Open Access Publications

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Open access publications by faculty, postdocs, and graduate students in the Department of Civil and Environmental Engineering.

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Abiotic reduction of 3-nitro-1,2,4-triazol-5-one (NTO) and other munitions constituents by wood-derived biochar through its rechargeable electron storage capacity
(Environmental Science: Processes and Impacts, 2022-01-17) Xin, Danhui; Girón, Julián; Fuller, Mark E.; Chiu, Pei C.
The environmental fate of 3-nitro-1,2,4-triazol-5-one (NTO) and other insensitive munitions constituents (MCs) is of significant concern due to their high water solubility and mobility relative to legacy MCs. Plant-based biochars have been shown to possess a considerable electron storage capacity (ESC), which enables them to undergo reversible electron transfer reactions. We hypothesized biochar can act as a rechargeable electron donor to effect abiotic reduction of MCs repeatedly through its ESC. To test this hypothesis, MC reduction experiments were performed using wood-derived biochars that were oxidized with dissolved oxygen or reduced with dithionite. Removal of aqueous NTO, an anion at circumneutral pH, by oxidized biochar was minimal and occurred through reversible adsorption. In contrast, NTO removal by reduced biochar was much more pronounced and occurred predominantly through reduction, with concomitant formation of 3-amino-1,2,4-triazol-5-one (ATO). Mass balance and electron recovery with ferricyanide further showed that (1) the amount of NTO reduced to ATO was relatively constant (85–100 μmol per gram of biochar) at pH 6–10; (2) the fraction of biochar ESC reactive toward NTO was ca. 30% of that toward ferricyanide; (3) the NTO-reactive fraction of the ESC was regenerable over multiple redox cycles. We also evaluated biochar transformation of other MCs, including nitroguanidine (NQ), 2,4-dinitroanisole (DNAN), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). While mass and electron balances could not be established due to sorption, DNAN and RDX reduction by reduced biochar was confirmed via detection of multiple reduction products. In contrast, NQ was not reduced under any of the conditions tested. This study is the first demonstration of organic contaminant degradation through biochar's rechargeable ESC. Our results indicate biochar is a regenerable electron storage medium and sorbent that can remove MCs from water through concurrent reduction and sorption, and is thus potentially useful for pollution control and remediation at military facilities.
Aggregated Zero-Knowledge Proof and Blockchain-Empowered Authentication for Autonomous Truck Platooning
(IEEE Transactions on Intelligent Transportation Systems, 2023-05-10) Li, Wanxin; Meese, Collin; Guo, Hao; Nejad, Mark
Platooning technologies enable trucks to drive cooperatively and automatically, providing benefits including less fuel consumption, greater road capacity, and safety. To establish trust during dynamic platooning formation, ensure vehicular data integrity, and guard platoons against potential attackers in mixed fleet environments, verifying any given vehicle’s identity information before granting it access to join a platoon is pivotal. Besides, due to privacy concerns, truck owners may be reluctant to disclose private vehicular information, which can reveal their business data to untrusted third parties. To address these issues, this is the first study to propose an aggregated zero-knowledge proof and blockchain-empowered system for privacy-preserving identity verification in truck platooning. We provide the correctness proof and the security analysis of our proposed authentication scheme, highlighting its increased security and fast performance. The platooning formation procedure is re-designed to seamlessly incorporate the proposed authentication scheme, including the 1st catch-up and cooperative driving steps. The blockchain performs the role of verifier within the authentication scheme and stores platooning records on its digital ledger to guarantee data immutability and integrity. In addition, the proposed programmable access control policies enable truck companies to define who is allowed to access their platoon records. We implement the proposed system and perform extensive experiments on the Hyperledger platform. The results show that the blockchain can provide low latency and high throughput, the aggregated approach can offer a constant verification time of 500 milliseconds regardless of the number of proofs, and the platooning formation only takes seconds under different strategies. The experimental results demonstrate the feasibility of our design for use in real-world truck platooning.
Application of New Lubricant and Modifier Formulations for the Reduction of Wheel Squeal Noise Under Freight and Passenger Service
(American Railway Engineering Association, 1999-09) Zarembski, Allan M.; Chiddick, Kelvin S.
