The FDNY’s response times to blazes and other emergencies are rising dramatically — and the city’s firefighters union says Mayor Bill de Blasio’s “Vision Zero” initiative, aimed at reducing traffic deaths, is a big reason why.

The Uniformed Firefighters Association is accusing the de Blasio administration of putting New Yorkers at risk by relentlessly saturating city streets with road barriers to help slow down traffic.

“Vision Zero is fully intended to save lives from traffic accidents, but by [the city] adding in concrete barriers and flower pots and everything else like that, you’re basically eliminating the ability for emergency service vehicles to get around,” Bobby Eustace, the UFA’s recording secretary, told The Post.

“Intersections are now gridlocked, and our guys just can’t get around.”

He added that condensing streets actually lacks vision because it’s making it more difficult for fire trucks to make turns and navigate during firefighting, including raising aerial ladders.

Eustace and the union were responding to new data released this week through the Mayor’s Management Report for the fiscal year ending June 30, which shows response times by the FDNY’s fire companies and paramedics are up across the board in most categories.

Response times to structural fires rose eight seconds over the previous year, from 4 minutes 20 seconds to 4:28 — despite a slight decline in these types of blazes citywide over the same period, from 27,280 to 26,207.

Meanwhile, average response times to life-threatening medical emergencies by ambulances rose by 26 seconds over the past year from 6:55 to 7:23. Fire companies saw a six-second increase, from 4:42 to 4:48.

In fiscal 2013, during Mike Bloomberg’s final year as mayor, ambulances on average responded to life-threatening emergencies in 6:45 and fire companies in 4:16.

Eustace said a big problem is City Hall repeatedly “fails to get word to rank-and-file firefighters” before it takes away traffic lanes to install dedicated bike lanes, traffic medians or other traffic-calming measures.

“We had a company in the Bronx [traveling at night last month] hit one of these barriers going 30 miles an hour, and it almost flipped the rig because they had no idea it was there,” Eustace said.

“That was the first they saw it. They were simply trying to go around a person [while] responding to a structural fire, and they smashed into one of these [concrete barriers].”

Vision Zero isn’t the only reason response times are rising, according to the union. It also blames private construction, Uber and other ride-hailing apps putting more vehicles on the road, and the Fire Department’s refusal to reassign a fifth firefighter to all Big Apple engine companies.

Overall, fire company runs dipped by nearly 20,000 in the past year to 1.14 million, and medical emergencies remained steady at nearly 568,000. In fiscal 2013, the FDNY had less of a workload, including 983,615 fire company runs and 450,423 serious medical emergencies.

Among the FDNY’s bright spots in the mayor’s annual performance report is that civilian fire fatalities dropped 30.1 percent in the past year, from 97 to 67. Six years earlier, there were 47.

Scott Gastel, a spokesman for the Department of Transportation, insisted his agency works with FDNY “and other first responders on every Vision Zero project to see that their vehicles have access when needed, and that response times are not impacted.”

“This is a critical part of our street redesign process,” Gastel added.

To help improve response times, the FDNY says, it plans to hire more paramedics and emergency medical technicians as well as expand the so-called “fly car” program in the Bronx next month where paramedics use specially equipped SUVs to respond to emergencies faster.

Councilman Joe Borelli (R-Staten Island), who chairs the fire and emergency management committee, said response-time “stats are always concerning because seconds mean lives,” adding he will “look to address” lack of FDNY staffing in next year’s budget.