Design-Build Devore Interchange a Caltrans First in Inland EmpireReduced risk, high quality and fast & reliable

REConews

Location: San Bernardino County, CAThree Interstate highways, I-10, I-15 and I-40, enter southern California from Arizona and Nevada, carrying traffic to and from greater Los Angeles. I-40 ends in Barstow, joining I-15 which winds its way through the Cajon Pass and traverses the “Inland Empire”, the Riverside-San Bernardino-Ontario metropolitan area directly east of LA and the 13th-most populous metropolitan area in the United States. Drivers traveling in or out of Southern California must not only navigate the congested environs of the Inland Empire, but they must also pass through the Devore Interchange, where I-15 and I-215 meet in the City and County of San Bernardino.Severe delays are commonplace, with 5-mile backups typical during peak afternoon and weekend hours, as more than 1,000,000 vehicles squeeze through the Devore Interchange every week. This

includes 21,000 trucks daily, part of a massive movement of freight into and out of Southern California through this nationally significant primary goods movement corridor. The interchange is also a major route to recreation destinations such as Las Vegas and the Colorado River. Therefore, the goal of the $324 million Devore Interchange Project is reduction of congestion and accidents, while providing significant improvement of freeway operation.A highway design-build (DB) pilot program was authorized by the California legislature in 2009 and the California Department of Transportation (Caltrans) selected Devore as one of 15 projects to test this project delivery system. Seeking relief from the paralyzing dysfunction at the intersection of I-15 and I-215, Caltrans sought the same advantages realized by other states on hundreds of DB projects:

In this Issue

Cover Story:

Devore Interchange .................................... .1

Upcoming Events ........................................ 3

Broad Street Parkway ................................ 4

La Villita MSE Walls .................................. 6

Noteworthy Projects ................................. 8

Winter 2016

REINFORCED EARTH®

www.reinforcedearth.comContactUs@reinforcedearth.com

1.800.446.5700

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• Better Quality – design-builders meet performance standards, not simply minimum design requirements. DB encourages innovations, can produce better project results than originally planned.• Faster Delivery – collaborative project management speeds completion, with fewer problems.• Cost Savings – designers and constructors are an integrated team; efficiency and innovation can extract the most value from public dollars.• Singular Responsibility – one entity is accountable for cost, schedule and performance.• Reduced Risk – the design-build team assumes additional risk, compared to design-bid-build method.• Decreased Administrative Burden – owners can focus on the overall project rather than managing disparate contracts.Awarded to Atkinson Construction (Irvine) in 2012 for scheduled completion in 2016, the $208 million construction contract adds one lane in each direction, builds 18 bridges, adds a truck bypass lane in each direction to eliminate weaving and improve overall safety, and reconnects Cajon Boulevard, the alignment of Historic Route 66 that was severed by the original interchange construction in the 1970s. Atkinson’s design called for 10 mechanically stabilized earth (MSE) walls totaling nearly 128,000 sq. ft., some of which face Cajon/Route 66 and required

a high quality and visually appealing aesthetic treatment. This requirement was met by using a “New England Dry Stack” simulated stone facing panel finish, punctuated on longer walls by intermittent columns of smooth, raised finish panels (Fig. 1).Based on previous successful Southern California project partnerships with The Reinforced Earth Company (RECo), Atkinson asked RECo to design and supply Reinforced Earth® MSE walls for the Devore Interchange. By doing so, Atkinson helped Caltrans achieve the advantages it sought from using design-build:• Better Quality – RECo specializes in working as part of a DB team to provide customized designs that innovatively meet project engineering and productivity requirements. While anyone can design a wall that is long enough, high enough and has enough soil reinforcements, RECo’s designers work hand-in-hand with the DB contractor to develop designs that also optimize constructability while minimizing the cost of construction. Steeply stepped foundations (Fig. 2) require careful work at first, but pay off quickly through reduced excavation, less buried wall, and by allowing the contractor to rapidly achieve a longer, more productive stretch of wall to work on. And the square-shape Reinforced Earth facing panels were cast on a form liner, assuring a high quality finish and visual consistency from wall to wall.

