New York City's Department of Investigation (DOI) has revealed in a new report Thursday that Michael Bloomberg's administration left the 911 upgradation project incomplete amid several delays and cost overruns of millions of dollars. The project's overhaul, which was triggered by Sept. 11, 2001, terror attacks on the World Trade Center, was riddled with “persistent mismanagement,” media reports said, citing the investigation.

The DOI also found that the project’s cost at $2.03 billion, was at least $700 million over its budget, The Wall Street Journal reported. According to the report, the City Hall did not supervise the contractors properly and “senior program management” exaggerated their progress in the project, which started in 2004. The major reasons behind the upgrade, which was scheduled to be completed by 2007, were problems that occurred during the 2001 terror attacks and the 2003 blackout of the system.

“[The project] not only is late and over its original budget, but also has tested public confidence in the city’s ability to deliver on necessary improvements to the 911 system that are critical to public safety,” the report said, according to New York Post.

The main deliverables of the project included a new call-taking center in downtown Brooklyn, a backup center in Bronx, specified telephone and data systems for emergency responders, a fresh computerized dispatch software for police, fire and ambulances, along with some other smaller technology upgrades. However, the DOI report said that officials working in the former administration did not supervise the private consultants, who had marked up their bills to up to 600 percent, New York Daily News reported.

"The people in charge of running the project failed to properly manage on a real close level the contractors and consultants they hired," DOI Commissioner Mark Peters said, according to The Associated Press (AP), adding: "And there was a real lack of transparency — we didn't have accurate reports on how the project was going and how much it was costing."

The City Hall had also reportedly abandoned its original plan of forming a single unified dispatch system for police, fire and ambulances, because the police and fire departments resisted giving up control of their separate computer networks and dispatch systems, despite the city’s quality control consultant Gartner Group warning that the move would increase costs.

“As a consequence . . . the NYPD’s and FDNY’s upgrades have been managed on different tracks, with the NYPD upgrade completed in May 2013 and the FDNY’s upgrade still not scheduled to be completed for several more years,” Peters said, in the report, according to New York Daily News, adding: “This delay has had serious – potentially life threatening – consequences.”

The original upgrade was budgeted at $1.345 billion, but now the costs have soared up to $2.031 billion and the project may still not be completed until 2017, AP reported, citing the investigation.

However, Bloomberg’s administration denied the accusations and blamed Verizon and Hewlett-Packard Co. for delivering faulty products, and for running behind schedule, AP reported.