Apple Spraying

Jan. 21, 2002

If there is one prevailing maintenance concern for any city, county or state transportation authority it’s the pothole. New York City is no different. In fact, potholes were so bad in “The Big Apple” that Mayor Rudolph Giuliani declared a comprehensive citywide Pothole Repair Blitz in December 2000.

If there is one prevailing maintenance concern for any city, county or state transportation authority it’s the pothole. New York City is no different. In fact, potholes were so bad in “The Big Apple” that Mayor Rudolph Giuliani declared a comprehensive citywide Pothole Repair Blitz in December 2000.

The New York City Department of Transportation responded by repairing more than 70,000 potholes since the declaration. Recent polls have indicated that the New York metropolitan area now ranks 16th in potholes/related-car-repair-costs out of the 50 largest metropolitan areas. Though there is a lot of progress to be made, this is a valiant effort considering New York’s vast transit system, huge traffic numbers and 14.4 million people.

The New York City DOT receives most of the credit for this pothole pro-gress, but another agency’s efforts that should not be overlooked is Metropolitan Transportation Authority Bridges & Tunnels. Bridges & Tunnels is a constituent agency of the Metropolitan Transportation Authority (MTA), which also manages the New York City Transit Authority, the commuter railroads (MetroNorth and Long Island Railroad) and all of the major toll bridges and tunnels within the city.

It is MTA’s Bridges & Tunnels that deserves considerable credit for maintaining and reducing the pothole concerns for some of the most heavily traveled areas of New York City. MTA’s seven bridges and two tunnels carry nearly 300 million vehicles annually, which is more than any bridge and tunnel authority in the nation. The bridges include the Triborough, Throgs Neck, Verrazano-Narrows, Bronx-Whitestone, Henry Hudson, Marine Parkway-Gil Hodges Memorial and the Cross Bay Veterans. The two tunnels overseen by MTA are the Brooklyn-Battery and the Queens Midtown. As with any other road surface, bridges and tunnels suffer from the same pothole plague and formation process. First there is an infiltration of water under the road surface, followed by subsequent freeze/thaw cycles and constant traffic—and voila, the birth of a pothole. But what makes the pothole problem different with bridges and tunnels is the unique maintenance challenge these structures present.

No other way

With other metropolitan side streets and thoroughfares, there are alternatives. If one particular street is in need of major pothole repair, there are usually other streets in which traffic can be detoured. Though an annoyance to the traveler, the option is at least feasible. But in the case of bridges and tunnels, the demands are much greater. Completed in July 1936, the Triborough Bridge has seen more than 2.8 billion vehicles cross its 65-year-old surface. Last year alone, more than 64 million vehicles crossed the Triborough, and it currently boasts an average daily traffic of 170,000 vehicles. When major potholes crop up, there is no simple detour for the Triborough Bridge, and the 170,000 people driving across it each day would not readily accept lane closings and/or major delays to repair potholes. Thus, MTA Bridges & Tunnels has implemented a quick yet effective method of pothole repair for its most demanding structures—spray injection pothole patching.

Spray injection pothole patching in-volves a four-step process. First, using a high-volume blower, the pothole is cleaned, removing rocks, debris and moisture. Next, a tack coat of hot emulsion is applied to the area in need of repair. Third, a mixture of aggregate and hot emulsion is dropped into the hole to fill the depression. Lastly, a top layer of dry aggregate is applied and traffic can flow immediately. Though one of the fastest and cheapest pothole repair methods available,  a study conducted by the Strategic Highway Research Program in 1992 found it to be one of the most effective and long-lasting techniques as well. In fact, some state DOT research councils have found spray injection pothole patches to last up to five years—or three to five times longer than traditional methods.

MTA Bridges & Tunnels currently has two Rosco RA-300 spray injection pothole patching trucks dedicated to maintaining their seven bridges, which includes two of their most demanding structures—the Verrazano-Narrows and Triborough Bridges.

Named after Giovanni de Verrazano, who, in 1524, was the first European explorer to set sail into New York Harbor, the Verrazano-Narrows Bridge spans from the historic Fort Hamilton in Brooklyn to Fort Wadsworth in Staten Island. When it opened in 1964, the Verrazano was the world’s longest suspension span and today is only surpassed by the Humber Bridge in England. Its large 693-ft-high towers are 15?8 in. farther apart at their tops than at their bases because the 4,260 ft distance between them makes it necessary to compensate for the Earth’s curvature. Whereas the Triborough’s main challenge involves traffic, the Verrazano requires a mobile pothole solution that can easily cover its incredible distance.

The patch works

According to Patrick Parisi, director of fleet operations for MTA Bridges & Tunnels, the quick and effective characteristics of spray injection pothole patching have proven valuable.

“Small holes and large cracks that previously may not have been repaired due to the time consuming setup for crews are now being addressed due to the maneuverability of the spray patcher truck,” he said.

Additionally, the safety aspects of spray injection pothole repair have been attractive to MTA. “Our primary concern is the safety of our employees and travelers,” said Parisi. “Spray patcher trucks provide us with a safe method to address potholes in high traffic, safety sensitive areas. Our workers never leave the vehicles and their physical strain is reduced because they don’t have to handle 60-lb bags of cold patch or operate heavy vibrating tampers.”

Spray patcher technology also allows MTA to better achieve their goal of minimizing traffic delays caused by maintenance.

“The spray patching crew consists of one person to operate the patcher truck and another to drive an impact attenuator truck,” said Bill McCann, MTA maintenance superintendent for the Verrazano Bridge. “With the quick repair process and minimal setup, the work zone quickly moves from pothole to pothole. There’s no need to set up and break down long cone lines.”

Marc Mende, MTA senior bridge and tunnel maintainer, appreciates the shelter the patcher truck cab provides from the elements.

“In the winter, when potholes are at their worst, we’ll patch about three to five days a week,” said Mende. “With the freezing and thawing cycles, potholes grow and it’s not unusual to repair more than 100 potholes in a shift. And on those cold days when it’s 18? out and the wind is blowing at 30 miles per hour, the safe and controlled environment of the patcher truck makes the operator more productive.”

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