Wheel sequel noise on curved track is a serious problem in residential areas where the tracks are near or adjacent to homes and residences. This was the case in a Southern California community that was adjacent to a Southern Pacific Railroad mainline that carried both freight and passenger traffic. The specific wheel squeal problem was associated with the negotiation of the moderate curved track by the mix of traffic at a range of speeds and operating conditions. While significant noise levels were recorded by all of the traffic, to include commuter and inter-urban passenger traffic, the highest levels of noise were recorded by intermodal freight equipment, both trailer and container carrying. These n0ise levels were of significant magnitude and resulted in numerous complaints as well a'$ follow up lawsuits from the residents. In order to address this noise problem, the dynamics of the wheel/rail interaction mechanism was examined and a two part solution applied. The solution consisted of using a low coefficient of friction modifiers on the gage face of the high rail of the curve(s) in conjunction with a high positive coefficient of friction modifiers on the top of the rail head on both the high and low rails. In this configuration, lateral slip of the wheel tread across the rail head was significantly reduced, together with the more traditional flanging effects 011 the gage face of the high rail. The result was a significant reduction in the level of noise generated by all of the traffic types. In order to achieve this dual application at specific locations on the rail head, a high rail vehicle mounted application system was developed and utilized. The hi-rail based system allowed for a uniform and accurate application of the friction modifiers onto the rail. However, the friction modifiers deteriorated with time and traffic (as a function of the number of axle passes), and as such had to be reapplied on a regular and ongoing basis. This paper describes the development and application of this combination of friction modifiers to the high noise curve(s) as well as the determination of the rate of degradation of the friction modifiers under traffic. The testing of the Friction Modifiers (Lubricants) performance led to the development of a well defined friction modifier effectiveness degradation curve which served as the basis for an ongoing program of friction modifiers aimed at keeping the level of noise below a defined threshold. In addition, the need for a "reasonably long" interval between friction modifier applications led to the development of an extended life version of the friction modifiers that made them appropriate for use in an ongoing maintenance application.
Backed-Up, Saturated, and Stagnant: Effect of Milldams on Upstream Riparian Groundwater Hydrologic and Mixing Regimes
(Water Resources Research, 2022-09-28) Sherman, Melissa; Hripto, Johanna; Peck, Erin K.; Gold, Arthur J.; Peipoch, Marc; Imhoff, Paul; Inamdar, Shreeram
How milldams alter riparian hydrologic and groundwater mixing regimes is not well understood. Understanding the effects of milldams and their legacies on riparian hydrology is key to assessing riparian pollution buffering potential and for making appropriate watershed management decisions. We examined the spatiotemporal effects of milldams on groundwater gradients, flow directions, and mixing regime for two dammed sites on Chiques Creek, Pennsylvania (2.4 m tall milldam), and Christina River, Delaware (4 m tall dam), USA. Riparian groundwater levels were recorded every 30 min for multiple wells and transects. Groundwater mixing regime was characterized using 30-min specific conductance data and selected chemical tracers measured monthly for about 2 years. Three distinct regimes were identified for riparian groundwaters—wet, dry, and storm. Riparian groundwater gradients above the dam were low but were typically from the riparian zone to the stream. These flow directions were reversed (stream to riparian) during dry periods due to riparian evapotranspiration losses and during peak stream flows. Longitudinal (parallel to the stream) riparian flow gradients and directions also varied across the hydrologic regimes. Groundwater mixing varied spatially and temporally between storms and seasons. Near-stream groundwater was poorly flushed or mixed during storms whereas that in the adjacent swales revealed greater mixing. This differential groundwater behavior was attributed to milldam legacies that include: berm and swale topography that influenced the routing of surface waters, varying riparian legacy sediment depths and hydraulic conductivities, evapotranspiration losses from riparian vegetation, and runoff input from adjoining roads. Key Points: - Milldams raise riparian groundwater levels, decrease hydraulic gradients, and cause reversals in groundwater flow - Milldam legacies contribute to reduced groundwater mixing in near-stream sediments - Altered groundwater regimes due to milldams could affect riparian water quality processes Plain Language Summary: Riparian zones can buffer streams from upland nitrogen pollution and are thus considered as important water quality management practices. How the presence of milldams affects groundwater flow paths and their buffering capacity is not known. This study showed that milldams back up stream water above dams, reduce the groundwater gradients from the upland to the stream, and also result in their reversal during summer dry conditions and floods. Milldams reduced the mixing of groundwaters for near-stream sediments. This response was attributed to the topographic and sediment conditions associated with the milldams.
