The Colorado Passenger Tramway Safety Board released its 151-page final report on last December’s fatal accident at Granby Ranch this afternoon. The investigative team included seven professional engineers with more than 250 years of combined lift experience with support from Leitner-Poma and Granby Ranch personnel, among others. The team conducted extensive tests on the Quickdraw lift from the afternoon of the accident through January 5th and spent months writing this detailed analysis, identifying contributing factors and making recommendations for changes. Appendices include witness statements, photographs and prior inspection reports but the core of the document is 13 pages which everyone who works on ski lifts should read. I’ve done my best to summarize below.
Chair 58 contacted tower 5 at a 40-degree angle that morning due to two contributing factors. The first was the tuning of a new drive installed last Fall by an independent contractor. Two specific parameters may have created pulses of energy and rope instability, the report notes. “It is probable that the combined effect of [these two settings] may have resulted in the drive trying to respond too aggressively to lift demands when changing from ‘Fast’ to ‘Slow’ and back to ‘Fast’ again.” The second contributing factor was the influence of one or more speed changes leading up to the incident.
Other potential contributing factors were:
Control system complexity resulting from the new ABB DCS800 drive’s interface with older Pilz/Leitner low-voltage controls.
A control board replacement from February 2016.
Possible damage to the electric motor encoder.
Unknown electrical cycle shown in data logs that had occurred at a 3.7 second interval over the entire life of the lift.
Tension factor(s) that would require more testing to determine.
Natural instability of the profile. “There appears to have been a very unique combination of rope tension, carrier spacing, tower spans, tower height, carrier loading and natural carrier movement that led to the transverse carrier swing that resulted in Carrier 58 hitting Tower 5,” the document states.
Natural harmonic response of the haul rope.
Wind was not found to be an outside influence, nor was passenger conduct. “The incident that occurred on December 29th, 2016 at Granby Ranch was unprecedented,” the investigative team wrote. “Although many factors may have combined to amplify the effect of the rope instability leading to Carrier 58 colliding with Tower 5, the performance of the new drive is considered to be the primary cause of the incident.” The report explains electronic drives such as the DCS800 added to Quickdraw last year and used on many lifts are also used in a wide variety of other applications. The tuning and “fine-tuning” of a drive is complex and unique to each application and lift. “It appears the new drive was not comprehensively tuned to this particular lift during installation,” the document says.
Intrawest re-invested 8 percent of revenues at its resorts between 2013 and 2017 (compared with 11 percent across Vail Resorts.) The company had 173 interested buyers, 16 of which were ski industry players.
Early summer update from the Magic Mountain rebirth and Green Chair project.
Doppelmayr/Garaventa Group buys Frey AG Stans, a leading global provider of ropeway control systems.
Lifts from the defunct Talisman Mountain Resort have been sold; one is headed to Sunridge, Alberta.
The Denver Postreports a joint Aspen/Intrawest/KSL/Mammoth pass is in the works for 2018-19, meaning the Mountain Collective could lose seven members and 43 percent of its lifts. The MAX Pass might fare better, losing the six Intrawest resorts and 85 lifts (20 percent.) I chart one scenario below.
Leitner-Poma wasn’t involved in recent work that likely caused last month’s fatal fall at Granby Ranch, but the original manufacturer of the lift will fix it. Ten days after re-opening using only the lift’s diesel auxiliary, Granby Ranch has a plan to restore Quickdraw to full capacity with a new electronic drive. In a statement issued today, The ski area acknowledged a third-party company modified the drive system over the summer, as I reported last week. “Preliminary investigation has revealed that the issue that likely caused the incident was the independent contractor’s modification to the lift’s electrical drive/control system,” the release notes. The third-party installed system only operated 13 days before a chair hit a tower Dec. 29th, killing 40-year old Kelly Huber of Texas and injuring her two daughters.
Earlier today, Granby Ranch said Quickdraw would be closed today and tomorrow for additional testing, as ordered by the Colorado Passenger Tramway Safety Board. The area hopes to re-open again under diesel power in the next few days and Leitner-Poma will install the new electronic drive system in the near future. The CPTSB will release its official report on the December incident in the coming months.
Update 1/21/17: A state spokesman says the CPTSB ordered the lift closed until further notice at an emergency meeting after reviewing “unusual/irregular conditions” observed while Quickdraw was operating with the diesel auxiliary.
