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By Dominik Gächter, Wojciech Szczepinski, Jakub Bieszczad

Increased requirements for rail transport north of Oslo have forced Norwegian Authorities to invest in the development of double-track rail to decrease traveling time and increase the frequency of the rail service. Part of this development is Tangenvika Bridge which is built on the largest lake and drinking water reservoir in Norway (Mjøsa). Once completed, it will be the longest railway bridge in Norway. The foundation design consists of drilled and driven composite piles. All the works are performed on water and because of its depth, all piles are installed from floating container pontoons instead of jack-up barges. In order to meet the strict steel quality requirements of composite piles, all piles are welded on land in a controlled environment and then transferred onto the transfer pontoons on water. Close to shores, due to the local presence of sensitive soils and the risk of underwater landslides, a total of 78 drilled piles (1016mm) are executed using the reverse circulation method (RC). All piles are drilled 2m into bedrock using a fully integrated ring bit system. In the deepest parts of the lake, a total of 60 driven piles (1430mm) are installed using 350kJ hydrohammer. The bottom of the piles are finished with a closed-ended pile tip, which is the most popular driven pile tip in Norway. All drilled and driven piles are installed in single lengths of up to 85m and net weight of 102t at 1:5 inclination. The lifting process of the piles on the water provides significant challenges for which a combination of 400t crane, 2 transfer pontoons, and a tugboat is used to provide a safe execution method.

Oct 7, 2024

By Ramin Motamed, Reza Mohammadi

Finite element methods play a crucial role in analyzing dynamic responses within soil-foundation-structural systems during earthquakes. The validation of these models using seismic recordings is paramount for their application in the seismic design of foundations. This paper focuses on the refinement and validation of finite element models developed to study the response of drilled shafts at the Hayward-I580/238 bridge in California. The research methodology employs a two-step finite element modeling approach. In the initial phase, a free-field soil model of the site was developed in a two-dimensional model with OpenSees. Subsequently, a drilled shaft with an elastic section was modeled to investigate the response of the deep foundation to earthquake motions. However, acknowledging that these assumptions may not fully represent actual conditions, a three-dimensional free-field model of the bridge site was developed using OpenSees software in this study. Additionally, an inelastic section model for one of the bridge's drilled shaft was introduced to better capture the shaft's response under seismic forces. Given the relatively weak ground motions recorded by the accelerometers at the Hayward-I580/238 bridge, hypothetical earthquake scenarios were generated to depict the nonlinear response of the model. The available recorded motions were used to fit the target design spectrum at the Hayward-I580/238 bridge following AASHTO-2009. Subsequently, the shaft's reaction was analyzed under seismic forces, examining various parameters such as displacements and reaction forces. The results highlight the impact of the introduced modifications on the accuracy of the finite element models under both weak and strong earthquakes. In conclusion, the enhanced models not only contribute to monitoring drilled shaft behavior during seismic events but also establish a robust framework for future seismic designs of drilled shafts, showcasing the benefits of OpenSees in seismic design of deep foundations. Keywords: deep foundation, drilled shaft, OpenSees, soil-foundation interaction, seismic design

Oct 7, 2024

By Mark Wade

This presents an overview of the successful construction of a large diameter using trenchless technologies for renewal in Casper, a region with few large-scale projects. This project preserved and enhanced the City's aging wastewater infrastructure for an additional 100+ years. The pipeline, known as the North Platte Sanitary Sewer Interceptor (NPSSI) represents a nine-mile conveyance system that was initially constructed in four phases between 1980 and 1983 as part of a wastewater regionalization effort in the Casper metropolitan service area. The pipe material for the interceptor was unlined reinforced concrete pipe (RCP). Due to elevated levels of H2S within the pipeline, associated sulfuric acid formation became problematic along the entire interceptor alignment, causing serious deterioration of the NPSSI. The project team of CEPI, BlueWater, and Jacobs utilized a series of internal inspections and investigations of the entire interceptor over a three-year period to assess its condition and requirements for rehabilitation. This led to the first phase of strategic rehabilitation utilizing cured-in-place pipeline (CIPP) by Aegion/Insituform. Construction of the most critical portions of the NPSSI began in mid-2022 and was completed in early 2023. The project scope consisted of 7,600’ of 48-54” pipe rehabilitation along with numerous deep-bury point repairs, junction structures, river siphons, and inlet/outlet structures. Despite record cold winter weather and numerous site challenges encountered, Insituform Technologies delivered the project to the City of Casper with only a single time extension. The total cost of the project was below the original contracted amount, or $8.1M. The Casper NPSSI demonstrates who the successful renewal of a deteriorating wastewater interceptor within a stream-sensitive aquafer can be done using trenchless renewal in the best way possible. Added value was provided from the collaboration by all stakeholders, careful planning, and executing innovative technologies, to achieve an outcome beyond expectation.

