to significant soil erosion and damage to downstream infrastructure, particularly in agricultural regions where land protection is critical. Circular culverts, commonly used in transportation systems, are especially susceptible to this issue due to flow acceleration caused by geometric constraints and installation angles. Despite extensive research on energy dissipation in rectangular culverts, limited attention has been given to circular configurations. This study addresses this gap by evaluating the hydraulic performance of baffle systems designed to reduce outlet energy in circular culverts.

A series of laboratory experiments was conducted using a scaled physical model of …

Exploring Determinants Of Value For Money And Bundling Effects On Public–Private Partnership Projects: A Data-Driven Empirical Study, Gaurav Khadka

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Public–private partnerships (P3s) are widely used to deliver public infrastructure, yet current understanding of what drives variation in Value for Money (VfM) and the effectiveness of project delivery strategies such as bundling remains largely conceptual and grounded in perception-based evidence. Consequently, governments lack empirically validated guidance on which project, financial, and macroeconomic conditions meaningfully influence VfM outcomes and whether bundling improves project performance within the P3 context. This study addresses these gaps through an integrated analysis of 180 Canadian P3 infrastructure projects (1992–2020), one of the most comprehensive datasets of realized VfM internationally, incorporating project characteristics, financial arrangements, and macroeconomic …

Problems With Small Drinking Water Systems In Developing And Developed Countries: How Do They Compare?, Kurt Kesteloot

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation compares the factors that drive the long-term functionality of small drinking water systems (serving fewer than 10,000 people) in developing and developed country contexts, with a focus on groundwater supplies. Using regression analysis in SAS and complementary fuzzy-set Qualitative Comparative Analysis (fsQCA) for developing countries, the study integrates two datasets: 23 Engineers Without Borders project surveys (90+ variables across 14 countries) and a multi-year National Park Service inspection dataset (approximately 1,561 systems; 7,460 recorded deficiencies, enriched with U.S. Census ZIP-code aggregates). In developing countries, statistically significant predictors of success include government cash contributions (odds ratio [OR] ≈ 67.6), …

Guidance For Left-Turn Flashing Yellow Arrow (Fya) Implementation In Nebraska, Aemal Khattak, Li Zhao, Frank Selase Dzawu

Nebraska Department of Transportation: Research Reports

This research evaluates the safety performance of flashing yellow arrows (FYA) and driver behavioral responses in Nebraska, using data from 324 FYA intersections (Lincoln 160; Omaha 164) to develop evidence-based implementation guidance. The study addresses critical knowledge gaps in local driver acceptance patterns, the effectiveness of phasing configurations, and a comprehensive safety assessment that integrates crash and conflict analyses. The methodology employed four complementary analyses: (1) negative binomial crash frequency modeling of 3945 unique left turn crashes (2015-2024) across Lincoln and Omaha; (2) binary logistic regression of 948 gap acceptance decisions across 43 intersections; (3) linear regression of post-encroachment time …

Update Of Intersection/Interchange Guidelines For Rural Expressways In Nebraska, Aemal Khattak, Mm Shakiul Haque

Nebraska Department of Transportation: Research Reports

Nebraska Department of Transportation (NDOT) staff frequently decide on changes to existing two-way stop- controlled (TWSC) intersections on rural expressway to alternative facilities, such as a restricted crossing U-turn (RCUT), a roundabout, a signalized intersection, or an interchange. As Nebraska makes progress toward completion of its expressway system, updated and defensible decision-making is essential for conversion of TWSC highway intersections. NDOT’s existing guidelines, developed in the 1990s, no longer reflect current operations, safety performance, or modern intersection designs.

This project updated and expanded NDOT’s guidance using contemporary traffic operational and safety data, combined with robust microsimulation and safety performance modeling. …

Ultra-High-Performance Concrete (Uhpc) For Bridge Deck Overlay And Structural Deck Repair, Jiong Hu, George Morcous, Akbota Aitbayeva, Ming Gerges

Nebraska Department of Transportation: Research Reports

Ultra-high-performance concrete (UHPC) is an advanced cementitious material known for its exceptional strength and durability, making it an ideal material for bridge deck overlays and repairs that address the common issue of premature deck deterioration. Conventional UHPC is typically flowable and self-leveling, which makes it unsuitable for deck surfaces with cross-slopes and/or sloped vertical profiles. Therefore, a highly thixotropic UHPC that responds well to vibration while remaining stable on sloped surfaces is needed for overlay applications. Mixtures with varying binder content, water-to-binder ratio, fiber content, and dosages of admixtures were developed and evaluated. Two of the most effective and economical …