Biochar and zero-valent iron sand filtration simultaneously removes contaminants of emerging concern and Escherichia coli from wastewater effluent
(Biochar, 2023-07-19) Zhu, Linyan; Chattopadhyay, Suhana; Akanbi, Oluwasegun Elijah; Lobo, Steven; Panthi, Suraj; Malayil, Leena; Craddock, Hillary A.; Allard, Sarah M.; Sharma, Manan; Kniel, Kalmia E.; Mongodin, Emmanuel F.; Chiu, Pei C.; Sapkota, Amir; Sapkota, Amy R.
Advanced treated municipal wastewater is an important alternative water source for agricultural irrigation. However, the possible persistence of chemical and microbiological contaminants in these waters raise potential safety concerns with regard to reusing treated wastewater for food crop irrigation. Two low-cost and environmentally-friendly filter media, biochar (BC) and zero-valent iron (ZVI), have attracted great interest in terms of treating reused water. Here, we evaluated the efficacy of BC-, nanosilver-amended biochar- (Ag-BC) and ZVI-sand filters, in reducing contaminants of emerging concern (CECs), Escherichia coli (E. coli) and total bacterial diversity from wastewater effluent. Six experiments were conducted with control quartz sand and sand columns containing BC, Ag-BC, ZVI, BC with ZVI, or Ag-BC with ZVI. After filtration, Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated more than 90% (> 1 log) removal of E. coli from wastewater samples, while BC, Ag-BC, BC with ZVI and Ag-BC with ZVI also demonstrated efficient removal of tested CECs. Lower bacterial diversity was also observed after filtration; however, differences were marginally significant. In addition, significantly (p < 0.05) higher bacterial diversity was observed in wastewater samples collected during warmer versus colder months. Leaching of silver ions occurred from Ag-BC columns; however, this was prevented through the addition of ZVI. In conclusion, our data suggest that the BC with ZVI and Ag-BC with ZVI sand filters, which demonstrated more than 99% removal of both CECs and E. coli without silver ion release, may be effective, low-cost options for decentralized treatment of reused wastewater. Graphical Abstract available at: https://doi.org/10.1007/s42773-023-00240-y Highlights - The efficacy of BC, Ag-BC, and ZVI sand filtration, and their combinations, in removing contaminants from reused water was evaluated. - Ag-BC, ZVI, BC with ZVI and Ag-BC with ZVI demonstrated > 90% removal of E. coli. - BC, Ag-BC, BC with ZVI and Ag-BC with ZVI demonstrated efficient removal of selected contaminants of emerging concern.
Biophysical flocculation reduces variability of cohesive sediment settling velocity
(Communications Earth & Environment, 2023-04-24) Ye, L.; Penaloza-Giraldo, J. A.; Manning, A. J.; Holyoke, J.; Hsu, T.-J.
Biophysical cohesion, introduced predominantly by Extracellular Polymeric Substances (EPS) during mineral flocculation in subaqueous environments, plays important role in morphodynamics, biogeochemical cycles and ecosystem processes. However, the mechanism of how EPS functioning with cohesive particles and affects settling behaviors remain poorly understood. We measure initial flocculation rate, floc size and settling velocity of mineral and artificial EPS (Xanthan gum) mixtures. Combining results from these and previous studies demonstrate coherent intensification of EPS-related flocculation compare with those of pure mineral and oil-mineral mixtures. Importantly, the presence of EPS fundamentally changes floc structure and reduces variability of settling velocity. Measured data shows that ratios of microfloc and macrofloc settling velocity for pure mineral flocs is 3.9 but greatly reduced to a lowest value of 1.6 due to biological EPS addition. The low variability of settling velocity due to EPS participation explains the seemingly inconsistent results previously observed between field and laboratory studies.
Bladder expandable robotic system and UV materials for rapid internal pipeline repair
(SAMPE Conference Proceedings 2023, 2023-04-18) Tierney, John J.; Vanarelli, Alex; Fuessel, Lukas; Abu-Obaid, Ahmad; Sauerbrunn, Steve; Das, Shagata; Deitzel, Joseph; Tatar, Jovan; Heider, Dirk; Shenton, Harry W. III; Kloxin, Christopher J.; Sung, Dae Han; Thostenson, Erik; Gillespie, John W. Jr.
