New Jersey DOT Repairs 280-Year-Old Stone Arch Bridge
Preserving Princeton History: Historic Stone Arch Bridge Reconstruction Requires Collaboration for Swift Construction
What do you think of when you hear of Princeton, New Jersey? The answer for most people is probably Princeton University. While the Ivy League university is found in the town, Princeton, New Jersey is famous for other reasons. On January 3, 1777, the Battle of Princeton between General George Washington’s forces and the British took place. Coming just two days after the more famous Battle of Trenton, the Battle of Princeton helped secure New Jersey for the Americans. Remnants, from this illustrious battle, remain in the town of Princeton including the Stone Arch Bridge.
The Stone Arch Bridge is thought to have been originally built in 1738. The bridge was damaged during the battle of Princeton and rebuilt in 1792. In 1916, the bridge was widened from 18 feet wide to 32 feet wide. Today, the bridge, which carries Route 206 traffic, is heavily used with estimates of 16,000 vehicles crossing it each day. Of that traffic, 4 percent can be attributed to trucks.
In February 2016, heavy rainstorms caused swelling of the Stony Brook River, which lies beneath the Stone Arch Bridge. A parapet was damaged and the bridge had to be closed down for two weeks while emergency repairs were made. When the bridge reopened, it was load posted, so trucks had to continue to detour. A design for a permanent repair was being conceived.
Leading the team from the New Jersey Department of Transportation (NJDOT) was Project Manager Pankesh Patel. According to Patel, the project also included minor reprofiling of the roadway, drainage improvements, replacement of existing guide rail, slope stabilization, and replacement/relocation of existing utilities. A second bridge, the adjacent Flood Channel Bridge, which was built in 1892, was also replaced due to poor condition. Patel says, “The project was challenging due to the historical significance of the bridge. This increased the number of stakeholders, and we sought input and collaborated with all of them.”
The stakeholders included State Historic Preservation Office (SHPO) and the Princeton Historical Preservation Commission (HPC). In addition, the construction side included Arora and Associates, P.C., who acted as the project design consultant, Urban Engineers who designed the Flood Channel Bridge, and Richard Grubb Associates who served as the archeologists.
Even with the many stakeholders, the construction was done in just 120 days. Begun in July of 2017, the bridge was reopened to the public on November 2. “The construction was a true collaboration between state, historical commission, and local municipal engineers. The cooperation and review time were unheard of,” says Patel.
Steve Schapiro, Director of Communications for NJDOT says, “The speed of the construction was extra ordinary considering all the extra work related to historical challenges.”
A revolutionary era mill, another historical landmark for the area, once stood at one end of the Stone Arch Bridge. Today, just a stone wall remains. While excavation was taking place for the bridge, Patel says a millstone was found in the river that had been used to cut grains and make flower.
Modernizing with a Historic Feel
Since the area was packed with historical significance, designing the Stone Arch Bridge so that it adhered to modern safety standards, while preserving history, was essential. It was also complex. “We had to get approval for the parapets from the various historical societies. To do so, we had to show them that the craftwork adhered to the former craftwork,” says Patel.
How could Patel and the team bring the revolutionary aged Stone Arch Bridge up to modern benchmarks while maintaining the historic standards? Patel explains, “We took stone from the historic bridge and draped it over modern steel to maintain the original aesthetics. The only difference to the naked eye is the parapets which were raised to meet current safety standards.”
Due to Stone Arch Bridge’s link to the past, multiple considerations were taken throughout the construction process. These considerations included archaeological monitoring which was being done in case artifacts were found. A mason who specializes in historical work was part of the team, and he had to submit special panels. The contractor had to use rubber matts to bring in equipment in the area. Finally, smaller lighter equipment was used to mitigate the possibility of vibrations.
The project also included minor reprofiling of the roadway, drainage improvements, replacement of existing guide rail, slope stabilization, and replacement/relocation of existing utilities.
According to Patel, historians gave the final construction a big thumbs up. “The mayor of Princeton and the local historical society have commended the project and were extremely pleased with the outcome. At first, they were afraid that we would replace the bridge with something modern, but they’ve noted we maintained history,” says Patel.
The $7.4 million Stone Arch Bridge construction project, which met the budget, has received a number of awards. These awards include the 2018 Project of the Year Award by the New Jersey Society of Professional Engineers Mercer County Chapter. In addition, Arora and Associates, P.C., the project design consultant, received an Honor Award from the American Council of Engineering Companies at the 47th Engineering Excellence Awards recognizing the top accomplishments and contributions of New Jersey’s engineering profession in the Large Project category.
Patel agrees that the Route 206 Bridges over Stony Brook project is worthy of recognition. While working within a historic district, Patel and his team preserved a historic link to the past. They did so by utilizing historically accurate elements and collaborating with all the stakeholders.