In the fall of 2013 Government of Yukon constructed a geosynthetic reinforced soil integrated bridge
system (GRS-IBS) at Nadahini Creek. The geosynthetic reinforced soil bridge constructed at Nadahini Creek is the first geosynthetic reinforced soil abutment bridge constructed by the Government of Yukon.
This paper describes the project background, design and analysis of alternatives, construction of the selected alternative as well as lessons learned through project implementation.
The Haines Road starts in Haines, Alaska, passes through British Columbia and ends at kilometre 246 in Haines Junction, Yukon Territory. The road serves as the only land route to Haines, Alaska which provides a ferry terminal for residents in central Alaska. Nadahini Creek is located at kilometre 109.2 of the Haines Road in British Columbia. The Government of Yukon maintains the Haines Road from the Canadian Border to Haines Junction.
Nadahini Creek is a highly turbid glacial fed stream with alluvial fan morphology. Twin structural plate corrugated steel pipe arches (SPCSPA) were installed at Nadahini Creek in 1968. Throughout their life span aggraded material was occasionally cleaned out of the culverts by Highways and Public Works maintenance workers. In the summer of 2012 the culverts were aggraded with material and Highways and Public Works cleaned them out. When the bottoms of the culverts were exposed it was discovered that high amounts of sediment transport had worn through large portions of the inverts, compromising their structural integrity and posing a safety concern for traffic. Jack post supports were installed in the north culvert and Highways and Public Works began investigating design alternatives to replace the structures.
Government of Yukon considered various alternatives including installing new SPCSPAs, open bottom arch culverts, a bridge on piles and a geosynthetic reinforced soil integrated bridge system (GRS-IBS).
Many design factors were considered in the analysis of alternatives including formidable stream
discharge values, large sediment transport and scour depths, as well as the need to accommodate fish passage. After completing a life cycle cost analysis, the GRS-IBS alternative with concrete precast box
girders was selected and Government of Yukon began the design of the bridge. The GRS-IBS
incorporates abutments constructed of closely spaced layers of high strength geosynthetic
reinforcement in-filled with compacted granular material. The beams are seated directly on the
compacted GRS abutment; no pile driving or pile caps are needed.
The construction of the GRS-IBS at Nadahini Creek was constructed successfully and resulted in the
conclusions that the construction of GRS-IBS are well suited for remote locations with low anticipated
scour as there would be minimal excavation, minimal materials and construction time required for
implementation. Using a straight facing wall opposed to a corrugated facing may also lend to ease of construction.