This paper describes a novel composite placement process to fabricate stand-alone structural pipe within existing legacy pipelines—with no disruption in gas service. The process utilizes low-cost, UV-curable, glass fiber reinforced plastics (GFRP) for discrete preforms made from continuous fiber fabrics. These sections are designed to meet 50-year service life by addressing the unique loading conditions of the pipe repair allowing for the design customization of the preforms to accommodate the state of pipe corrosion, access points or other local features that may vary along the length of the pipe. The approach offers maximum design flexibility and customization while minimizing installation time and cost. The preforms are fabricated above ground using rapid automated manufacturing methods for quality control. The preforms are transported by a tethering system to the robot. The robot is comprised of a self-propelled dual inflation expandable bladder system that places, consolidates, and cures standard or custom composite sections along the entire pipe length in a continuous co-cure process. This system is designed to adapt to pipe features that include lateral tees, service connections, joints, gaps, and irregular cross sections. In addition, variable thickness composite sections can be placed along the pipe where exposed to high external loads under railroads, highways, airports or where soil erosion and movement occurs. This paper presents the robot design, assessment of UV curable resins, embedded sensing methods, and fabrication of pipe sections with this system.
Block-structured, equal-workload, multi-grid-nesting interface for the Boussinesq wave model FUNWAVE-TVD (Total Variation Diminishing)
(Geoscientific Model Development, 2022-07-18) Choi, Young-Kwang; Shi, Fengyan; Malej, Matt; Smith, Jane M.; Kirby, James T.; Grilli, Stephan T.
We describe the development of a block-structured, equal-CPU-load (central processing unit), multi-grid-nesting interface for the Boussinesq wave model FUNWAVE-TVD (Fully Nonlinear Boussinesq Wave Model with Total Variation Diminishing Solver). The new model framework does not interfere with the core solver, and thus the core program, FUNWAVE-TVD, is still a standalone model used for a single grid. The nesting interface manages the time sequencing and two-way nesting processes between the parent grid and child grid with grid refinement in a hierarchical manner. Workload balance in the MPI-based (message passing interface) parallelization is handled by an equal-load scheme. A strategy of shared array allocation is applied for data management that allows for a large number of nested grids without creating additional memory allocations. Four model tests are conducted to verify the nesting algorithm with assessments of model accuracy and the robustness in the application in modeling transoceanic tsunamis and coastal effects.
BNSF Tests Risk-Based Ultrasonic Detection
(Railway Track & Structures Magazine, 2001-02) Palese, J. W.; Zarembski, Allan M.; Patel, P. K.
As the railroad industry continues its focus on increased safety, rail defects and resulting rail caused derailments, have become an important area of interest. Analysis of FRA statistics on reportable mainline derailments, attributed to rail defects, shows an overall industry increase in reported derailments per billion gross ton mile (BGTM) of 4% in the period 1997 to 1999 [1,2]. This trend is illustrated in Figure 1 together with the corresponding increase in the average cost of rail related derailments for that same time period of more than 40%. Examining the FRA derailment data further, Figure 2 shows the distribution of derailments by rail defect type along with the average cost of derailment for that defect type. This figure clearly shows that the most predominant cause of rail related derailments is the transverse defect or TD class of defects, with the Detail Fracture (DF) representing the second most common cause of rail related derailments. For the entire range of rail defects, the average derailment cost varied from $200,000 to $1,400,000 depending on defect type, with an overall average of the order of $400,000. Note, this is FRA reportable cost only, the actual cost of the derailment, which could include loss of lading, train delays, or train rerouting, can be double that amount. This increasing trend in rail related derailments suggests that there is a need for improved rail maintenance and/or inspection practices to prevent the occurrence of these defects or to find the defects before they cause these expensive derailments. These improvements can take several forms, to include more aggressive rail replacement or maintenance practices or improved rail testing equipment. However, the focus of this article is on a easier to implement approach, one that can be applied almost immediately with a relatively modest impact on a railroad’s maintenance of way budget, specifically the improvement in the scheduling of conventional rail test equipment. As rail accumulates tonnage, it tends to develop more internal fatigue defects, based on various factors such as metallurgy of the rail, traffic (to include such factors as axle loading and speed), track support conditions, etc. This behavior is illustrated in Figure 3. As defects occur more frequently, it becomes important to test more frequently in order to insure that internal defects can be located and replaced before they have the opportunity to propagate to failure, and possibly result in a derailment. Earlier studies have indicated that approximately 1.3 derailments occur per thousand defects (detected plus service), thus highlighting the importance of matching test frequency to the rate of defect occurrence [3]. Simplistic rail test scheduling approaches, such as those based on annual tonnage levels, which do not account for aging rails and corresponding increased defects, do not give the railroad the flexibility to adjust test frequency to the actual rail conditions encountered. Likewise, simplified “rules of thumb” for scheduling ultrasonic testing, while often accounting for such factors as age of rail (usually in cumulative MGT) annual traffic density, class of track, type of traffic, defect counts, etc., do not do so in a manner that is directly tied into the “risk” of a derailment occurring. Rather, it is necessary to have a risk based scheduling methodology which makes use of site specific and directly measurable performance parameters that, in turn, can be related to a defined level of risk. Such a methodology was developed by US Department of Transportation Center Volpe National Transportation Systems Center [4], and further enhanced by ZETA-TECH Associates, Inc. [5].