Oct 7, 2024

By Tajebe Bezabih, Tonya Sanders Thach, David Sinkhonde, Samia Kirchner, Hunter James, Derrick Mirindi

With the increasing demand for wood driven by population growth and urbanization, this study explores the potential of three-layer particleboards reinforced with waste fibers as a sustainable and eco-friendly alternative in building material technology. It focuses on various waste fibers such as sisal, bagasse, leather shavings, and waste papers, assessing their impact on the structural properties of particleboards. The research thoroughly evaluates key mechanical properties such as the modulus of rupture (MOR) and modulus of elasticity (MOE), as well as essential physical properties like water absorption (WA) and thickness swelling (TS). This investigation delves into the innovative use of organic and natural bio-waste particulates as reinforcing agents in polymer composites, specifically examining their role in enhancing particleboard characteristics. A significant finding of this study is that the enhanced particleboards not only meet, but sometimes exceed, the minimum standards set by various international guidelines for general purposes. This indicates that it is feasible to replace traditional wood fibers with certain organic waste materials while maintaining or even improving the performance of conventional particleboards. This advancement is particularly relevant to the construction industry, as it suggests that these improved particleboards can be effectively used as sustainable structural materials. By utilizing waste fibers, it not only aligns with global sustainability goals but also provides a practical solution for waste management across multiple industries. Consequently, this research represents a significant step forward in the development of building materials that support eco-friendly construction practices and contribute to the circular economy.

Oct 7, 2024

By Francisco Humire

Contemporary design criteria for ground improvement supporting structures frequently specify a maximum post-liquefaction reconsolidation settlement value. Typically, those settlement values are evaluated using methods developed to represent free field conditions in the absence of ground improvement. Centrifuge and full-scale field tests have shown that arrays of dense gravel columns reinforce the ground leading to a reduction of post-liquefaction settlements relative to free field values. Therefore, free field settlement estimations that do not account for the vertical reinforcement effects provided by columnar ground improvements lead to conservative estimates of post-liquefaction settlements. Gingery (2019) proposed a constitutive model able to capture the development of post-liquefaction volumetric deformations and presented its implementation in a finite difference numerical model. The model proposed by Gingery (2019) has the advantage over more simplified approaches in that it more rigorously captures many of the physical processes including porewater pressure dissipation, gradual regain of soil stiffness and strength, downdrag, and stress redistribution. The objective of this work is to further validate the constitutive model proposed by Gingery (2019) and investigate the post-liquefaction settlement reduction due to vertical reinforcement effects for different subsurface profiles. This is done by (1) validating the constitutive model against more recent centrifuge and full-scale field tests, and (2) quantifying the post-liquefaction settlement reduction that is attributable to vertical reinforcement effects for different site conditions. Our simulations show a reduction of 15 to 20% of post-liquefaction settlements relative to free field values when considering vertical reinforcement effects.

Oct 7, 2024

By Joseph Seibold, Kavin Khatri, Siobhan O'Reilly-Shah, Neel Neelakantan

San Francisco’s New Headworks Facility Project consists of the design and construction of a state-of-the-art Headworks Facility designed to treat up to 250 million gallons of wastewater a day. The site is located in the Bayview District of San Francisco, California and is subject to various geohazards, including liquefiable artificial fill, compressible Bay Mud, multiple aquifers (including a pressurized aquifer), and high seismicity. To mitigate these hazards, and to accommodate the anticipated structural load demands, the New Headworks Facility structures were designed to be supported on large diameter drilled shafts. Bi-directional load tests (BDLTs) were designed and carried out to calibrate the analysis and confirm the design. During pre-production construction, two 36-inch-diameter drilled shafts approximately 125 feet long were installed at the project site. Each drilled shaft was instrumented with a bi-directional load cell, Linear Vibrating Wire Displacement Transducers, and eight strain gauges at select locations. The BDLTs were carried out after shaft installation. With careful consideration of the geotechnical conditions, the upward and downward displacement of the shaft segments above and below the bi-directional load cell mobilized at about the same time, allowing for significant data acquisition that resulted optimization for the foundation design. Through the successful implementation of a BDLT program, the drilled shaft lengths were able to be reduced significantly, resulting in substantial cost savings to the San Francisco Public Utilities Commission (SFPUC). This paper presents a discussion of the BLDT program performed for the New Headworks Facility Project, and how BDLT can be implemented as an effective method for estimating capacities on large-scale public infrastructure projects. Keywords: Bi-directional load testing, load cell, drilled shafts