• Faster Delivery – the in-house designers and project managers at RECo control every aspect of MSE wall design, fabrication and delivery, allowing seamless flow of approved designs directly into production of reinforcements and facing panels. RECo’s long-time precaster, Harper Precast, had extensive experience with Reinforced Earth products, assuring timely and trouble-free production. Though located in Salt Lake City, Harper’s 637-mile delivery distance was only a one-day straight shot down I-15 right to the jobsite. • Cost Savings – on a design-build project time is money, and Atkinson’s design optimization process saved both. Using Reinforced Earth retaining walls helped achieve a 10% reduction in earthwork cuts and eliminated several embankment slopes, saving construction time and dollars. Onsite backfill was suitable for MSE wall construction, eliminating the cost to acquire and deliver imported borrow. And the speed of Reinforced Earth wall construction helped shorten the project schedule. In addition, both monetary and social costs were reduced by the extensive use of MSE walls, which contributed to reducing acquired right-of-way by 12 acres and 8 private residences.• Singular Responsibility – according to Caltrans, “singular responsibility” in DB means one entity is accountable for cost, schedule and performance. That exactly describes The Reinforced Earth Company, which was solely responsible to design, manufacture and timely

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Figure 1. Reinforced Earth walls with New England Dry Stack facing panels

deliver its MSE walls on the schedule set forth by Atkinson Construction. RECo even provides its own project manager to help the contractor learn the best Reinforced Earth construction procedures applicable to the project. • Reduced Risk – while the design-build team assumes additional risk compared to the design-bid-build method, the team also has complete control of that risk. RECo’s singular responsibility for MSE wall design and proven performance record of timely delivery and knowledgeable field service actually reduced the DB team’s risk.Reduced risk, high quality, fast and reliable delivery and lower cost – and all from a single entity experienced in being responsible to accomplish it all. That’s what Atkinson Construction was looking for when they partnered with The Reinforced Earth Company and, as this story is being written, Atkinson is getting what they asked for. With Reinforced Earth wall construction nearing completion, and overall project completion just around the corner, drivers move ever closer to realizing the benefits of Caltrans’ design-build pilot program: smoother and faster traffic flow in the upgraded and beautified Devore Interchange in Southern California’s Inland Empire. Figure 2. Productivity increases rapidly as steeply stepped foundations get contractors out quickly

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Upcoming EventsTRBJanuary 10-12, 2016 Washington, DC

FTBAFebruary 9-10, 2016Orlando, FL

ASCE GeoTechFebruary 14-17, 2016 Phoenix, AZ

SMEFebruary 21-24, 2016Englewood, CO

T.H.E. ConferenceFebruary 23-24, 2016Urbana-Champaign, IL

Western MiningMarch 21-24, 2016Denver, CO

Location: Nashua, NH

Like main roads in many cities and towns, Broad Street in Nashua, New Hampshire begins in the western suburbs and extends to the westerly edge of the downtown district. Along the way it intersects the F.E. Everett Turnpike (US Rte. 3), a heavily-traveled toll highway running from the Massachusetts border and Boston, to the south, to Concord, the state capital to the north. The combination of suburban and interchange traffic between the Turnpike and downtown causes congestion, increases pollution in Nashua’s Central Business District, and impacts public safety by reducing mobility of emergency vehicles. The recently completed “fix” is the Broad Street Parkway, the largest municipally-managed public works project in New Hampshire. Part of a long-term transportation strategy to improve air quality conditions in Nashua, construction of Broad Street Parkway also provides an economic benefit by enabling redevelopment in a long underutilized section of the city.

There was only one possible alignment for the Parkway as it departs its starting point at Broad Street and heads for downtown: through a narrow space between the adjacent railroad and an oxbow in the Nashua River, flowing more than 50 ft. below. Based on New Hampshire DOT (NHDOT) design standards, project plans prepared by Fay, Spofford & Thorndike, LLC (FST), of Bedford, NH, called for a Mechanically Stabilized Earth (MSE) retaining wall to handle the grade differential and a sheet pile wall (“cofferdam”), located behind the MSE wall, to support the excavation and the railroad. Addressing the railroad’s self-protection requirements while keeping the MSE wall and sheet pile wall sufficiently back from the river was a complex task, made more difficult by concerns for global stability of the overall hillside. FST specified the required wall systems, but left it to the contractor to design those wall systems and address the global stability challenge.

R.S. Audley, Inc., of Bow, NH, the project’s general contractor, had a plan. It began with asking The Reinforced Earth Company (RECo) to supply a Reinforced Earth® retaining wall for the MSE structure, because Audley knew they could rely on RECo for a quality-engineered product, a timely response and responsive local field service. The contractor’s plan also included moving the sheet pile wall farther away from the railroad, not only to minimize the influence of railroad loading but also to prevent the anchors of the sheet pile wall from extending under the railroad. So Audley worked closely with RECo Vice President and Regional Manager Peter L. Anderson, P.E., to optimize the combination of the two earth retention systems – the tied-back sheet pile excavation support to protect the railroad and the MSE wall to carry the Parkway between the railroad and the river.

In a typical Reinforced Earth wall design, the reinforcing strip length is 70% of the design height of the structure from top to bottom of wall. For the central portion of the Broad Street Parkway wall, the 70% length is 32 ft. But to address anticipated global stability issues on this project, FST required the soil reinforcements to be 100% of the design height where the MSE wall was taller than 30 ft. – meaning 45 ft. strips were needed. However, relocating the excavation support further away from the railroad left only 23 ft. for the reinforcing strips in the central portion of the wall, instead of the typical design length of 32 ft., and far less than the 45 ft. strips mandated by the “100% of design height” requirement.