Effect Of Curing Duration On Bridge Deck Concrete Performance, Zhaniya Omarova

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

This study evaluates the influence of curing duration on the performance of bridge deck concrete and investigates the feasibility of reducing curing periods without compromising structural and durability properties. Two concrete mixtures, a standard Nebraska Department of Transportation (NDOT) bridge deck mix (47BD) and an optimized reduced-cement-content mix (O47BD-R100), were evaluated under multiple curing durations Fresh, early-age, mechanical, durability, and shrinkage properties were assessed to characterize the effect of curing on concrete behavior. Internal relative humidity and temperature were monitored using embedded sensors to investigate moisture diffusion and its role in shrinkage development for lab specimens and full-scale slabs.

Results …

Feasibility Of Using Recycled Waste Plastic In Concrete Pavements In Nebraska, Amasi Hajahja, Jamilla Teixeira, George Morcous

Nebraska Department of Transportation: Research Reports

Waste plastic (WP) is a growing environmental concern due to its non-biodegradable nature, large-scale production, and harmful impact on natural resources. With nearly 75% of WP in the U.S. ending up in landfills, effective recycling strategies are urgently needed. In parallel, the limited availability of natural aggregates highlights the need for alternative materials in concrete construction. This study investigates the feasibility of using recycled waste plastic (RWP) in concrete mixtures, both as aggregates and fibers for rigid pavement applications in Nebraska. Concrete mixtures were prepared by partially replacing natural fine aggregates with recycled plastic aggregates (RPA) at replacement levels of …

Characterization Of Sediment Loads And Size Distribution In Nebraska Roadway Runoff, Bruce I. Dvorak, David M. Admiraal, Pavel Shrestha

Nebraska Department of Transportation: Research Reports

The Nebraska Department of Transportation (NDOT) must manage sediment, and pollutant loads from roadway runoff to meet stormwater regulations. The SAFL Baffle, a hydrodynamic separator used by NDOT, depends on reliable estimates of total suspended solids (TSS) and particle size distribution (PSD). However, limited data exists for Nebraska roadways. In this study stormwater runoff was monitored at four NDOT-maintained sites, two in Lincoln and two in Beatrice, over 1.5 years to characterize TSS and PSD and to evaluate SAFL Baffle performance using the SHSAM model. Results showed large variability across sites and seasons. Median TSS ranged from 158 to 580 …

Assessment Of Winter Maintenance Performance Objectives Using Maintenance Decision Support System, Curtis L. Walker, Mark R. Anderson, Aemal Khattak, Thomas Kauzlarich, Abdul Farhan

Nebraska Department of Transportation: Research Reports

It is important for transportation agencies to assess their winter maintenance operations performance to identify areas for improvement and/or resource investment to maintain optimal levels of service, mobility, and safety. This study explores nine winter snowstorms in Nebraska during the 2023-2024 winter season across 20 road segments, 12 of which were along the Interstate-80 corridor. Datasets explored include meteorological information, traffic mobility insights, winter maintenance operations activities, and road conditions before, during, and after the periods of accumulating snowfall. Statistical analyses explored correlations and quantitative relationships among these datasets, while visual dashboards were developed to promote more qualitative considerations of …

Design And Fabrication Of A Scaled Automated Dairy Farm Model: A Report, Md Towfiqur Rahman

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Summary

This study investigates how ventilation systems work in dairy barns and builds a scaled model to support education and research. The project is designed to help students from the University of Nebraska–Lincoln (UNL), K-12 learners, and researchers in animal science, veterinary medicine, and engineering gain visual experience with dairy facility components and processes. Different ventilation methods were studied, leading to the design of a 1/64-scale tunnel-ventilated dairy barn meant for 60 Holstein Friesian cows. Barn dimensions were set based on real Holstein cow measurements to ensure proper cow comfort, while airflow requirements were calculated and scaled down. Miniature fans …

Evaluation Of Critical Shear Strength Of Soils In Nebraska Based On Revised Cpt, Chung R. Song, Bashar Al-Nimri, Basil Abu Al Sha'r, Dhurba R. Pandey, Jongwan Eun, Seunghee Kim

Nebraska Department of Transportation: Research Reports

This study evaluated the “Fully Softened Shear Strength (FSSS)” of soils in Nebraska based on a revised Cone Penetration Test(CPT) method. FSSS is a unique strength condition that soils show substantially reduced strength during rainy seasons, eventually causing failure of slopes and other structures.