Oct 7, 2024

By Scott Lakes

In recent years, Southeast Florida water agencies have been collaborating to develop a regional water supply that is sustainable and affordable. The C-51 drainage canal was selected as a leading candidate for the construction of a water reservoir – named the C-51 Reservoir – to store raw water for future use. The reservoir will capture storm water that is currently lost to the Lake Worth Lagoon estuary for storage. Phase One, recently completed, is estimated to store 14,000 acre-feet and supply 35 million gallons per day (MGD) of raw water to participating utilities. In addition to sustainable water storage and supply, the C-51 Reservoir Project will reduce excess freshwater discharges to the brackish Lake Worth Lagoon and improve water quality. The reservoir would also serve to assist with flood control and Everglades restoration efforts The reservoir design includes a cutoff wall that runs the entire length of the embankment’s axis. The cutoff wall largely consists of a minimum 2.5-foot-wide soil-bentonite (SB) wall with a small section of a soil-cement-bentonite (SCB) wall where twin 96-inch diameter conveyance pipes for the gated control structure cross the cutoff wall alignment. The total length of the cutoff wall is about 20,400 feet and extends through a limestone stratum into underlying sands with a total depth of about 50 feet. The cutoff wall ties into an RCC embankment. This paper provides the approach to construction, quality, and lessons learned from the cutoff wall construction. Details and issues with the cutoff wall tie in are described. Keywords: cutoff wall, soil-bentonite

Oct 7, 2024

By Charlotte Caton, Adam Dyer

Developing lands adjacent to environ­mental cleanup sites can come with a high construction cost. This is the case for many sites being developed around the highly contaminated Gowanus Canal, a Superfund site in Brooklyn, New York. One of the main challenges for construction near the Gowanus Canal is preventing contaminants from migrating into the sites and avoiding the cost associated with dewatering contaminated groundwater near the ground surface. Therefore, seldom are buildings around the canal designed to have a cellar. However, the unique development conditions at the 420 Carroll Street project site required a ceHar to be constructed in two buildings, 20 ft (6 m) below groundwater, with a tunnel connecting them, in a neighborhood where cellars below groundwater typically aren't built and where subsurface conditions are complex. The solution was a soil mix mass support of excavation system (SOE) with steel core beams for lateral support and drilled displacement piles for uplift resistance. A dry excavation up to 20 ft (6 m) below groundwater was accomplished at a distance of about 100 ft (30 m) from the canal.

Oct 1, 2024

By Junho Lee, Lin Huang, Alejandro Martinez, Charles Aubeny

Offshore wind farms are one of the principal sources of renewable energy worldwide due to their large potential for energy generation and remote locations. In the U.S., a number of offshore wind farms have been operating for several years on the East Coast, while two potential locations have been approved on the West Coast. While the shallower waters in the Atlantic Ocean allow for building wind turbines with fixed foundations like monopiles, the substantial water depths of the Pacific Ocean, which can exceed 1,000 m (3,280 ft), require the use of floating turbines with mooring systems. In fact, 65% of the U.S. offshore wind resources are located in deep water regions where water depth is greater than 60 m (197 ft). Since foundation systems typically account for 15-20% of the total construction cost of floating offshore wind turbines, optimizing the design can have a large impact on their cost competitiveness with respect to other sources like onshore wind and solar. A strategy that has received signifi­cant attention recently is to share anchors between floating wind turbines. This differs from the conventional configuration consisting of three nonshared anchors per turbine. The benefits of the shared anchor configur­ation are significant. For example, if every anchor in a wind farm is shared by three turbines, this reduces the number of required anchors by a factor of three. The capacity of offshore anchors depends on a number of factors including the loading inclination angle, embedment depth, soil properties and loading history. Of these, the former depends on the water depth, distance between turbines and mooring line configuration (i.e., taut versus catenary). This article focuses on assessing the effect of the loading angle on the monotonic capacity of ring anchors in sand.

