Delivering a special product on a short deadline without disruption
Paving the deck is one of the final steps in a bridge’s construction. It’s the metaphorical icing on the cake that ensures a smooth, safe ride for drivers as well as aesthetic benefits. The original bridge’s concrete surface often cracked and crumbled under winter’s icy grind, requiring frequent repairs and delaying traffic.
Rosphalt is ideal for sites with unusually heavy loads, places such as ports, racetracks, and airports. It lasts 3.5 times longer than traditional asphalt, meaning lower lifecycle costs and fewer closures for repairs. But Rosphalt also requires special preparation and handling. And paving both decks of the new bridge would require more than 28,000 tons of this premium specialty material – an unprecedented amount for any project here.
Tilcon New York wasted no time getting to work.
Creating an A-team to solve the unique challenges
The project posed unique engineering challenges around surface preparation, material delivery, roller changes, and safety. Rosphalt needs hotter temperatures and extra mixing time. The mix is produced at 450°F (232°C), about the same temperature needed to grill a New York strip steak. When placed onto the road surface, ambient temperatures can easily top 100°F (38°C), even in the middle of the night.
To produce the mix, Tilcon New York selected its batch plant in Riverdale, New Jersey, a facility with an output of 400,000 tons a year that had been part of CRH since 1999. (The plant has since moved to a state-of-the-art facility in nearby Totowa, New Jersey.) The last-minute design change also came amid the busy summer paving season. Tilcon New York already had commitments of 1 million tons of asphalt for other customers. But delaying one of the state’s signature infrastructure projects was out of the question. The team would have to deliver for the community while continuing to fulfil orders for existing customers.
To solve these and other challenges, Tilcon assembled a world-class team of cross-functional experts, including project engineers, a senior paving foreman, asphalt production and transport experts, and quality control. Plant personnel and equipment operators went through extensive training to ensure safety and quality when handling the special superheated mix. Crews used plexiglass shields, curtains, and fans to deflect heat and fumes. Rain posed another challenge. The mix was so hot that it would produce clouds of scalding steam if it came in contact with a rain puddle. For both quality and safety, surface moisture was removed with a blower truck and hand blowers.
Tilcon New York created and approved the job mix formula in just six weeks, well ahead of the eight to 10 weeks that is common for a project of this scale with multiple contractors, suppliers, and agencies involved in the process. The first test strip was placed just 16 days after the decision to include Rosphalt was officially finalised.
Every detail of the paving operation was mapped out with precision. Up to 1,200 tons of Rosphalt would be placed each night. In just over two weeks, Tilcon placed 14,300 tons of Rosphalt on the westbound span. That span opened to traffic in October 2017 while construction on the eastbound span continued. Upon completion of the eastbound span, Tilcon returned in September 2018 to place another 14,000 tons of Rosphalt.
The bridge was complete.