The revised CPT was adapted to inject water at targeted depths, inducing controlled moisture infiltration and capturing real-time soil softening over designated intervals of 30, 60, or 90 minutes. Through tip resistance (qc) and sleeve friction (fs) measurements under “in-situ” and “wet” conditions, the test effectively identified fully disturbed/low strength zones around the sleeve. Simultaneous sampling …

The Use Of Recycled Plastic In Asphalt Pavements: Feasibility Study, Isabella Bueno, Robert Rea, Jamilla Teixeira

Nebraska Department of Transportation: Research Reports

The plastics industry has been actively exploring new end-market opportunities for the more than 35 million tons of waste plastics generated annually. The use of recycled WP in asphalt presents an opportunity to improve pavement performance while reducing the growing amount of WP being landfilled or released into the environment. However, the use of WP in asphalt mixtures poses challenges due to variations in plastic composition and the presence of non-plastic contaminants. The absence of standardized procedures has resulted in inconsistent integration methods and unclear roles of WP within asphalt concrete (AC) mixtures. Therefore, the goal of this multiphase study …

Development And Evaluation Of Crashworthy Approach Guardrail Transition With Increased Span Length Between Concrete Bridge Rail And First Transition Post – Phase I, Tewodros Yosef, Qusai Alomari, Ronald K. Faller, Robert W. Bielenberg, Scott Rosenbaugh

Nebraska Department of Transportation: Research Reports

This study developed and evaluated a 34-in.-tall Nebraska Department of Transportation (NDOT) thrie-beam approach guardrail transition (AGT) with an increased span between the concrete buttress end and the first transition post. The objective was to accommodate a wide range of common obstructions near bridge ends, including abutments, wing walls, drainage features, and utilities. A survey of NDOT districts identified critical obstruction geometries and informed design criteria. Most NDOT districts indicated that a maximum span of about 4 ft would be sufficient, and some preferred spans up to 6 ft. To accommodate a wider range of obstructions, the first transition post …

Assessment Of Truck Parking Demand And Safety During Normal And Severe Weather Conditions In Nebraska, Nathan Huynh, Li Zhao, Zhenghong Tang, Aida Riahifar, Jahangeer Jahangeer

Nebraska Department of Transportation: Research Reports

This project examined truck parking capacity, demand, and utilization patterns along I-80 in Nebraska. The objectives were to (1) document the capacity of public and private truck parking facilities along I-80, (2) analyze spatial and temporal trends in parking demand, (3) develop models to predict occupancy at parking facilities, (4) identify clusters of undesignated parking during inclement weather, and (5) assess whether truck parking shortages contribute to truck-involved crashes. Within a one-mile buffer of I-80, 21 public facilities and 49 private facilities were identified. The spatiotemporal analysis of these public and private truck parking facilities using the National Agriculture Imagery …

Deep Learning Framework For Sow Posture Classification From Depth Images: Comparison With Data Transformation Techniques, Models, And Cross-Validation, Md Towfiqur Rahman, Tami M. Brown-Brandl, Gary A. Rohrer, Sudhendu R. Sharma, Suzanne M. Leonard, Yeyin Shi

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Piglet preweaning mortality (PWM) in the United States averages ≈14–15%, with sow overlaying causing about one third proportion of these losses. This research aimed to develop and evaluate deep learning models to classify six sow postures using depth images to monitor behaviors linked to overlaying risk. Top-down depth images were captured with Kinect V2^® cameras at 10 frames min^-1 for five consecutive days (2 days before to 2 days after farrowing), yielding 26,506 training images from 18 sows, 17,901 testing images from 12 sows, and 4,697 additional images from three sows in diagonal stalls for external validation. Three …

A Comparative Analysis Of Complete Streets And Multimodal Transport Approaches: Implications For Sustainable Urban Mobility In Lincoln, And Global Contexts, Oliva Richard Kilyenyi

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Movement of people and goods in urban areas through different modes of transportation including walking, cycling, public transit and by autos is termed as urban mobility. Urban mobility presents significant environmental, social, and economic challenges for cities worldwide as they grapple with the impacts of conventional transportation systems, particularly in North America context where car-centric planning approaches has dominated urban developments since 1950s. Car-centric dominance is 80% in North American Metropolitan areas (Manaugh et al., 2015). The impacts of these conventional systems include greenhouse gas emission emissions contributing approximately 24% of global carbon dioxide (CO₂) emissions, air pollution …