Sep 1, 2024

By James Walters, Samuel Sideras, Kathryn Petek

The Oregon Department of Transporta­tion {ODOT} is currently performing a seismic retrofit and widening of the Abernethy Bridge as part the 1-205: Stafford Road to OR213 Improvements Project. The Abernethy Bridge, located in Clackamas County, conveys traffic over the Willamette River between the cities of West Linn and Oregon City. The existing bridge structure was completed in 1971 and is approximately 2,700 ft {820 m) in length and consists of 14 piers and two abutments, not including on­and off-ramp structures. At the bridge ocation, the Willamette River is approximately 1,050 ft {320 m) wide. The main channel crossing structure comprises three spans up to 450 ft (137m) long supported on Piers 3 through 6. The west approach structure includes nine continuous spans up to 195 ft {60 m) long and supported on Piers 6 through 14 and Abutment 2. The existing bridge piers are supported on a combination of driven steel H-piles and shallow foundations bearing on basalt bedrock. Construction of the bridge widening and seismic retrofit began in July 2022, which will add one lane in each direction and increase the width of the existing bridge from 100 ft (30 m) to 140 ft {43 m). The seismic retrofit will improve bridge performance to con­temporary seismic design standards and feature a two-level seismic design approach including both operational and life safety design and performance criteria. The foundation design for the project was driven by the highly variable geologic conditions across the project alignment, site constraints and the significant seismic demands. To meet the seismic performance criteria, the foundation solutions for the widening and seismic retrofit included micropiles, ground improvement and drilled shafts up to 12 ft (3.6 m) in diameter. This article describes the foundation design process and methodology and the foundation mitigation solutions developed for the project, as well as discussion of using 12 ft {3.6 m) diameter drilled shafts to mitigate the impacts of deep-seated permanent soil displacements.

Sep 1, 2024

By Jordan Romero, Jimmy Nettles, Daniel Sprunk

The Venture Global Plaquemines LNG Project in Port Sulphur, Louisiana, stands as a great achievement in the world of liquefied natural gas (LNG) infrastructure. Encompassing a 632 acre (255 ha) site, 20 miles (32 km) south of New Orleans along the Mississippi River, it's designed to be one of the largest LNG export facilities in the U.S., with the capacity to handle up to 20 million metric tons (22 T) of LNG per year. The project's scope includes multiple LNG trains, storage tanks and large marine terminal infrastructure. The construction involves significant civil works, including deep foundation and flood protection systems. Given the scale and complexity of the project, the construction process is highly intricate, involving a multitude of deep foundation disciplines and coordination among various contractors and stakeholders. Cajun Industries was tasked with several critical components of the piling and civil construction phase, including the development of hurricane protection systems and the execution of extensive deep foundation scopes through the life cycle of the project. This involvement in the project began with a small-scale precast concrete test pile program using just one pile driving rig in 2020. By May 2024, operations had expanded significantly, with a peak workforce of 200 employees, 30 piling rigs and 15 different piling scopes. These scopes included a design-build flood protection system for the project's laydown yard and construction support facilities, single-piece pipe piles up to 145 ft (44 m) long, precast concrete piles up to 120 ft (37 m) long, 41 cofferdams with sheet piles up to 80 ft (24 m) Jong, as well as 140 ft (43 m) long H-piles. The scope also encompassed a comprehensive test pile program featuring more than 150 load tests. Over the course of the project, the team executed more than 575,000 safe man-hours, installing 18,300 piles of various types and sizes. These efforts equated to the installation of more than 1,965,9001ft (600,000 m) of piling or 372 mi (600 km), weighing a staggering 312 million lb (142 million kg). For perspective, one could travel three round trips to outer space when comparing the linear footage of piling.

Sep 1, 2024

By Alan Walka, Paul Deterling

The existing B and D wings of the Somerville High School in Somerville, Massachusetts, were required to be underpinned to allow for additions to and a large expansion of this facility. A combination of micropiles and soil nailing was designed by Earthwork Engineering and Hub to provide both structural underpinning of the existing foundations and lateral support for both the structures and the soils below the foundations. The depth of the exca­vation was up to 25 ft (8 m) below the existing foundations.

