Surface water drain blockage
If the private road is owned/maintained by an "association" (some sort of formal group ownership arrangement as is often the case for private roads serving more than one person/house) you should bug the association since they probably all need to be cleaned, and you may already be paying a maintenance fee that should cover such things.

If it's yours and yours alone, you should ask your builder for details of what they did, and undertake to maintain it yourself or hire someone to maintain it for you, on a regular schedule. Our town crew seems to use a giant vacuum truck to suck the crud out, but there are likely several approaches that don't involve a giant vacuum truck, such as a can on the end of a stick.

Since it's close to the house, a wet/dry shop vacuum might help.

Best bet on opening - Hook the grate and pull up - looks to me like it's hinged (so that if left open and traffic came in the marked direction it would slam shut, rather than try to act as a traffic barrier and damage itself and cars.) If so, hooking near the bottom of the picture would be easiest. Otherwise, the middle is always a good bet, if not the easiest.