S. W. Cole Engineering (Manchester, NH), was the project geotechnical consultant. Cole’s analysis indicated that the sheet piles needed to be driven significantly deeper than had been planned, to intersect deep slip circles and satisfy global stability of the hillside above the river. As a permanent structure, the sheet piles had to be designed for a 100-year design ife,

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Figure 1. Trapezoidal cross section of Reinforced Earth Wall

Broad Street ParkwayLargest Municipally-managed Public Works Project in NH

leading to extra thick sheeting sections to provide sacrificial thickness and assure adequate section remaining after 100 years. As designed and installed by specialty foundation contractor H. B. Fleming, Inc. (South Portland, ME), this relocated, anchored, deep-seated, extra thick stabilizing structure significantly changed the design parameters for the Reinforced Earth wall.

The excavation support system satisfied global stability requirements, eliminating the “100% of design height” strip length requirement and reducing the lateral earth pressure at the bottom of the MSE wall. With reduced lateral earth pressure, overturning and sliding could be satisfied using the 23 ft. base width available in front of the sheeting. Since the sheeting rose less than half the Reinforced Earth wall height, RECo designers used normal 70% design length (32 ft.) reinforcing strips above the sheeting, creating what is called a trapezoidal section (Fig. 1).

The additional internal load imposed on the MSE structure, including a potential 100-year design flood, was handled by increasing the number of reinforcing strips at the bottom of the wall, while the free-draining crushed stone backfill minimized the development of an unbalanced head during drawdown after a flood. Other design details specified by NHDOT included an impervious membrane and perforated collector pipe above the reinforced backfill, and a “rail support slab” atop and overhanging the wall to support a bridge railing.

Construction of this 495 ft. long, nearly 16,000 sq. ft. retaining wall required working from the base of a deep hillside excavation, with steep access grades to be negotiated by equipment and personnel. Sandwiched between the river in front of the wall and the sheet pile wall behind it (Fig. 2), working space was limited. But the contractor used the knowledge gained building Reinforced Earth walls on previous projects, coupled with dependable facing panel deliveries from precaster Dailey Precast LLC (Shaftsbury, VT) and the easily placed and compacted backfill, to produce a well-constructed, good looking wall. When asked what he considered special about this wall they had built, R.S. Audley’s Vice President and Project Manager, Scott Stevens, proudly

answered, “the immense height, length and curvature of the wall, along with the innovative cofferdam [excavation support wall] – that should cover it.”

The coarsely-textured ashlar stone surfaces of the cruciform-shape facing panels (Fig. 3) give the Broad Street Parkway retaining wall a pleasing appearance, consistent with New Hampshire’s nickname, “The Granite State.” And completion of the project gives Nashua’s citizens a new route into their city. Yet as people travel the Broad Street Parkway, high above the Nashua River, few will realize the complex engineering or the challenging planning and construction that went into the Reinforced Earth wall supporting them on their journey.

Figure 3. Ashlar stone panel finish blends well into it’s surroundings

Figure 2. Reinforced Earth Wall adjacent to flood-prone Nashua River

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MSE Walls Become the Central Aesthetic Feature at La Villita Apartments & Homes Suporting a Variety of Loading Conditions

Figure 1. Rusticated, stucco-textured top panels above normal water elevation

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Location: Irving, TX

Responding to specialized customer needs with beauty, performance, service life and economy – that perfectly describes Reinforced Earth® custom-engineered Mechanically Stabilized Earth (MSE) retaining walls from The Reinforced Earth Company (RECo). But sometimes the architecture drives the project and the engineering must follow. That was exactly what Cousins Properties, Inc., manager for land owner Las Colinas Land Limited Partnership, found as it began developing the La Villita luxury apartments and homes, in Irving, TX. And Cousins Properties’ customers indirectly drove the aesthetic design of La Villita through their expectation of an architectural character that would be commensurate with luxury living in Las Colinas.

Project consultant Carter & Burgess (Ft. Worth, now part of Jacobs Engineering Group, Inc.) needed to create an appropriate aesthetic feature, meaning La Villita homes and apartments would surround a lake and meandering waterways. The homes had to be protected from both the normal water level and periodic flooding of the lake and waterways, which ultimately flow into the Elm Fork of the Trinity River, requiring

installation of retaining walls along the waterways. These walls became central aesthetic features of the community, creating the need for a low key but distinctive look, while also offering reliable performance, long service life and, of course, initial economy.