Sep 1, 2024

By Ryan Nagle, Eric Lindquist, Rob Jameson, Kelli Mccurdy, John Gouchon, Serena Jang

The 200 Park Avenue project is located in the San Francisco Bay Area in the Santa Clara Valley. The Santa Clara Valley is situated at the base of two mountain ranges consisting of the Santa Cruz Mountains on the west and the Diablo Range on the east. More specifically, the project is in downtown San Jose, which was formerly utilized for agricultural production until the technology industry rapidly grew in the 20th century. As a result, downtown San Jose quickly transitioned into a metropolitan area. The project site is located within a portion of a downtown city block and has maximum plan dimensions of about 270 by 220 ft {83 by 67 m) and encompasses about 1.7 acres (0.7 ha). Prior to construction, the site was occupied by an at-grade office building, a parking garage with partial basement and a paved parking lot. The development has recently been completed and comprises a 19-story office tower with four levels of below­grade parking. The basement construc­tion required a 54-58 ft {16-18 m) deep excavation that occupies the entire footprint of the site. The shoring system installation began in December 2019 and mass excavation was completed in September 2020. The construction of the office tower was completed during the summer of 2022.

Jul 1, 2024

By Erich Steinlechner, Freddy Lopez

The Rhine, with its length of approx­imately 1,230 km (764 mi), is the second-longest river in Central and Western Europe and one of the most important navigable waterways in the world. The alpine Rhine (or Alpenrhein) is the section of the river between Reichenau, Switzerland, and the Rhine's confluence with Lake Con­stance on the borders of Germany, Austria and Switzerland. A Swiss­Austrian flood control project known locally as RHESI aims to protect the habitat of about 300,000 people living in the valley along the "international stream" of the alpine Rhine. Along the international stream, the Rhine flows within a central channel toward Lake Constance in a canal-type bed with fortified embankments. In the event of rising water levels, the Rhine floods the foreland, stressing the existing flood embankments (dams). In order to allow even larger amounts of water to flow off safely, more space and new (or rehabilitated) dams are re- quired. With the implementation of the RHESI project, the middle channel of the Rhine will be significantly widened, and the foreland reduced, creating more space for the river. Around 65% of the flood embankments will be rehabili- tated and 25% completely renewed, while 10% of the dams will remain as they are today. These measures will increase the discharge capacity from the current 100-year to a 300-year flood rate. More discharge capacity means better protection against flood events.

Jul 1, 2024

By Basha Qubain, Kamil Nuzha, Jianchao Li

This article pertains to a 52-story residential high-rise building in the Rittenhouse Square section of Philadelphia, a densely developed area with mixed residential and commercial buildings. The tower is surrounded by Moravian Street along the north, Walnut Street to the south, a residential building to the east and a three-story historic building to the west. It measures 40 m (130 ft) long by 22.8 m (75 ft) wide with a finished floor elevation of 12 m (40 ft) and a full basement at elevation 7.5 m (24.5 ft). The historic building has a finished floor elevation of 13.7 m (45 ft) and its basement at elevation 10. 7 m (35.3 ft). It is supported on a 0.5 m (1.5 ft) thick rubble wall with a bottom at elevation 10.6 m (35.0 ft). The tower mat extends 36 ft (11 m) below grade or about 28 ft (8.S) below the existing historic build­ing, thereby requiring underpinning. When fully loaded, the settlement of the mat will cause the abut ting underpinning to also setUe, which would be detrimental to the historic building. Therefore, an innovative solution was necessary to isolate the underpinning from the stresses induced by the adjacent mat to safeguard the historic structure.

Jul 1, 2024

By Dov Leshchinsky

Mechanically stabilized earth (MSE) walls are composed of three main elements: soil, reinforcement and a facing. If any of these elements are not functioning, its internal performance would be unacceptable. In extreme cases, it will result in a collapse. How­ever, if material characterization, design and construction are properly done, MSE walls will exhibit excellent long-term performance while being economical. In fact, when using multiple reinforce­ments, redundancy is rendered, i.e., 'overstressing' loads can be alleviated by shedding it to understressed layers. Common design of MSE walls with respect to reinforcement and facing is generally conservative. However, soil is often poorly characterized. The result is either an overly conservative structure or worse, unacceptable structural per­formance. Underestimation of backfill strength is typical as often default shear strength is used. For example, the American Association of State Highway and Transportation Officials (AASHTO) specifies select reinforced soil, sug­gesting a default friction angle of q>=34° with an upper limit of 40°. For the select backfill specified in AASHTO, this angle is likely to be 45-55° implying that the actual strength of the compacted backfill could be as much as 50% larger. However, if in construction the rein­forced soil is poorly compacted or drained, conservatism due to underes­timated soil strength may vanish, potentially leading to poor wall per­formance. This is not different from other geotechnical structures. The objective of this article is to report failures of two dissimilar walls, ending with costly remediations that changed the characteristics of original MSE structures. The cases reported are not unusual and reflect similar prob­lems in other MSE wall failures the author has investigated. The reported cases are based on forensic studies and, in a general sense, are structured as such: A known outcome, e.g., excessive settlement or collapse. An investigation process to separate the chaff from the wheat, i.e., distin­guish between the "noise" typically promoted by lawyers who are ad­vocating for a client.

