Top Down Road Reconstruction, Slope Stability Solutions on a Budget
Peter Bullock, P.Eng., M.Eng.
peter@gsican.ca Principal Engineer, GeoStabilization International, Vancouver, BC
Abstract
A new approach to road and landslide stabilization using small inclusions, and lots of them, not only proved to be an effec- tive permanent fix, it was also delivered quickly and on budget that was 50% less than traditional methods. The approach combined design/build project delivery, soil/rock anchor tech- nology and geosynthetic reinforced soil (GRS) with micropiles. This combination repeatedly produced efficient, high quality, long-term solutions that were previously unattainable.
This paper highlights a pilot project on Vancouver Island, British Columbia that embraced these concepts. It proved to so versatile in a variety of terrains that is was used on other highways and gained the attention of the BC Premier who granted it the 2013 Premiers Innovation Award.
The pilot project involved 7 Ministry of Transportation and Infrastructure sites on Vancouver Island. There was a common theme for the locations: remote, steep, and each were along critical access routes to the towns or communities they served with no easy solution for repair.
Road closures were not an option, and traditional methods proved to be too expensive to entertain. Due to these constrains the necessary repairs could not be completed in a traditional fashion and over years and decades caused maintenance work to be more frequent at an ever increasing cost.
Through extensive research and a collaborative effort, the above-mentioned techniques successfully mitigated every site with minimal traffic disruption and at a fraction of the time and cost associated to traditional approaches.
Introduction
Fill slope failures along roads, rail, pipeline, and trails are common and frequently extremely challenging issues. Excavating the failed material out and either replacing it with higher quality soil and construction or retaining struc- tures are the common or “traditional” methods of mitigation. Unfortunately these techniques are laborious, take time, and due to the excavation component are challenging to construct while maintaining traffic.
These types of failures are small but frequent; they also repeatedly prove to be technical but are generally under funded for traditional repair methods. This paper describes recent innovations that not only proved to be very efficient, they successfully mitigated multiple sites in a twelve month period and caught the attention of the BC Premier Awards
committee who granted Peter Bullock, P.Eng., M.Eng. and his team the 2013 Innovation Award.
The 7 sites across Vancouver Island, BC. each had some, or all, of the following attributes: steep ground, limited access, environmental constraints and/or limited right of way.
Design/build delivery with small inclusions, and lots of them, were the theme of this work. Soil and rock anchors, closely spaced micropiles and geosynthetic reinforced soil (GRS) were the tools. Small footprint, few resources, shortened construction timeline and reduced cost with a wide applicabil- ity was the result.
The Challenge
Unlike large jobs, the small, non-emergency, maintenance type work on secondary or rural roads have limited political pull, few resources, but all the technical challenges. Every site was unique and every site had challenges. This resulted in the need for specialized engineering and/or expensive investiga- tions and logistical considerations.
The following few examples were all long standing challeng- es that the BC Ministry of Transportation and Infrastructure had been repairing, studying and routinely maintaining for years, even decades at an ever increasing cost to the taxpayer.
The Test
After years of watching traditional methods either consume budgets or simply prove to be too expensive to proceed, a test project was entertained. In 2011 the South Coast Region took on a new venture that captured multiple projects under one design/build contract on Vancouver Island.
The Vancouver Island District was canvased and suitable projects were highlighted for cost and priority. The list identi- fied 12 challenges with a combined construction cost estimated at over 10 million using traditional methods.
The Region allocated 500,000 for the preliminary work. The intent was to mitigate 5 sites: Ford Cove Hill on Hornby Island, and 4 sites on Highway 4: Kennedy Canyon, Kennedy Lake East and West Slides and Kennedy Lake Pinch point. Highway 4 travels across mid Vancouver Island between Qualicum Beach and Tofino.
These projects proved so successful that additional work was completed under a different contract on Highway 14. Highway 14 travels up the soutwest coast of Vancouver Island from Victoria to Port Renfrew.
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