Burlington Northern's Assessment of the Economics of High Capacity/ Heavy Axle Load Cars
(American Railway Engineering Association, 1990-05) Zarembski, Allan M.; Newman, R. R.; Resor, R. R.
North American freight cars and trains have been growing heavier for many years. For the most part this has been a response to competitive pressures, the inflexible nature of train crew costs, and the changing mix of traffic. The shift in traffic towards bulk commodities and unit trains (grain, coal, ore, and aggregates) was one manifestation of this change in traffic mix and its consequent movement toward heavier cars. Figure I shows graphically the near doubling of average car capacity since 1929. This trend to heavier cars has been accompanied by considerable research into the costs and benefits of larger cars and heavier trains. In particular, the issue of increasing car size, and consequently increasing axle loads, has been the subject of much examination and discussion. There s also the related issue of increasing the loading of existing cars. This issue was raised in 1986 at the Third International Heavy Haul Railways Conference (I) attended by representatives of Burlington Northern's Research & Development Department. In the opening paper of the conference, representatives of Mt. Newman Mining Co. and BHP Melbourne Research Laboratories stated that heavier axle loads were not only technically feasible but were also economically feasible under the conditions as experienced, tested, and applied in Australian heavy haul operations. This paper emphasized that since existing ore cars were only loaded to about 75% capacity, axle loads could be further increased. Following the First International Heavy Haul Railways Conference in 1978, axle loads were increased by the Australians to 33 tonnes (36.3 tons) and this axle load was adopted as a system wide standard. The successful gain led to adoption of an additional axle load increase to 35 tonnes (38.5 tons). Even higher axle loads appeared economically justifiable; however, the 35 tonnes provided an additional margin of comfort below the 37 tonnes (40.7 tons) level at which the Australian road's studies indicated that major, cost-impacting bridge upgradings would be required. As illustrated in Figure 2, the main point of the Australian findings was that axle loads between 33 and 37 tonnes (36 and 41 tons) were expected to reduce total railway maintenance and replacement costs. Costs were reduced 1-4% by increasing axle loads from 36 to 40 tons but began increasing beyond that point. In many ways, BN's Northern Coal Route is similar to the Mt. Newman Railway. It is composed almost entirely of welded rail, the bulk of it being 132 1b. section. Locomotive-borne lubrication is used and profile grinding of the rail is carried out twice per year. The vast majority of the traffic on the line is unit coal traffic. However, since BN's Northern Coal route is not an isolated captive railway, maintenance standards for both track and structures may be less rigorous. Mixed traffic and bridges of varying age and capacity present problems not encountered by the Australian railways.
Causality between fluid motions and bathymetric features
(Journal of Fluid Mechanics, 2022-02-07) Hsu, Tian-Jian
Can morphodynamic problems be solved using a first-principles approach in multiphase fluid mechanics? This is the holy grail for many sediment transport researchers but has yet to be achieved in practice. Using a fully resolved direct numerical simulation for turbulent flow over a bed of spheres, the study of Scherer et al. (J. Fluid Mech., vol. 930, 2022, A11) investigates the onset of morphodynamics from a statistically flat bed. The study shows that the formation of streamwise-aligned sediment ridges is due to large-scale turbulent streaks in the logarithmic layer, which drives local sediment sweeps and bursts. The study provides a solid physical justification for introducing initial perturbations in other reduced-complexity models and opens up new perspectives for simulating sediment transport and morphodynamic problems using high-fidelity models.
Coastal topography and hydrogeology control critical groundwater gradients and potential beach surface instability during storm surges
(Hydrology and Earth System Sciences, 2022-12-02) Paldor, Anner; Stark, Nina; Florence, Matthew; Raubenheimer, Britt; Elgar, Steve; Housego, Rachel; Frederiks, Ryan S.; Michael, Holly A.