Jul 1, 2024

By Alan Walka, Paul Deterling

Nestled among the lovely 19th century Greek revival, Queen Anne and Italianate architecture, Somerville High School sits atop the Spring Hill in Somerville, Massachusetts. Originally constructed in 1872, the high school has experienced several major renovations and This is the first in a additions throughout it 147-year history. Citing inefficient heating and cooling systems, inadequate access, structural repairs to its exterior, and that all major building systems were at the end of their useful life, the Massa­chusetts School Building Authority approved a feas­ibility study for construction and renovation and city residents voted overwhelmingly to fund the estimated $256 million project, making it the most expensive high school construction project in Massa­chusetts' history.

Jul 1, 2024

By Andrew Moran

In 2021, the University of Pittsburgh began construction of a new recreation and wellness center for students and faculty in the heart of its main campus in Pittsburgh. The design and plans for the center promote the university's goals to create a unique place for members to stay active and to sustainably develop the area within its urban campus. The new 270,000 sq ft (25,000 sq m) center is being constructed within the footprint of two former campus buildings that were demolished, the O'Hara Parking Plaza and the Learning Research and Development Center (LRDC). The recreation center borders O'Hara Street on its south side, the ramp to receiving for the Western Psychiatric Hospital (WPIC) on the west side, an internal campus service road called University Drive A on the north side and a long thin area that will become a new terraced pathway on the east side. The existing site grade ranges from elevation 965-1,058 ft (294-323 m) within the area of the proposed recre­ation center. The ground surface at the site slopes between O'Hara Street in the south upward to the service road in the north with a grade difference of approx­imately 100 ft (30.5 m). The bottom of the excavation for the new center will be near the lowest elevation of O'Hara Street, requiring support of excavation (SOE) on the north (LRDC and O'Hara walls) and west (WPIC wall) sides. Mascaro Construction Company, the general contractor, engaged Nicholson Construction Company for the first stage of the construction, which included existing building demolition, earthwork and SOE systems. Nicholson designed and constructed the SOE systems along the site's north and west sides as described.

Jun 1, 2024

By Rebecca Hurley

Spring in the state of Kentucky brings every climate possible within a matter of weeks. Typically, the initial thaw from winter occurs followed by flash flooding rain. The heat is kicked up for a few random days just for the semi-dried soil to be washed away by another torrent of rainfall. Judging by the last few years, a round of tornadoes can also be expected to make an appearance. Haunting fog will plague the hollers in the evening, veiling the missing roadway washed away earlier that day. This creates an interesting obstacle course of dodging cliffs, cones, cars and the occasional ATV. Of course, a threat is posed to all the residents and travelers of the failed roadways. These rural area do not have the luxury of multiple access roads to their homes. Roads with a major failure preventing even a single line of traffic to pass through are deemed emergency projects and are prioritized to begin construction. This sequence of events took place in the early part of 2023 on a rural road in Harlan County, Kentucky, and this case study describes the processes and methods that allowed rapid response for reconstruction of the failed roadways.

Jun 1, 2024

By Brendan Stepek, Michael Senior, Gary Brill

Freight railroads are classified as critical infrastructure and are an important piece of the U.S. economy. Railroad tracks cover the entire nation, allowing freight trains to transport goods and materials between ports and other transportation hubs. We have shaped the landscape to construct America's vast network of railroads; we have flattened mountains, carved into hillsides, filled valleys and spanned gorges. As natural geotechnical hazards occur at railroad sites, it is critical to remediate the hazard in a timely and minimally disruptive manner to main­tain operations. Norfolk Southern Railway has mainline rail passing through the foothills of the Blue Ridge Mountains of Central Virginia that services about 15 to 20 trains per day. Along this rail is a 70 ft (21 m) high cross valley embankment fill that has experienced a long history of instability and numerous attempted repairs. In 2020, after a noticeable increase in rail movement, Norfolk Southern elected to have a compre­hensive geotechnical study of the embankment performed, install instru­mentation and ultimately stabilize the soil slope. The instrumentation and design of the slope stabilization system was performed by Schnabel in 2021 and was constructed by Goettle in 2022.

May 1, 2024