The City of Sugar Land, Texas, was named for the 150-year-old Imperial Sugar Company that is headquartered in the city. This company built the foundation of what is known today as Sugar Land and has influenced the culture of the city. While the headquarters is still located in Sugar Land, the refinery closed in 2003. Since the refinery has long been an integral part of the community, the city and its developers have made it a priority to preserve, enhance, and bring economic development to the area, now known as the Imperial District.
Providing new connectivity is essential to spurring growth in this area. University Boulevard provides access from US 90A into the heart of the Imperial District and to one of the city’s biggest attractions, Constellation Field. In addition, University Boulevard is a major north-south connector through the city that provides relief to the congested State Highway 6.
To further improve mobility to this district, the city is currently constructing the University Boulevard North Extension, a $21 million, 0.5-mile, four-lane, divided connector between US 90A and South Stadium Drive in front of Constellation Field. The road is adjacent to Nalco Champion and crosses Oyster Creek and Union Pacific Railroad (UPRR) tracks in two locations. The project includes reconstruction of a portion of US 90A, track work with UPRR, an at-grade rail crossing with traffic signal preemption near US 90A, a grade-separated overpass over a UPRR spur and Oyster Creek, a side path and sidewalk, retaining walls, and a bridge-supported water line.
With this extension, new opportunities are available to developers. “The property to the west (of University Blvd) was really not looked at by the developer as being really worth a whole lot until the agreement with UP came about and the extension project started,” said Chris Steubing, P.E., city engineer with the City of Sugar Land. “Now they have a valuable 16 acres of land that they have been able to put on the market and, from the city’s perspective, will be able to draw increased revenues.”
Lockwood, Andrews & Newnam, Inc. (LAN), a national civil engineering firm, is the project’s engineer-of-record. Harper Brothers is constructing the road and bridge portions of the project with construction anticipated to be complete in February 2018. Webber completed construction of the rail portion of the project in February 2017.
From developer to city council, this project was under intense focus and required significant stakeholder coordination to achieve success. Coordination was required with UPRR, Texas Department of Transportation (TxDOT), Nalco Champion, Johnson Development, and various smaller entities.
An agreement was made with UPRR prior to project development. In this agreement, UPRR would gain the easements needed for a new double-track along US 90A and close two crossings while developing a new crossing for University Boulevard. Typically, UPRR requires closing three crossings when opening a new crossing, so this agreement proved to be a pivotal success factor that was mutually beneficial to the city and UPRR.
One of the UPRR crossings that was closed was a private drive into Nalco Champion. To accommodate this loss, the city entered into an agreement with Nalco to locate two driveways on University Boulevard into their new headquarters adjacent to the project.
The UPRR tracks were 60 feet from and 3 feet higher than the edge of US 90A. Since US 90A was built with a standard crown cross-slope, there would be a bump in the road travelling over the tracks unless a major portion of US 90A was reconstructed. Coordination with TxDOT for modifications to US 90A, a major thoroughfare through the city that carries more than 60,000 cars daily, allowed more than 800 feet of US 90A to be reconstructed to reverse the slope of the roadway and provide a smooth ride over the UPRR tracks.
Finally, Johnson Development, the developer of the Imperial District, was committed to working with the city to provide connectivity to the Imperial District and ensure the overall vision of the district was present in the aesthetics of the project. To this end, Johnson was a major funding partner in the project and was consulted on all discussions of project aesthetics.
With all of the stakeholder agreements and coordination, the city expected this project to take as long as 10 years to complete. Due to hard work from city staff and the design team, as well as collaboration with each of the stakeholders, the project is anticipated to be completed within five years.
“It was a large collaboration and coordination project between several different parties,” said Steubing. “It’s the most expensive stretch of road that I think I’ve ever been a part of, but it’s going to be a great asset to the city when it’s done.”
The city’s proximity to the Gulf Coast influences geotechnical parameters at the site. The very soft, loose, sandy and silty soils with little to no bearing capacity and high settlement potential makes any civil project complicated. As such, the soils require a robust foundation for the rail, road, and even drainage elements.
Most notable was the soil’s effect on the bridge and retaining wall foundations. The flat terrain and vertical clearance required over the UPRR spur (23 feet, 4 inches) required embankments as tall as 23 feet. If founded on the in situ soils, the embankment would experience as much as 5 inches of settlement over time, causing significant maintenance issues for the city. To mitigate this, two foundation improvement options were evaluated: Remove and replace soil with cement-stabilized sand or use rigid inclusions.
While the cement-stabilized sand option would be the most cost effective, it did not fully mitigate the settlement potential of the embankment and required preloading of the structure, which would delay construction of the project. The rigid inclusion option involved placing a grid of small-diameter grout columns throughout the embankment area. This foundation improvement option penetrates the entire depth of low bearing capacity soils and minimizes long-term settlement of the embankment. To preserve its investment in this structure, the city opted for the rigid inclusions despite the higher cost.
Aesthetics for this project were a high priority for the client. The vision of the Imperial Redevelopment District featured an aesthetic scheme influenced by the historic Imperial Sugar Plant’s building architecture. The dominant aesthetic features included a dark, earth-tone brick veneer accented with pale precast stone trim elements. These features were most prominent on the exterior bridge and retaining wall columns that were clad with the brick veneer and extended above the deck as pilasters and included lighting features above.
One of the primary challenges with the aesthetics was detailing the precast stone trim elements. The bridge columns were inset into the bridge deck, allowing the pedestrian rails to terminate into the face of the columns at the ends of each span. To accommodate this scenario, special attention was given to the precise dimensions of the trim elements that wrapped around the columns.
A 3D model of the precast stone trim around the columns and along the deck was developed to visualize how each piece would fit together. Furthermore, the deck plans required block-out details to accommodate the column inset. Special consideration was given to ensure the precast stone trim elements wrapping around the columns were isolated from the bridge deck so that the bridge deck could thermally expand and contract without cracking the precast stone trim.
Another challenge with the aesthetics was accommodating the pedestrian rail posts that required anchorage to the bridge deck. To provide the contractor with more flexibility for installation, LAN detailed the rail posts’ anchorage so that the base plates could be post-installed instead of cast-in with the concrete deck. The precast stone trim complicated these details because rail posts had to extend through the trim pieces. Block-outs in the precast stone trim were provided so that the pedestrian rail posts could be installed after the precast trim installation. Close coordination between the contractor, the precast stone fabricator, and the rail fabricator will be required during the construction phase so that these elements tie together appropriately.
LAN’s team of dedicated engineers, in coordination with the city, provided high-quality solutions to the various challenges faced on this project to bring a much needed connection to the city. Once completed, the roadway will improve access from north Sugar Land to south of US 90A while also providing an alternate route to alleviate traffic congestion.
“This approximately 700 acres Northeast of the intersection of SH 6 and US 90A turned out to be a very prime spot and has really stimulated the area,” said Steubing.
Lauren Van Andel, P.E., is the North Texas Bridge Section leader for Lockwood, Andrews & Newnam, Inc. (LAN; www.lan-inc.com), a national civil engineering firm. She can be reached at firstname.lastname@example.org.