Ocean surges pose a global threat for coastal stability. These hazardous events alter flow conditions and pore pressures in flooded beach areas during both inundation and subsequent retreat stages, which can mobilize beach material, potentially enhancing erosion significantly. In this study, the evolution of surge-induced pore-pressure gradients is studied through numerical hydrologic simulations of storm surges. The spatiotemporal variability of critically high gradients is analyzed in three dimensions. The analysis is based on a threshold value obtained for quicksand formation of beach materials under groundwater seepage. Simulations of surge events show that, during the run-up stage, head gradients can rise to the calculated critical level landward of the advancing inundation line. During the receding stage, critical gradients were simulated seaward of the retreating inundation line. These gradients reach maximum magnitudes just as sea level returns to pre-surge levels and are most accentuated beneath the still-water shoreline, where the model surface changes slope. The gradients vary along the shore owing to variable beach morphology, with the largest gradients seaward of intermediate-scale (1–3 m elevation) topographic elements (dunes) in the flood zone. These findings suggest that the common practices in monitoring and mitigating surge-induced failures and erosion, which typically focus on the flattest areas of beaches, might need to be revised to include other topographic features.
Combustion operating conditions for municipal Waste-to-Energy facilities in the U.S.
(Waste Management, 2021-08-01) Giraud, Robert J.; Taylor, Philip H.; Huang, Chin-pao
Highlights • Survey of U.S. municipal waste-to-energy (WTE) facilities identified 188 boilers. • These WTE boilers were stratified into nine categories by combustion technology. • WTE boilers typically operate at a gas residence time > 2.4 s above 1160°C. Abstract This paper reports the first known comprehensive survey of combustion operating conditions across the wide range of municipal waste-to-energy facilities in the U.S. The survey was conducted in a step-wise fashion. Once the population of 188 units operating at over 70 facilities was defined, this population was stratified by distinguishing characteristics of combustion technology. Stratum-level estimates for operating conditions were determined from data collected in the survey. These stratum-level values were weighted by corresponding design capacity share and combined to infer national-level operating parameter estimates representative of the overall population. Survey results show that typical municipal waste-to-energy combustion operating conditions in the U.S. are (1) furnace temperature above 1160 °C, (2) gas residence time above 2.4 s, (3) exit gas concentrations of nearly 10% for oxygen (dry basis), and (4) over 16% for moisture. These operating parameter values can serve as benchmarks for laboratory-scale studies representative of municipal waste-to-energy combustion as typically practiced in the U.S. Graphical abstract Available at: https://doi.org/10.1016/j.wasman.2021.07.015
Comparative Analysis of Static and Dynamic Tests of Piles in Difficult Soil Conditions of Kazakhstan
(International Journal for Computational Civil and Structural Engineering, 2022-06-24) Zhussupbekov, Ascar Zh.; Yessentayev, Ascar U.; Kaliakin, Victor N.; Drozdova, Irina V.
A comparative analysis of the results of field tests to determine the bearing capacity of a pile at the facilitys in the Nur-Sultan city and Petropavlovsk city. The aim of the study was to carry out a comparative analysis of the results of dynamic and static tests in the two construction site in order to identify the difference in performance. This article provides programs and results of tests with static indentation load and dynamic load on a pile in different two of the construction site under different soil conditions. The results of the comparative analysisare the following: Dynamic tests are needed for a preliminary assessment of the dynamic bearing capacity and the possibility of driving piles in different soil conditions. The bearing capacity of the pile, determined by dynamictests, is slightly lower than during static tests, the difference between the results is 11 and 17%.
Computerized Maintenance Planning and Reporting Systems
(1995-06) Zarembski, Allan M.
Concrete vs. Wood Ties: Making the Economic Choice
(1993-10) Zarembski, Allan M.
