By Mark Crawford
Whiteface Mountain, located in Wilmington, N.Y., is a year-round tourist destination popular among outdoor enthusiasts. The area rose to prominence throughout the second half of the 1930s and the 1940s thanks in part to completion of the Whiteface Mountain Veterans Memorial Highway in 1935, which was initiated under then-New York State Governor Franklin D. Roosevelt. To reach the mountain, visitors access a bridge completed that same year as they cross over the Ausable River on State Route 86. Today, the bridge carries about 2,000 vehicles per day over the river.
After exceeding its useful service life, the bridge was targeted for replacement in 2015. The new design is very similar to the old, but also includes decorative lighting and widened shoulders for safer bicycle use. Overhead utility lines on and near the bridge were also relocated. Because the bridge is the key approach to Wilmington and Whiteface Mountain, the New York State Department of Transportation sought to complete the project as quickly as possible, minimizing inconvenience to residents and disruption of tourist traffic. To meet these needs, they turned to precast concrete.
“With the project location only two miles from Whiteface Mountain, winter can start at in late November and continue through April,” said Daniel Logel, a bridge consultant with Contech Engineered Solutions in Orchard Park. “The only way to get the structure built in such a short window of time was through the use of precast arch elements.”
Logel helped the engineering team work through the unique design challenges of the project to build the most cost-effective structure. After consulting with Thomas Hoffman, who at the time was a NYSDOT Region 1 structures engineer, the team selected a BEBO precast bridge system. The project’s precaster, LHV Precast in Kingston, N.Y., manufactured twin 70-foot precast arch spans for the bridge replacement, with an overall length of 146 feet.
Hoffman indicated there were additional site factors that led to the decision to use precast components. First, there was no room for a temporary bridge on the site, so the project had to be completed during March, April and May. Plus, at an elevation of 1,100 feet in the Adirondack Mountains, cold weather can prevail into late spring.
“The subsurface showed the soil was littered with 5-foot boulders, so micropiles would have been the only option,” Hoffman said. “An additional wrinkle was that, after the original bridge was constructed almost in the dry, a dam was constructed downstream. That made the existing footing 19 feet below ordinary water.
“Therefore, we decided to reuse the portions of the substructures below the waterline that had not been subject to freeze-thaw.”
Getting it done
The clock started ticking in March 2015, when Tioga Construction of Schuyler, N.Y., shut down the bridge and began demolition of the 80-year-old structure. Total construction – including demolition of the existing structure, placement of footings, precast, parapets, backfill, pavement and lighting – took a little more than three months to complete.
According to Logel, LHV Precast manufactured 28 arch pieces and 16 sections of parapet wall that had a formliner finish on the outside face and a stamped formliner finish on the inside face of the headwalls. The walls were stained to look like the natural stone of the region.
Need for speed
Perhaps the most important consideration in selecting precast for the job was the need for speed – not only to minimize inconvenience, but also because an Ironman competition was scheduled to cross the bridge in July 2015. Detours and delays were held to a minimum and the bridge was completed well in advance of the race.
“Faced with a three-mile detour, weather concerns and the need to maintain the historic look of the bridge, precast arch elements were selected as the material of choice for the new structure,” said Jim Willis, vice president of production and dispatch for LHV Precast. “The accelerated schedule afforded by the use of precast concrete was much appreciated by those who were inconvenienced by the construction activities.”
Mark Crawford is a Madison, Wis.-based freelance writer who specializes in science, technology and manufacturing.