April 1, 2011
After days sailing north to Alaska, cruise ship passengers arriving in Juneau are ready for something different.
Just up the pier, there it is: the Mount Roberts Tramway, where visitors can step into one of two 60-passenger tram cars, named Eagle and Raven, and fly high above the harbor.
From the top they’ll enjoy stunning views of the Chilkat Mountains to the north, over to Douglas Island, into Silver Bow Basin where gold was found in 1880, and back to their ship, nearly 1800 feet (548½ meters) below.
Natural beauty and hospitality are the focus for Goldbelt, Incorporated, the Alaska Native Corporation that owns the facility. A nature center on the mountain forms the starting point of an extensive trail system, including bear-viewing platforms and a live bald eagle exhibit. The Mountain House has a 150-seat theater, restaurant, bar, gift shops and Native artists at work. Most visitors return to the harbor by tram, though a hearty few hike 2½ miles (4 kilometers) back down the mountain.
Starting in early May and continuing through September, as many as seven cruise ships tie up on the Juneau waterfront each day. They unleash up to 15,000 fun-seeking passengers, boosting Juneau’s population by 50 percent. For the Mount Roberts Tram, it’s time to make money.
And that’s a challenge for Joe Puliafico, tramway operations manager. There’s scant time for Puliafico and his three-man crew to run safety checks or do maintenance, and simply no time for downtime. A day out of service could cost more than $60,000.
A Narrow Window
“We only operate May through September,” he said. “We’ve got a pretty narrow window to generate revenue, so it’s really important that things run smoothly.”
In season, the tram carries passengers up to 13 hours a day. Before the doors open, Puliafico’s team runs two hours of safety checks and inspections, and workers at the mountaintop facilities have ridden the tram up to their jobs. In the evening the hilltop workers tidy up, then ride back downhill.
Those long, crucial days aren’t Puliafico’s only challenge. Service in small town Juneau depends on Puliafico’s team—there’s no contract help to call. The town is accessible only by sea and air. An order for spare tram parts can require a three-hour drive from the manufacturer’s headquarters just to meet the lone airline serving Juneau. “Last year we sent our dc motor down to GE down in Portland to get some bearings replaced,” Puliafico said. “It’s quite the operation to take a 6,000-pound (2721.6-kilogram) motor out, break the thing up and ship it down on a barge. It took a lot of pre-planning.”
Planning is key to keeping tourists and dollars on the move in cruise season.
“The most important thing is a really good preventive maintenance plan,” Puliafico said. “I’ve got myself and three other guys, and those other seven months of the year, when we’re not operating for the public, we’re focused on maintenance. That’s actually my busy time.”
In testing “I kind of cover the whole gamut,” he said, “anything as simple as just checking voltages to getting a little bit more complicated, where I’m calibrating our TeleTrans system, calibrating current output from the drive cards to the auxiliaries to make sure those are working in tandem.” Control panels receive monthly calibration checks to verify control system voltages, and the TeleTrans system is checked using a Fluke 105 ScopeMeter®. A resistor is used between haul rope and ground, and Puliafico uses his Fluke 87V Digital Multimeter to verify correct resistance in those tests.
The results are impressive. Puliafico said that in 2010, the Mount Roberts Tram had just over one hour of downtime out of 15,000 operating hours. “It generally ends up being just minor stuff,” he said, and added “Knock on wood.”
Great Views, Top and Bottom
The control room operator’s station with the touch-sensitive, multi-screen display. Photo courtesy of Joe Puliafico
Each car has a PLC control panel for the operator. Photo courtesy of Joe Puliafico
The 600-horsepower, 500-volt dc drive motor. Photo courtesy of Joe Puliafico
The 12-pulse drive system. Photo courtesy of Joe Puliafico
The view from the Mt. Roberts observation deck is awesome. In its way, the view the system operator enjoys from his control panel is just as impressive. Controls were revamped between October 2003 and April 2004 using Allen-Bradley ControlLogix 5000 series programmable logic controllers (PLCs) to govern all basic operations of the tram. A fiber-optic link connects the upper and lower terminals. In the tram cars, battery-powered Allen-Bradley SLC 500 series PLCs communicate by radio modem.
Today the operator faces a touch-sensitive, multi-screen display that provides complete information about tram operations. The primary screen (there are eight in total) shows the positions of the cars and shows speed, current and voltage readings, ramp and door positions, and more. Any alarms are also flagged onscreen. Other screens provide more information: video of critical system components such as the cars and cable tension unit, and weather and wind conditions. Winds blowing 50 miles (80.5 kilometers) per hour can be enough to halt operations, and Puliafico has seen winds of 127 miles (204 kilometers) per hour at the top of the tram. When that happens in the winter, the crew finds work to do down at sea level.
At the top of the lift, an attendant oversees loading and unloading and monitors safety systems at the top. With the passengers safely in place, the operator down below assumes control for the return trip.
The layout of the $17 million Mount Roberts Tramway is simple. Its engineering and operation are not. Each car rides on two track cables of 2-inch (5-centimeter) diameter, each with a breaking strength of more than 300 tons. The cables stretch from the lower terminal at waterfront level to a 165-foot (50-meter) tower and 3,000-square-foot (278.7-square-meter) observation deck at the top, nearly 1,800 feet (548.6 meters) above. There’s no road up the mountain, so when the tram was built in 1995 the structure, made of 400,000 pounds (181,440 kilograms) of steel, had to be assembled by helicopter.
There’s no tower in the middle of the run to spoil the view, and as one car climbs the 3,100-foot (945-meter), 68 percent grade at 23 miles (37 kilometers) per hour, the other descends. A hydraulic system at the top keeps tension on the 1 3/8 inch (34.9 millimeter) diameter hauling cable; most other mechanical and electrical systems are located at the base. These include a 600-hp, 500-volt dc drive motor and gearbox, supplied with 1200 amps of 480-volt utility power that is converted to dc with a 12-pulse drive. The main programmable logic control (PLC) system is there too. Each car also has a PLC control panel for the operator. Two 360-hp diesels with hydrostatic drive operate the trams if power goes out. Generators supply backup power for times when city power is unavailable. “We just switch over to our backup systems and in five minutes we’re up and running again,” said Puliafico.