Thrillseekers can now test their nerve on the world’s longest timber-towered suspension bridge – after Experimental Resources (ERi) – known for its philosophy of “fewer walls, more bridges,” designed and constructed “Michigan’s second bridge.”
The bridge—which opened in October 2022—spans 1,200 feet (365 metres), includes a suspended 1,023-foot walking surface (312 metres), and is 118 feet (36 metres) above ground. With a 5.5-foot-wide walkway, it can accommodate up to 3000-person loads between the peaks of McLouth and Disciplies at the historic Boyne Mountain Resort.
“You can feel safe on it because it has been designed to hold a lot of loads,” according to Troy Garland, the structural engineer responsible for the enormous bridge, with the project peer-reviewed by Pat Machin. A resort spokesperson added that “bridge visitors (can) experience a thrilling adventure with panoramic views of Boyne Valley.”
Wood Central understands that the timbers used in the bridge’s two towers (which measure 52 feet tall and 70 feet wide) came from a fourth-generational sawmill located at the foot of the mountain resort (Matelski Lumber Company) – and used 133 timber members per individual tower —comprising 92 members of glulam and 41 of solid lumber.
“In addition, there are 63 steel brackets within each tower, with the timber members (not including the baseplates)in the towers using more than 8,000 bolts in the brackets alone,” Experimental Resources said, adding that the “ERi construction crews had to drill the equivalent of over 2.5 miles or 4 kilometres worth of bolt holes through the timbers.”
“Each tower weighs over 111,000 lbs (or 50 tonnes) and is anchored to the foundation with baseplates made from 1 inch or 2.5 cm thick steel,” and are supported by main cables, tensioners, wind guy cables and suspender cables.
“The bridge railings are 44.5 inches or 1.1 metres tall and are made of stainless steel wire netting supported by 5/16 inch or 0.8-centimetre stainless steel wire rope,” according to Experimental Resources adding that “in addition to the railings; there is a top rail above the bridge deck that is made of sustainable Kebony wood.”
In total, more than 150,000 pieces of hardware were used in the construction – with onsite construction starting in July 2021, pausing in December 2021 for the winter season before recommencing in April 2022, ahead of full completion in October 2022: “Total construction time was twelve months, plus three months of pre-fabrication,” Experimental Resources said, with the design taking six months to conceptualise.
- To learn more about timber bridges, click on Wood Central’s special feature.To find out more about the technical elements of the SkyBridge, click here for the Environmental Resources dedicated case study.
