Widened Road Juts Off Side of Mountain
A highway “hanging off a mountain” in far western Canada is being widened by an American contractor using some imaginative construction techniques.
Omaha, Neb., company Peter Kiewit Sons, a subsidiary of Kiewit Corp., is the project’s design-builder and key member of a business consortium that undertook the $600 million highway job in partnership with the province of British Columbia.
Since the first rock was blasted away three years ago, Kiewit and its partners have refined their knowledge of how to widen narrow places, turn debris into constructive material and keep thousands of cars moving through work sites daily.
Dubbed the Sea-to-Sky Highway, Highway 99 climbs several thousand feet from Pacific Ocean waters to a recreational area that will be overrun by athletes and spectators during the 2010 Winter Olympics. Alpine skiing and bobsledding competitions will be staged on slopes near Whistler at the northern end of the highway.
The winding road edges Howe Sound for about 28 mi. (45 km) from West Vancouver to Squamish before beginning its climb into the interior of a range of Coast Mountains. For years, the roadway had been targeted for improvement by provincial authorities.
“The project always was planned,” said director Rob Ahola, official spokesman for the Sea-to-Sky Highway Improvement Project. “The highway needed work and the work was planned, but the Olympics definitely was the catalyst that got it started. It gave the project a firm date.
The firm completion date is October 2009, in time for Olympic torch ceremonies in February 2010. Provincial authorities were persuaded to upgrade the highway at the thought of tens of thousands of Olympic spectators clogging a serpentine, two-lane asphalt roadway marked by innumerable blind spots and few passing lanes.
On the lower end of the 62-mi. (100 km) road is where the highway is “hanging off a mountain,” in Ahola’s words.
“There is a railroad below you and a rock face above you,” he said, “just not a lot of room to do things. You really were left with two options: to blast into the mountain or to go outward on the downslope side. You have 14,000 cars a day going through there so it kind of forced the solution to be working on the downslope side.”
He noted that choosing to widen Highway 99 by blasting two more lanes from the granite mountain would have shut down traffic lanes repeatedly as charges were touched off and hazardous debris removed. Provincial authorities couldn’t countenance such obstruction in normal traffic flow. Early on, they flirted with tunneling through the mountain, but ultimately rejected that approach for fiscal and safety reasons.
Instead, Kiewit and other consortium partners turned to half-bridges — so-called because they carry just two of the four lanes of traffic — and mechanically stabilized earth retaining walls as substitutes for a natural ledge wide enough for additional lanes. Just which substitute support system is used where depends upon conditions at a particular site. For example, where Canadian National Railroad tracks squeeze between the sound and the footing of the existing roadway, half-bridges and cantilevered platforms are being employed to let the widened highway extend out, sometimes overshadowing the tracks below.
Forty-eight of the cantilevered or conventional platforms are being built along the route, as well as several full bridges that twin with existing two-lane structures. The half-bridges are 40 ft. (12 m) wide to accommodate two lanes of traffic and range from a few meters long to 1,320 ft. (400 m) of segmented structures.
The half-bridges are essentially vertical or angled concrete piers and walls cast in place on deep footings with decking laid across them. Double-corrosion-protected horizontal steel anchors connect the vertical supports to bedrock through drilled openings 5 to 8 yd. (4.5 to 7 m) deep. Encased in plastic and grout, nearly 2,300 of the anchors will be employed to assure the integrity of the four-lane surface above.
Girders for the half-bridges or cantilevered decks are either pre-cast concrete or steel trucked to the site. Some of the decking is pre-cast, some cast in place. Kiewit operates a portable concrete plant at a wide spot in the road, churning out decking, pier material or the additional 22 mi. (35 km) of traffic barriers that are part of the highway upgrade. In all, some 1.7 million cu. ft. (49,000 cu m) of concrete will be consumed by the project, as well as 6,050 tons (5,500 t) of rebar.
The retaining walls use piers and heavy wire grid on the outer edge to ensure earth and rock fill material won’t shift. At least 200 of these structures are being built, running for a total of 6.2 mi. (10 km).
Kiewit crews and equipment toil mostly with granite on the southern end of the project. While the hard rock is a blessing as a foundation for a final grade, it is a headache to remove when it is in the way. But the rock has become an essential construction component of this project, with much of it being crushed and reused in concrete and as fill in the retaining walls.
Kiewit operates four crushers and a series of JCI and Eljay portable screening platforms to reduce boulders to useable sizes. The largest crushing unit is a Kohlberg-Pioneer 4248 jaw crusher, which receives rock in an opening about 4 ft. (1.2 m) square. If the rock needs additional crushing, it is fed through an ISC vertical shaft impactor or a Nordberg 5100A. Additional reduction in stone size is accomplished with a Svedala H6000 unit.
In all, some 2.1 million cu. ft. (1.5 million cu m) of rock is being torn into and reused or removed from the path of the road. Another 1.04 million cu. ft. (800,000 cu m) of earth is being excavated, dumped and graded.
