NEW YORK - Mayor Bill de Blasio on Friday officially announced new social distancing measures at some city parks as a way to prevent overcrowding.

Piers 45 and 46 at Hudson River Park will now have a limit on the number of people allowed in at a single time.

And NYPD officers will step up patrols at Domino Park in Brooklyn to make sure people are wearing face coverings and are not gathering too closely.

The mayor says the physical layout of these parks is partly to blame, because they encourage crowds.

But he also says much of the responsibility on New Yorkers to keep themselves and their neighbors safe.

"Why? Why are we doing this? Because it saves lives. And that's what we're gonna tell people from the beginning. If you're going in, you're going in for a limited period of time, we're not gonna allow it to get too crowded. If people don't want to wait, if they come and there's a lot of people there and they have to wait, a lot of people are gonna move one," De Blasio said.

The mayor on Friday also offered some new details on his Test and Trace Corps.

The Mayor also offered some new details on his Test and Trace Corps.

The team will be made up of people with a medical background who will work to identify infected people, trace their contacts, and provide support to patients and their loved ones. 

In the past, the city health department led similar efforts for diseases like HIV and Ebola.

But now, New York City Health + Hospitals will be at the helm.

The health department has been in charge since the outbreak began but the mayor says Health + Hospitals is better suited to lead the tracing program.

"The Health and Hospitals also because of its nature as an independent agency is able to move very quickly - major contracts - make things happen in terms of personnel and operations faster than traditinal mayoral agencies. This is going ot take an immense and fast effort and Health and Hospitals fits for all the reasons I've said but also just the sheer heroism they've shown in the last few months," De Blasio said.

The mayor hopes to have as many 2,500 test-and-tracers on the ground by June.

Expanded contact tracing is thought to be a major key in deciding when to re-open businesses.