For the first time in 24 years (and post-Lift Engineering) an electrical or mechanical problem has led to a fatality on an American ski lift. The Quickdraw quad at Granby Ranch will re-open Tuesday after the Colorado Passenger Tramway Safety Board reached an interim operation agreement with the ski area. The news comes almost two weeks after the December 29th accident, in which a mother and her two daughters fell from a chair. Unfortunately, the agreement notes that a “rare dynamic event” due to issues with the electronic drive/control system caused the riders’ fall. Environmental factors, weather and/or rider behavior were not to blame.
The Colorado Department of Regulatory Agencies, which oversees the tramway board, conducted extensive testing in addition to interviewing witnesses and engineers over the past 10 days. Mother Kelly Huber and her two children were riding chair number 58 when it came into contact with tower 5 due to irregular line dynamics. The lift had been load tested less than four weeks prior, on Dec. 5th.
The operation agreement with the CPTSB is stringent. Quickdraw’s electronic drive must be disconnected (this particular lift has two diesels – auxiliary and evacuation.) Lift mechanics, operators and ski patrollers all must perform a line check prior to operation each day. Additional visual line and ground checks will be required to be documented every two hours. For the first three days, the lift will only be permitted to move 600 feet per minute, even though the diesel auxiliary is rated for up to 900 fpm. After two additional days at 700 fpm, Granby Ranch will be permitted to operate the lift at 800 fpm for the rest of the season. Presumably this summer the lift will get a completely new drive.
The operation agreement is not a final report and does not identify any acts or omissions leading up to the accident, but merely outlines the conditions under which the lift can re-open. In a press release dated today, Granby Ranch echoed its condolences to the family of the victims and affirmed its commitment to safety. “The Quick Draw Express has been operating safely at Granby Ranch over the 16 seasons since its installation,” the company noted. “Granby Ranch has followed all prescribed protocols in operating the lift.”
We haven’t heard the end of this one. Hopefully the final report will provide some insight into how this type of event can be avoided in the future.
Update 1/10/17: Apparently a third-party company installed a new ABB drive last summer that ramped up and/or down too quickly, leading to the dynamic event.
Tragedy struck yesterday at Granby Ranch, Colorado during what is normally a celebratory week at American ski resorts. A 40-year old woman and her two daughters, ages 9 and 12, fell from a chair on the Quickdraw quad at approximately 9:30 am. Kelly Huber, of San Antonio, Texas died, while one of her children remains in stable condition at a Denver hospital. The older sister was treated and released. In a statement today, the resort noted, “All of us at Granby Ranch are deeply saddened by yesterday’s tragic incident at our resort. We extend our heartfelt condolences to the family of our guests. Our focus right now is on supporting those affected by this tragedy.”
Quickdraw is one of only three Italian-built Leitner detachable chairlifts in the United States, debuting at Granby Ranch in 1999. Leitner and Poma merged their North American operations in 2002. While some reports indicate the lift stopped frequently before the accident, those of us who work around lifts know that is not unusual this time of year and often not due to any mechanical problem. There’s no indication the detachable grip failed and the fourth spot on the chair was apparently empty. Quickdraw’s chairs are equipped with both restraining bars and footrests. The Colorado Passenger Tramway Board is investigating and Quickdraw remained closed today.
According to the NSAA, the last fatal fall from a U.S. chairlift occurred on December 18, 2011 at Sugar Bowl, when a 7-year old boy fell 60 feet. Non-deadly falls are more common, however, with 227 reported in Colorado alone between 2001 and 2012. 86 percent of those were found to be a result of rider error, with 4 percent due to medical problems and just 2 percent attributed to operator/mechanical issues (the rest were never classified.) Yesterday’s accident was the first deadly chairlift fall in Colorado since 2002, with 1.7 billion safe rides in the years between, according to Colorado Ski Country USA.
Nevertheless, as I write this, a family is in mourning and the story occupies the fourth spot on CNN.com. With more holiday weeks to come, let this terrible accident be a reminder that no matter how statistically safe they are, ski lifts can become dangerous in an instant. Already this year, we’ve seen falls from chairs at Mt. Hood Meadows, Seven Springs and Whistler with near misses at Sundance and Mt. Ashland. Many more never make the news. Be safe out there – especially with kids on lifts.