Only one articulated hauler could make the climb. Up a 45 degree wall of mud and rock. Loaded with 37 tons of blasted rock. Helping to clear the way for the world's largest diameter hard-rock tunnel bored under a city and above one of the original Seven Wonders of the World at Niagara Falls, Ontario in Canada. For the Volvo hauler, a wonder of productivity around the world, a high degree of success comes steeped in history.
Mother Nature is powerful. And harnessing the power of water is one of the greenest ways to capitalize on her natural resources. On the New York State-Ontario, Canada international border is the Niagara River. It's 58 km (36 miles) long, running north between two of the Great Lakes, Lake Erie and Lake Ontario. In between, is Niagara Falls. More than 85,000 m3 (3 million ft3) of water go over the crest line of the Falls every minute, and twice that amount during daylight hours in the March-October tourist season, dropping an average of 57 m (187 ft) at the higher and more majestic Horseshoe Falls. The rapids above the Falls reach a maximum speed of 40 km/h (25 mph). Americans and Canadians have been capturing excess waters available for power generation for over 100 years. The Niagara Tunnel Project, headed by Ontario Power Generation (OPG), is the latest venture to capture that energy.
On the Canadian side of the Niagara River, there are two existing water tunnels under the City of Niagara Falls, both constructed in the 1950s using drill-and-blast techniques. The tunnels take Niagara River water 1.6 km (1 mile) above the Horseshoe Falls and feed it to the Sir Adam Beck power stations located 8 km (5 miles) downstream. "The Niagara Tunnel Project, when finished, will increase diversion capacity to OPG's Sir Adam Beck hydro stations by about 27 percent," said Dave Infanti, foreman with Dufferin Construction.
The project started in 2005 when the world's largest hard-rock tunnel boring machine (TBM) - nicknamed "Big Becky" by a 6th grade class (after Sir Adam Beck) - started its dig near the power station heading toward the Falls.
At the other end, the tunnel intake area is being prepped. Below the river bedrock, with the Niagara River kept at bay by a temporary cofferdam, the tunnel has been started - but only excavated to about 300 m (1,000 ft). "It's been roughed out, braced, meshed, reinforced with shotcrete and pre-grouted," said Dave Pimpinella, Dufferin project superintendent. "Eventually Big Becky will break on through to connect the openings." This end of the tunnel is where the Volvo A35E and A35D articulated haulers are making the daily climb down, up and out of the tunnel intake entrance 37 meters (120 feet) below the rocky river bottom.
The haulers creep down the 45-degree incline in reverse. At the bottom lies a waiting excavator that fills the haulers with 37 tons of blasted and excavated limestone rock. Then the Volvo A35 heads back up the incline. The steep climb is roughly 60 m (200 ft) long. When the loaded hauler gets near the top of the gaping rock canyon, it has to make a complete right turn and go up another short incline - this time at a 48-degree angle. Dump the rock and do it again. "When re-flooded with river water this area will become a 2-to-1 slope with a catch pit to help prevent rock from entering the tunnel," confirmed Infanti.
Ontario Power Generation needed to enlist the right companies to carry out this monumental task. Strabag of Austria was selected as design build contractor. Strabag charged The Robbins Co. of Solon, Ohio with designing, manufacturing and delivering a new tunnel boring machine that could excavate the 14.44 m (47.3 ft) diameter tunnel through the sedimentary bedrock at Niagara. Dufferin Construction Company, a division of Holcim Canada, was subcontracted for site preparation, blasting at both ends, excavation of the overburden and haulage of all tunnel muck, as well as installation of the concrete gate structures at both ends.
As for the Volvo haulers, "Volvos were the only trucks that could make that climb," said Infanti of Dufferin. "We tried out the others and they just couldn't make the grade. We needed a solution. Strongco Equipment told us it would be Volvo. It was."
Strongco is the largest Volvo Construction Equipment dealership across Canada with over 25 branches. Dufferin does a lot of business with the Strongco branch based out of Mississauga, Ontario. "Dufferin is a big customer of ours," said Anna Sgro, Strongco Vice President, Multi-Line Division. "Their work changes and varies so they like to long-term lease a lot of their machines. We help them with a variety of machines to see which one fits. We told them that Volvo would handle a 45 degree climb."
Sgro continues, "It's the Volvo transmission, engine and torque converter. The drivetrain is optimized with every part having been developed by Volvo to work together, to get the maximum rimpull and get you in and out of where you need to go."