Track components must satisfy two basic criteria for acceptance. The first criterion is a performance criterion, which addresses whether the component has sufficient "strength" to function and survive in the railway environment. The second criterion in the economic one, whether the cost of the component is economic with respect to other similar components or products. This second criterion comes into play only if the first is satisfied, i.e., the component or system must have adequate performance, before its relative economics is even considered. Only when that performance criterion is met, the economic criterion comes into play. One clear application of this approach is that of the cross- ties and fastener systems, specifically that of the concrete cross-tie as compared to the traditional wood cross-tie that has been used by railroads for over two hundred years. While concrete tie designs have been around for many years, it has only been in the last two decades that their performance has been deemed to be adequate to withstand the severe loading environment of North American freight operations. Once this performance criterion has been satisfied, i.e., once it has been established that the concrete cross-ties can function and survive in the heavy haul environment, then the economics of this alternate tie system enters into the consideration of railway engineers. Specifically, the relative economics or the concrete tie system must be compared with the existing conventional systems, wood ties with cut spikes. In addition, the relative economic of these systems would have to be compared with several other technically proven systems, such as wood ties with alternate (elastic) fastening systems. This economic comparison, however, is not a simple matter. Because different tie/fastener systems exhibit different lives, require different maintenance activities, and affect other maintenance activities differently, simple comparison of the initial or "first" cost is not adequate. Rather, a comprehensive comparison of the costs and benefits of the alternate systems over their entire service lives is required, i.e., a "life cycle" cost analysis. This is further complicated by the fact that component lives and behavior vary significantly as a function of track and traffic characteristics, as well as individual railroad practices. Thus, the relative economics of these alternate cross-tie systems is not fixed, but vary with many of the operating and maintenance parameters. One approach that has been effectively used to address these significant differences is the development of life cycle costing computer models that can be run on personal computers. This approach led to several such models, such as the SelecTie model developed by ZETA-TECH Associates, Inc. for the Railway Tie Association. Such a model is capable of incorporating a comprehensive analytical methodology and allow for the ready (and rapid) changing of key parameters and the "instantaneous" recalculation of the results. This approach has been found to ZETA-TECH Associates, Inc. 2 1993 be an effective means of carrying out economic benefit comparisons, particularly ~such life cycle benefit analyses. The basic analytical approach used in this methodology (and in the model itself) is a present worth analysis approach, in which all the costs associated with the two alternative systems are examined and compared in terms of a "present worth". Thus, any future costs or savings associated with the two systems are brought to the present, and the "worth" of these future costs calculated using an appropriate interest rate. (Thus, taking into account the time value of money.)
Controlling Rail and Wheel Wear on Commuter Operations
(American Railway Engineering Association, 1993-10) Bohara, A. P.; Zarembski, Allan M.
The Regional Railroad Division of the Southeastern Pennsylvania Transportation Authority (SEPTA) operates approximately 450 route miles of commuter operation in the Philadelphia metropolitan area. In 1991, the railroad division began experiencing an unusually high rate of wheel and rail wear, particularly on sharp curves on the commuter rail lines. This wear was predominately wheel flange/rail gage face wear with an apparent correlation between the increase in wear on both the wheels and the rails. The cause of the increase in wear was not clear or well defined, and as a result the most appropriate form(s) of corrective action was difficult to determine. In order to effectively address this issue, a comprehensive examination of the wear mechanisms, wheel and rail, was undertaken, together with a de- tailed study of the dynamic interaction between the wheel and the rail. As part of this detailed study, a series of specific activity areas were defined, and each of these areas were ad- dressed both individually and as part of the overall integrated study. These specific study areas included the following: 1. Field investigation of rail and wheel wear. 2.Computer simulation of wheel/rail interaction and wear, 3.Analysis of wheel and rail profiles. 4.Analysis of rail grinding effects and requirements. 5.Evaluation of rail lubrication effectiveness. 6.Evaluation of track geometry (super-elevation and unbalance) effects. 7.Assessment of critical measurements and tolerances. 8.Economic benefit analysis. This paper presents a summary of each of these activities together with some of the overall finding and recommendations of this study. It should be noted here that this study was specific to the conditions and operations of the Railroad Division of SEPTA, and any extrapolation of these results to other properties should be done with extreme caution.
Controlling Track Forces during Introduction of New High Speed Trains
(International Railway Journal, 2001-10) Zarembski, Allan M.; Palese, J. W.; Bell, J. G.
As part of its program to introduce a new generation of high speed trains in the United States, Amtrak, the owner of both the equipment and the infrastructure, defined an objective of minimizing any increase in track maintenance or damage to the track structure or its components. The concrete ties on the Northeast Corridor were a particular source of concern in light of the tie cracking problems that had been experienced by Amtrak in the 1980s. The primary focus of attention was the dynamic wheel/rail impact forces applied to the track structure. Research studies have shown that significant increases in wheel/rail dynamic forces can occur at high speeds with a corresponding potential increase in track degradation, component failure, and track maintenance costs. To avoid this effect, Amtrak introduced a specific requirement for the design of the new high speed Northeast Corridor equipment to maintain the level of dynamic vertical wheel/rail forces applied to the track no higher than current levels. Thus for proposed new electric equipment to be operated at 150 mph, the dynamic impact forces were set at a level corresponding to the existing AEM7 electric locomotive operating at 125 mph. Likewise for the proposed new fossil fuel (diesel) equipment to be operated at 125 mph, the force levels were set to that of the existing F40 diesel locomotive operating at 90 mph.
