Mayor Bill de Blasio continues to lob criticism at his predecessor in City Hall, this time over its long-delayed overhaul of the city’s 911 system, which is the subject of a scathing new report. NY1's Bobby Cuza filed the following report.

On Friday, Mayor Bill de Blasio referred to the $2 billion modernization of the city’s 911 system, a Bloomberg administration initiative begun in 2004, as "a project that had really gone wrong."

The project is the subject of a blistering new report from the city Department of Investigation that found that "persistent mismanagement between 2004 and 2013" contributed to the project running 10 years behind schedule and some $700 million over budget.

"Too much money was being spent, and the results were not good enough. The checks and balances weren't good enough," de Blasio said.

Joining in the criticism Friday was the union representing many 911 operators and dispatchers, which has long been critical of an over-reliance on outside contractors. 

"Under the Bloomberg administration, we saw constant processes where that entire control was given to consultants," said Henry Garrido, executive director of District Council 37. "So you have a consultant supervising a consultant who was supervising consultants."

De Blasio has, of course, been a frequent critic of his predecessor on everything from education to economic development to policing, but perhaps on no other issue have former Bloomberg administration officials responded so forcefully.

Former Deputy Mayor Cas Holloway briefed reporters and issued his own report defending the project, writing, "By the standard that matters most, the 911 overhaul was an overwhelming success: it works. It is faster, has more capacity, new back-up infrastructure, and is more stable and reliable than ever before."

"Those individuals want to defend that, that is their right," de Blasio said. "But I think it's quite evident that this was a project that had gone wrong and needed serious change."

Those changes include fewer consultants and more centralized control by the city's own technology department.

The final piece of the project, a new backup 911 call center in the Bronx, is now due to be complete in 2017.