Strongco Equipment has been working with Dufferin since 1985. Just like the requirements for the machines, trust is a big part of their dealer relationship. Dufferin wants and needs both to be ready to go at all times - whether it's turning the key to start the day or picking up the phone to find a new equipment solution.
Dufferin had one Volvo A35E and two A35D articulated haulers so the comfort level was already there. While hitching a ride up the 45-degree-inlet slope inside the Volvo cab with Dufferin operator Wayne O'Hagan, we hear how easy it is. "The Volvo's are really nice. A lot more comfortable than other haulers I've run. I've got good visibility, a rear camera, air conditioning - even a stereo." After making the climb, O'Hagan wheeled around, backed up and dumped his rock payload onto a large mound that is quickly providing a new bird's eye view of nearby iconic Niagara Falls.
O'Hagan and the other Volvo hauler operators at the Niagara Tunnel also get more out of the powerful dump hydraulics, 9-speed transmission for smooth shifting and heavy-duty axles with 100 percent dog clutch type differential lock. No daily or weekly service intervals mean they can get right to work - whether it's up the steep grade or traveling growing distances to unload excavated material at maximum speeds up to 57 km/h (35.4 mph).
"A great deal of the TBM was assembled on site," recounted Pimpinella. "This saved transport time and cost. It took four months of assembly and preparation before Big Becky was ready to start cutting away." She's electric powered and armed with a cutting head that weighs more than 440 tons, features 85 disc cutters and delivers torque that ranges from 9,025 kNm (high speed) to 18,800 kNm (low speed).
The TBM was designed for hard rock, but the geology is quite varied, consisting of limestone, dolostone, sandstone, shale and mudstone. Most of the rock is Queenston shale. The softer stone has been a challenge to safely excavate and support with resultant overbreak in the tunnel crown, slowing production. "The TBM was designed to basically thrust itself against the hard, side tunnel walls and drive forward while cutting," illustrated Infanti. "When the side walls are soft or brittle, the TBM doesn't get optimum cutting thrust." This is one of the reasons the project completion date has been pushed to 2013. The projected price tag has risen from $1 billion (CAD) to $1.6 billion.
As of September 2009, the TBM has bored 5,400 m (3.4 miles) toward the 10,160 m (6.35 miles) finish line. TBM progress to date has averaged about 5 m (16 ft) per day. On average the tunnel is 90 m (300 ft) below the City of Niagara Falls.
When the TBM advances forward, wire mesh, rock bolts and steel ribs are installed to support the tunnel crown. Shotcrete is then sprayed in up to 30 cm (12 in) thick to reinforce the tunnel perimeter. Later, a cast-in-place final concrete lining will be installed to arrive at a final inside diameter of 12.8 m (42 ft).
What do they do with all the material cast aside by Big Becky? There is a continuous conveyor system that reaches from the TBM cutter head all the way back out to where she entered the tunnel. Conveyor belt extensions are added every 300 m (1,000 ft).
The conveyors transport the estimated 2.4 million m3 (3.14 million yd3) of bulked material and dump it into a pile that is now surrounded by a drop tent structure, erected after production began due to dust issues involving a nearby butterfly conservatory. Apparently the dust was feared to interfere with the mating patterns of the butterflies. Material is moved by the Volvo haulers to the rising 2 km (1.25 mile) long storage area located adjacent to the jobsite on OPG property.
For Dufferin Construction this isn't the biggest job they've done. Several years ago they completed projects where their share exceeded $150 million for the Highway 407 Express Toll Route (ETR) in Ontario and sections of the heavily traveled, 6-lane Queen Elizabeth Way (QEW). But according to Pimpinella, guys are talking about how unique this project is. "It's a job unlike any you'll ever work on again. It's exciting to be in on this one. We do concrete in all types of conditions and areas from highway to municipal, but a tunnel like this is really interesting."
The work goes on around the clock, 365 days a year. The TBM churns 20 hours a day, from 11 a.m. to 7 a.m. Downtime is filled with maintenance for replacement of disc cutters, greasing and conveyor repairs. And despite all that time on the job and in working in a space over four stories high, is claustrophobia ever an issue? "No," said Foreman Infanti. "These are tunnel guys. It's what they do."
Moving it - whatever it is. That's what Volvo articulated haulers do. Here in Niagara Falls, Canada and for nearly 50 years around the globe. Up the steepest of slopes - separating it by a measureable degree from the other haulers. And when they do see the light at the end of the Niagara Tunnel, everyone on this job will step back, smile and then move on to the next job. Because that is what they all do.