Corrugation Behavior in the Freight Railroad Environment
(American Railway Engineering Association, 1987-10) Zarembski, Allan M.; Izbinsky, G.; Handal, S. N.; Worthington, W. M.
Rail corrugations are a phenomenon found on almost all types of railway systems throughout the world. Corrugations have been defined to be “rail head anomalies that appear on the surface of the rail in a repeatable manner along the length of the rail” (1). Though they appear as "waves" or regularly spaced discontinuities on the railhead, they are not always uniformly spaced, but tend to vary about an average (or, as shall be seen later in this paper, average range of) wavelength(s) (Figure 1). Corrugations are generally classed according to their range of wavelengths, which is the peak to peak (or valley to valley) distance between adjacent corrugations, as illustrated in Figure 1. The corresponding depth of the corrugation is the difference in height between the peak and valley of the wave. Corrugations can range in depth from .005 inch (where they are barely detectable) to .050 inch and greater (where there is no doubt whatsoever as to their presence), depending on the corrugation type and wavelength. Consequently, they can result in significant dynamic forces being applied to the rail and the rest of the track structure, as vehicular traffic moves over the site of the corrugations. However, in studying the phenomenon of corrugations it appears that rather than having simply one type of corrugations, there is a broad range of corrugations that vary in characteristics (depth and wavelength) with different conditions. This is particularly true in examining the differences in corrugations observed on heavy axle load freight railways, such as the North American freight railroads, and lighter axle load passenger and transit railways. Several authors (2,3) have suggested at least three types of corrugations corresponding to three different sets of railway conditions and operations. The first class is the very short wavelength class of corrugations, referred to as either "roaring rail (2) or "corrugations" (3), associated with light axle load passenger and transit (4) systems. These corrugations range in wavelength from 1 to 3 or 4 inches. The second class of corrugations is the "freight railroad" corrugations, most frequently associated with heavy axle freight operations. These have been referred to as "short wave corrugations" (2) or simply "short waves" (3) and have traditionally been associated with wavelengths of between 4 and 12 inches. However, as will be seen in this paper, the actual range of these corrugations is between 6 and 48 inches. The third class or corrugations, generally referred to as “long waves”, are associated with high speed types of operations. The actual range of characteristics of these wavelengths have been the subject of some debate (5), however, they have been associated with wavelength of 50inches and greater (3). In view or the significant differences in definition of the different classes of corrugations, and the need for a suitable identification of the type of corrugations found in the North American freight railroads, it was determined that a detailed examination of the characteristics of these freight railroad corrugations was required This paper presents the results of this examination of the characteristics or North American freight railroad corrugations. As noted above, this study addressed the wavelength band of corrugations most frequently found on the North American freight railroads. Specifically, this report will examine the general distribution of corrugation, both by wavelength, and by depths. The relationships between corrugations; found on five different freight railroads, the influence of track structure (wood ties vs. concrete) on the corrugations, and the effect of rail grinding on corrugation removal. In addition, it attempts to address the issue of the consequences of corrugation. i.e. the effect of corrugations on wheel rail dynamics. It must be noted here, that while these results represent a significant amount of effort, both in the collection of a large amount of data from five different railroads, and in the analysis of this data, the results presented in this paper represent the preliminary results of this study.
Critical facility accessibility and road criticality assessment considering flood-induced partial failure
(Sustainable and Resilient Infrastructure, 2022-11-25) Gangwal, Utkarsh; Siders, A. R.; Horney, Jennifer; Michael, Holly A.; Dong, Shangjia
This paper examines communities’ accessibility to critical facilities such as hospitals, emergency medical services, and emergency shelters when facing flooding. We use travel speed reduction to account for flood-induced partial road failure. A modified betweenness centrality metric is also introduced to calculate the criticality of roads for connecting communities to critical facilities. The proposed model and metric are applied to the Delaware road network under 100-year floods. This model highlights the severe critical facility access loss risk due to flood isolation of facilities. The mapped post-flooding accessibility suggests a significant travel time increase to critical facilities and reveals disparities among communities, especially for vulnerable groups such as long-term care facility residents. We also identified critical roads that are vital for post-flooding access to critical facilities. The results of this research can help inform targeted infrastructure investment decisions and hazard mitigation strategies that contribute to equitable community resilience enhancement.

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