CATEGORY: Transportation

OWNER: BNSF Railway

PROJECT FIRM: Hanson Professional Services Inc.

OTHER CONSULTANTS: Delve Underground, Jacobs, Ames Construction Inc.

DESCRIPTION: Sandpoint, Idaho, is home to a significant amount of transcontinental freight rail traffic. BNSF’s mainline track in Sandpoint merged with the Montana Rail Link before spanning Lake Pend Oreille as a single track, which constrained railroad capacity. More than 60 freight trains crossed the lake on this track daily. Many trains in either direction had to slow down or stop as they waited while trains crossed the bridge one at a time. The connector is a key location on BNSF’s Northern Corridor from Chicago to ports in the Pacific Northwest. BNSF owns more than 100 miles of track in Idaho and transports nearly 1.5 million carloads of freight in the state every year. To provide additional rail capacity and increase network resiliency, BNSF, Hanson and Ames Construction collaborated to design and build a 2.5-mile stretch of second main track, including a 4,800-foot-long bridge over Lake Pend Oreille. Constructing the bridge adjacent to the active rail bridge over the pristine lake, a popular tourist and recreation location, required an innovative and environmentally conscious approach. Support of the public-use areas along the project was paramount and resulted in an initial phase of work to construct a pedestrian/bikeway tunnel below the primary construction entrance. The area has many walking and biking paths, including the popular Serenity Lee Trail. This trail is a 2-mile-long walking and bike path that crosses the lake and parallels U.S. 95. It was important to keep this area safe for community residents, tourists and recreational and outdoor enthusiasts. Lake Pend Oreille is home to many species of fish and offers residents and visitors vast opportunities for fishing, boating and kayaking. Because of its environmental significance and recreational impact, the project required extensive permitting. The team focused on identifying regional best management practices to protect the lake, fish and other aquatic species. This included limiting the amount of cast-in-place concrete to avoid spills in the lake and lowering the number of strikes per pile to reduce vibrations and sounds to protect the fish in the lake. Additionally, the contractor transported construction equipment and materials on barges instead of building a temporary work trestle across the lake, which helped keep the lake accessible to boaters. The soil conditions in the lake also presented challenges. The soil was so soft and sensitive that installing a pile caused a reduction in the short-term soil strength. The geotechnical engineering team performed an alternative analysis to better predict the axial pile capacity in the complex soils and worked with a Purdue University professor who provided guidance based on his research into large-diameter, open-ended pipe piles. This collaborative approach led the project team to extend the pile length to nearly 240 feet in many locations, providing certainty on the long-term pile capacity. In an effort to improve construction efficiency, the project team used nearly identical elements—supporting piles, precast concrete pier caps and prestressed concrete girders—for the Lake Pend Oreille bridge and two additional bridges in Sandpoint. Incorporating efficiencies and sustainable elements into the design, working to protect the lake, fish and other aquatic species and addressing the needs and concerns of the community and stakeholders allowed the project team to complete this significant infrastructure capacity improvement nearly a year ahead of schedule and on budget. The Sandpoint Junction Connector project is a great example of how a major railroad project can make a positive difference to the client, community and environment. The Sandpoint Junction Connector improves capacity for BNSF, enhances commerce in the Pacific Northwest and potentially decreases locomotive emissions. The design also enhances the resiliency of the supply chain and minimizes impacts to the lake and its fish population.