Work remains suspended on a section of the Second Avenue subway line after Tuesday's blast, which the Metropolitan Transportation Authority says was conducted at a different angle and intensity than planned, rocked an Upper East Side street and sent passersby running for cover.
Speaking to reporters Wednesday, MTA officials said the incident happened during a controlled tunnel blast at the northwest corner of 72nd Street and Second Avenue -- an area the agency says was not equipped to handle the force of the blast.
"The force of the blast was concentrated in one particular area. That was not anticipated. The other factor was, the area it was all focused on, was not ever anticipated to take that kind of blow," said MTA Spokesman Adam Lisberg.
Agency officials say the explosion knocked off the wooden piling and steel plate covering the blast section, allowing debris to fly into the street.
MTA Chairman Joe Lhota is calling the incident "completely unacceptable."
While it was somewhat of a chaotic scene with windows shattering, no one was hurt.
MTA Capital Construction President Michael Horodniceanu told reporters on Wednesday that the agency will retain an independent safety consultant for the project and that a blasting consultant will be more involved in the process.
Transit officials are also re-evaluating the decking system and adding protective matting in the blast area, according to Horodniceanu, and that the 72nd Street construction site was not equipped to handle such force.
John Carbone, a doorman who was working at the time of the blast, tells NY1 he did hear the customary warning whistles whenever crews are about to detonate.
"I heard the whistle go off, then the explosion, and ran out," Carbone said.
"I just went and hit the floor you know and covered my head waiting for another blast or something and it was just, you couldn't see anything around it was just total dust and the smell of sulfur and flying debris and glass," said one witness.
The Buildings Department says the explosion did not cause any structural damage to surrounding buildings.
Blasting has been halted at 72nd Street and Second Avenue but will continue along the rest of the avenue.
Meanwhile, an MTA spokesman confirms back on August 8 there was some shifting in a pit at the site of Tuesday's blast.
That incident - which took place on the southeast corner - also caused some small rocks and debris to be spewed onto the street.
A nearby art gallery was also issued a vacate order and reports say its floor is unstable.
In a statement, Chairman Lhota said he understands the community's concerns about the project and will work to address them.
Quality of life on the Upper East Side has been an issue since the Second Avenue subway project got underway.
Local residents and businesses say Tuesday's blast is just the latest problem they have had to endure.
Construction dust has been an ongoing complaint, but air quality appears to have improved thanks to more careful debris transfers and air filtration systems.
The community has also had to deal with loud sirens being sounded before crews blast inside the tunnels.
Business owners also say they are hurting from less foot traffic along the construction route.
"At least 50 percent of the business has gone down, for sure. You know, the construction, the noise, everything, the pollution in the air, has definitely affected us," said one Second Avenue merchant.
"I have a lung problem, so the air is sort of important. It's just endless," said one Upper East Side resident.
This is just the first of three phases of construction heading from 63rd to 96th Street.
The Second Avenue line is expected to open by December 2016, according to Horodniceanu.