Ethical Decision-Making Processes In Authentic Environmental Engineering Contexts Through Systems Thinking And Team Collaboration Lenses: An Embedded Single Case Study, Toluwalase Eniola Brower

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Ethical and professional responsibility is a critical learning outcome emphasized in ABET accreditation. However, ethics instruction in engineering education often lacks integration of system-level considerations such as economic, environmental, and societal contexts, that are essential for developing engineering solutions that ensure the safety and welfare of diverse stakeholders. This embedded single-case study investigated the integration of authentic ethics instruction within a junior-level environmental engineering course at a Midwestern U.S. university during spring 2025 and explores how civil engineering student teams within the course engage in ethical decision-making process during authentic problem-solving.

The instructional intervention consisted of four problem-based ethics modules, …

Rainfall-Runoff Modelling In An Indonesian Humid Tropical Area Using Satellite-Based Precipitation Products, Noordiah Helda

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation explores three rainfall-runoff models in the humid tropical regions of Indonesia using satellite-based precipitation products (SBPPs) and develops integrated machine-learning modeling frameworks. Several ground-based observations from BMKG (Badan Meteorologi, Klimatologi, dan Geofisika (also known as the Indonesian Agency for Meteorology, Climatology, and Geophysics)) stations across Indonesia (133−165 stations) are compared and evaluated against satellite products, indicating that GPM performs well, with R-squared values ranging from 0.54 to 0.76 and correlation coefficients ranging from 0.45 to 0.69, respectively.

In the Martapura Watershed, South Kalimantan, due to a lack of observational discharge data, streamflow was generated using the FJ Mock …

Large-Scale Experimental Study On The Impact Of Air Cleaning & Ventilation On Indoor Air Quality And Student Illness-Related Absenteeism, Daud Nosham

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This large-scale randomized experimental field study investigated the effect of portable air purifiers (PAPs) on classroom’s air quality and student’s illness related absenteeism. PAPs were installed in 317 classrooms from various school districts located in Eastern Nebraska. The classrooms were randomly assigned into four conditions: three treatment conditions (T1, T2 & T3) and one control condition (device without any filter). T1 was equipped with HEPA filters, T2 added Activated Carbon (AC) layer to HEPA, and T3 further integrated Germicidal Ultraviolet (GUV) alongside HEPA and AC filters. The measured variables were carbon dioxide (CO2), fine particles (PN2.5) and coarse particles (PNcoarse), …

Occurrence Of Per And Polyfluoroalkyl Substances In Rural Wastewater Treatment Plants And Comparison To Large Treatments Plants, Madeleine Rauhauser

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Per and polyfluoroalkyl substances (PFAS) are a class of compounds defined by their carbon – fluorine bonds, which are incredibly strong. The strength of this bond makes these compounds very useful industrially, they are used as waterproof and grease proof coatings, and as fire retardants. The same thing that makes them useful industrially makes them incredibly recalcitrant in the environment, it is difficult to destroy these compounds. PFAS are also suspected to cause health impacts in people, such as kidney cancer and low birth weights. Wastewater has been commonly identified as a contributor to the amount of PFAS in the …

Exploring Transformative Learning Experiences In Engineering Doctoral And Post-Doctoral Education: Developing Non-Technical Competencies For Early-Career Academic Roles, Ibukunoluwa Eunice Salami

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation explores the transformative learning experiences that early-career engineering faculty recounted from their doctoral and postdoctoral training and how these experiences shaped the development of non-technical competencies essential for academic success. Grounded in Mezirow’s Transformative Learning Theory (TLT) and the Competency-Based Professional Development Framework (CBPDF), the study examines how reflection and shifts in frames of reference supported competency growth and faculty readiness. A qualitative holistic single-case study design was employed. Data sources included semi-structured interviews with early-career engineering faculty and program learning objectives drawn from graduate handbooks. Data analysis was both deductive and inductive guided by Mezirow’s ten phases …

The Impact Of Relative Bridge Width On Highway Crashes In Nebraska, Mujahid Ali Bahadur

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

This research examines how bridge width relative to the approach roadway affects crash occurrence on Nebraska highways. The Nebraska Department of Transportation-(NDOT) Bridge Design Manual sets minimum bridge widths based on roadway classification, traffic projections, and the American Association of State Highway and Transportation Officials’ (AASHTO) Load and Resistance Factor Design (LRFD) criteria. While these guidelines ensure structural and functional adequacy, they do not incorporate safety performance analyses based on crash data. This leaves an important gap in understanding how bridge and approach roadway width decisions influence safety outcomes.