“Farther north toward Whistler, it changes to volcanic rock,” Ahola said of the geology involved, noting that the upper region was an active volcanic area. “Kiewit could use the rock on the southern end, but the volcanic rock is not as good — not as durable.”
Not as much blasting was required there either, but numerous rock fall mesh nets were bolted in place above the highway.
To secure the nets, in some instances Kiewit used its excavators to drill holes on sheer slopes instead of dangling a workman with a drill to perform the task. An excavator — often a Caterpillar 330 — is custom-fitted with a Sandvik Tamrock drill at the end of its hydraulic arm. The drill is extended out and down the face of the cliff where an anchor point is drilled into the rock.
Most of the company’s fleet of equipment is Caterpillar, but the stable also includes Komatsu and John Deere excavators. Its articulated trucks are Caterpillar (730 and 735) and Volvo (A-30D, A-35 and A-40D). Kiewit also operates some Kenworth triple-axle trucks and, Ahola said, 170 Ford pickups. At the height of a building season, as many as 900 project crew members are scattered among several work sites along the highway.
The number drops to 600 during cooler seasons, which in late October began again to affect work schedules. Nearer the sound, construction continues throughout the year.
“Temperatures are pretty reasonable most of the year on the southern end, but after Squamish you begin to get into winter conditions,” Ahola said. “The northern section has to quit some of its work from November to April, but the nature of much of the work is rock removal and you can do that under any conditions. We are making good progress year round.”
However, asphalt pavement “is more of an issue,” he added. “You can’t do as much in the winter because of the moisture we get. The bottom lift [layer] can go with a little lower temperature, but not the final lift.”
Obviously, the project is not being completed in an uninterrupted line from one end to the other, with one completed segment contiguous to the next. It was never planned to be accomplished that way.
“The way the contract was let,” Ahola explained, “there are about eight or nine sections, each up to 4.3 miles long, with the contractors being paid after each section is complete, including being paved.” Consequently, some paving occurs each session and some segments of the roadway are complete and already in full use.
“I would think that at any given time they are working on 50 to 60 percent of the remaining alignment in one form or fashion or another — bridges, retaining walls, highway surfacing — there is pretty much active construction most of the time,” he said.
A local contractor, B.A. Blacktop, has a portable asphalt plant in Squamish and was awarded the pavement subcontract. When the last section of pavement has been rolled and cured, 473,000 tons (430,000 t) of asphalt will have been laid. Most of it is Superpave, but in two communities along the route, a quieter, open-graded friction course is the surface material of choice.
Trucks bearing the familiar brown-and-cream colors of Miller-Capilano Maintenance Corporation equipment already are patrolling the brand new sections of roadway. The company, part of a large Canadian firm, The Miller Group, was awarded the maintenance contract for Highway 99; its crews were on the job almost from day one of construction activity.
That’s because the Sea-to-Sky Highway Improvement Project is a design-build-finance-operate contract, also known as a public-private project, with a 25-year maintenance component. When Kiewit and its partners in S2S Consortium became the “concessionaire” for the project, it took on the obligation to design and build the widened highway and to operate and maintain it for a quarter of a century.
“It has been done before, around the world and in the States, but this is one of the first ones in British Columbia,” Ahola said. “The objective is to have one entity responsible for the piece of highway for a long period of time. At the end of the 25 years, it is handed back to the owner, British Columbia.”
Before it can be “handed back,” however, the renovated highway has to meet agreed-upon standards, including the condition of the roadway and bridges and other engineered elements. Some money is held back for the duration of the project and if any repair work is necessary to meet the standards, it is paid for from those funds. If there are no problems, the remainder of the contractual fee is handed over.
Some of the other companies in the consortium are Macquarie Group (project manager), Hatch Mott McDonald (engineers) and CH2M Hill, for which Ahola works.
Besides becoming more familiar with engineering techniques to widen a road where no land exists, the consortium’s partners also added to their understanding of how to keep traffic moving through a construction area. Ahola said the traffic control has been a critical factor in the success of the project.
Kiewit also has had to factor in critical environmental considerations uncovered in a pre-project survey. These range from a “kind of unique” red-legged frog whose habitat was endangered to the more ordinary concern about wildlife crossings being maintained and enhanced. And then there are the eagles’ nests.
“There are certain times of year that you can’t do any blasting within a certain distance of eagles’ nests, or clear trees within a certain distance,” said Ahola. “I’m sure Kiewit had to learn where the frogs are, when the eagles are nesting and figure out a plan of attack taking all of that into consideration. There was a full plate of environmental matters that had to be taken into account.”
British Columbia provincial authorities undertook the pre-construction environmental work, as well as property acquisition and some construction activity that preceded the S2S Consortium’s arrival on the scene. A third of the $600 million project cost was expended in those activities.
The project is nearly 75 percent complete, with substantial completion contractually required by next July. An end to all work, including landscaping and clean-up, is required by this time next year. CEG