In addressing the aesthetic concept created by Carter & Burgess’ in-house landscape architects, RECo identified an existing nearby highway project having an appearance similar to and adaptable to what was desired. The Dallas Central Expressway featured more than 2 million sq. ft. of wide rectangular facing panels set off by tall, narrow facing panels, giving the appearance of pilasters separating sections of the walls. Adapting this concept to La Villita, RECo designed walls typically 13 ft. tall, comprising two stacked rectangular facing panels, topped by precast coping and arranged in 4 panel wide (60 lf.) bays, with narrow pilaster panels delineating the bays.

The lower panels had smooth faces, while upper panels had a central rectangular inset where the concrete surface had a stucco form liner finish, adding to the distinctive appearance of the completed walls and the La Villita community (Fig. 1).

While the geotechnical design requirements were established by Rone Engineering (Dallas) the scope of RECo’s design included the analysis of a variety of loading conditions. Although the pedestrian promenade along the walls

imposed little load, the MSE design was required to consider the influence of building surcharge loading which began 26 feet back from the wall face. The walls also had to be designed for three different conditions related to the waterways – dry during construction (Fig. 2), saturated at normal pool conditions (water at mid-height of the wall), and 100-year flood, with water within 1 ft. of the top of wall. The design also had to address a 3 ft. drawdown condition, in which the water level in front of the wall is assumed to be 3 feet below the backfill saturation level, producing an unbalanced hydrostatic head. This saturation/drawdown condition was evaluated at all elevations below the 100 year flood level to ensure wall stability under all conditions.

The addition of hydrostatic pressure to the design reduces both the pullout safety factor of the soil reinforcements and the sliding safety factor of the MSE structure. Responding to both insufficient pullout resistance and insufficient sliding resistance, the reinforcement length of the La Villita Reinforced Earth walls was increased. As a result, reinforcing strip length in the compacted granular backfill behind the walls was generally 13 ft., equal to 100% of the design height (“100% aspect ratio”), as compared to the “standard design” 70% aspect ratio in structures not subject to flooding.

Both facing and pilaster panels had standard Reinforced Earth tie strips cast into their back faces and bolted to the Reinforced Earth high adherence ribbed reinforcing strips. A woven filter cloth covered all panel and pilaster joints on the

backfill side, to prevent escape of backfill during post-flood drainage, and a pedestrian railing was attached to the coping and supported by a cast-in-place moment slab. As part of the overall aesthetic character of the community, a number of planting wells were located approximately 10 ft. behind the wall. Not only did Carter & Burgess specify a commercial root barrier system to a depth of 3 feet to contain the plantable soil and prevent root intrusion through the wall facings, but they also specified a supplemental lateral force on the walls as a result of this root system. To accommodate the plantings, RECo designed the upper reinforcing strips to be gradually deflected downward to go below the planting wells.

Construction of the La Villita Reinforced Earth walls was closely linked to overall construction of the project’s water features, which began as a natural channel and a small pond. Recognizing

the aesthetic appeal of water near residences, the owner enlarged and deepened the pond to become an 85 ft. deep lake, with a flow control weir system at its downstream outlet. Initial filling of the lake was to a point 5 ft. below the Reinforced Earth walls, allowing construction in the dry. Upon successful completion of wall erection by Coppel Construction Co., the flow control weir structure was used to

raise the water level in the lake and canal by 10 ft., to the mid-height of the walls (normal pool).

The La Villita project required a very special architectural look as an integral part of the value of the property. At the same time, Cousins Properties sought to build the project at the lowest cost consistent with that aesthetic character. Reinforced Earth walls, well-known for their structural capabilities and cost effectiveness, would not normally have been considered to produce the look required at La Villita but, due to RECo’s imagination and “we will figure out a way” spirit, they were both considered and utilized. Though many special architectural challenges and design considerations had to be addressed, the result was a positive experience and an end product in which everyone takes pride. The engineering sophistication, long-term performance and initial economy of the Reinforced Earth walls may not be evident to the residents of La Villita, but they cannot miss the beauty of their own neighborhood Reinforced Earth walls.

Figure 2. Water level maintained 5 ft. below Reinforced Earth walls allowed construction in the dry.

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Noteworthy Projects

Portland to Milwaukee LRT Reinforced Earth® Full Height 2-Stage

Location: Portland, OR

Owner: Tri-Met

Contractor: Stacy & Witbeck, Inc.

Engineer: David Evans & Assoc. Inc.

York County Rail Trail Northern ExtensionReinforced Earth®

Location: Manchester, PA

Owner: PennDOT

Contractor: Kinsley Construction

Engineer: C.S. Davidson, Inc.

Vulcan Dreyfuss Quarry Reinforced Earth ®

Location: Columbia, SC

Owner: Vulcan Materials

Contractor: Sanitary Plumbing Contractors, Inc.

Engineer: Vulcan Materials

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