This research has four objectives: (1) evaluate crash frequency across different …

Characterization Of Sediment Loads And Size Distribution In Nebraska Roadway Runoff, Pavel Shrestha

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The Nebraska Department of Transportation (NDOT) must manage sediment and pollutant loads from roadway runoff to meet stormwater regulations for discharges into impaired waters. The SAFL Baffle, a hydrodynamic separator used by NDOT, depends on accurate estimates of total suspended solids (TSS) and particle size distribution (PSD). However, existing studies show large variability in these characteristics, limiting their relevance to Nebraska roadways.

This study monitored stormwater runoff for 1.5 years at four NDOT-maintained sites—two in Lincoln and two in Beatrice—that received runoff from areas outside the roadway right-of-way. The SAFL Baffle was evaluated using the SHSAM (Sizing Hydrodynamic Separators and …

Repair/Preservation Of Concrete Compression Members In Bridges Using Ultra-High-Performance Concrete (Uhpc), Mohammed Hedia, George Morcous

Nebraska Department of Transportation: Research Reports

As of 2024, approximately 36% of bridges across the United States require repair or replacement, with 7% classified as structurally deficient. The estimated cost to address these deficiencies exceeds $260 billion. In recent years, Ultra-High-Performance Concrete (UHPC) has emerged as a repair material for infrastructure preservation, drawing increased attention from transportation agencies and researchers worldwide. The Federal Highway Administration (FHWA) has notably advocated for UHPC’s adoption in bridge preservation initiatives, recognizing its exceptional mechanical properties and durability.

This report presents a comprehensive literature review on the application of UHPC as a repair and strengthening material for bridge compression members. While …

Evaluation Of Performance Characteristics And Groundwater Contamination Risks Associated With On-Farm Swine Carcass Disposal Via Composting And Shallow Burial With Carbon, Gustavo Castro Garcia

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

This dissertation evaluates the performance of three on-farm swine carcass disposal methods: whole carcass composting (WCC), ground carcass composting (GCC), and shallow burial with carbon (SBC), focusing on biosecurity factors and groundwater contamination risks. Foreign animal diseases (FADs), such as African swine fever and classical swine fever, pose severe economic and animal well-being risks if introduced to the United States. With confirmation of an FAD, swine movement will be halted, creating an urgent need for practical, biosecure, and environmentally responsible on-farm disposal strategies for swine carcasses. Nebraska, as a leading swine-producing state, exemplifies the vulnerability of high-density livestock regions to …

Resilience Of Interdependent Transportation And Healthcare Systems: A Simulation-Driven Framework Incorporating Social Equity And Facility Optimization, S. Yasaman Ahmadi

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The overarching goal of this dissertation is to develop an integrated, simulation-driven framework to assess and enhance the resilience of interdependent transportation and healthcare systems before, during, and after natural hazards. By examining how spatial disruptions, social vulnerability, operational constraints, and infrastructure interdependencies affect access to and functionality of hospitals, this research offers a multifaceted evaluation of system performance under stress. This dissertation examines the impact of natural hazards, particularly floods, on the interdependent transportation and healthcare systems. The proposed approach combines and advances GIS-based network analysis, graph-theoretical modeling, and discrete-event simulation to evaluate system performance under different scenarios. The …

Development Of A Machine Learning Framework For An Irrigation Decision Support System, Eric Wilkening, Derek M. Heeren, Yeyin Shi, Laila A. Puntel, Guillermo R. Balboa, Abia Katimbo, Kuan Zhang, Precious Nneka Amori, Bruno Lena

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Currently used irrigation scheduling techniques often require significant human intervention and are time consuming, particularly for variable rate irrigation. This research aimed to develop a conceptual framework that incorporates disparate data sources leveraging both mechanistic and machine learning (ML) approaches. The overarching objective is to utilize the growing availability of data and technology to manage irrigation more precisely, which will minimize negative impacts of irrigation on our water resources. An initial irrigation machine learning model was proposed and tested in this study as a key component of an edge-cloud computing and federated learning decision-making framework. The specific objectives were (1) …