When exactly are traffic patterns changing near the Atlantic Yards site? More likely July 29 than today (updated)

Update July 25: Brownstoner reports that the Pacific Street changes went into effect today, while the change on 4th Avenue will go into effect next weekend, after July 29.

For months we've known that several changes--including ones that have alarmed Boerum Hill residents expecting a spate of traffic--are coming to streets and intersections near the Atlantic Yards site, but when?

Patch on 7/22/11 reported that "major changes go into effect on Sunday," linking to Forest City Ratner's official Atlantic Yards web site, which said the changes would occur "[o]n or around July 24, 2011."

(Patch's article was linked by NLG, Curbed and Brownstoner.)

However, the latest Atlantic Yards Construction Alert (see p. 8, below), prepared by Forest City Ratner and distributed by the Empire State Development Corporation, below, indicates it will begin "on or around July 29," which is the coming Friday.

If so, then that's another reason to distrust Forest City Ratner's claim, in an Albany lobbying memo, that it "recently re-launched a project website to ensure the most up to date information is easily available to the public."

From the Construction Alert:

The first element of the 2011 work includes the installation of curb extensions at the Pacific/4th Avenue Dean/Flatbush and Pacific/Flatbush intersections and the reversal of traffic from westbound to eastbound on Pacific between 4th and Flatbush Avenues. Permits for this work have been secured and work has commenced. During the next two week period the layout for four intersections will be completed, the curbs will be installed at the Pacific Street and Flatbush Avenue new signal poles will be installed. This phase of the work is expected to take approximately 5 to 6 weeks.

Beginning on or around July 29, 2011, the following changes will be made to the roadway network:

Fourth Avenue (between Atlantic & Flatbush Avenues only) will be converted to one-way southbound to improve traffic flow at the Flatbush Avenue/Atlantic Avenue/Fourth Avenue intersection.

Pacific Street (between Fourth & Flatbush Avenues only) will be reversed, changing from one-way westbound to one-way eastbound. To accommodate this change, a new traffic signal will be installed at the intersection of Pacific Street & Flatbush Avenue, as will a new crosswalk across Flatbush Avenue. Vehicles will be able to make right or left turns onto Flatbush Avenue at this location. This block can be accessed from both northbound and southbound Fourth Avenue.

Fourth Avenue northbound traffic, including all commercial vehicles, can use Third Avenue via Atlantic Avenue to access Flatbush Avenue. Pacific Street will offer secondary access to Flatbush Avenue. No through truck traffic will be permitted on Pacific Street.

Work being performed as part of the Traffic Mitigation Site work is being conducted at night pursuant to DOT permits. Over the next 3-4 weeks work will be taking place at the following intersections during the overnight period: Pacific/Flatbush, 4th Avenue/Pacific. Work will be concluded by 6 AM so that related MPT [Maintenance and Protection of Traffic] is removed for the morning rush hour.

FINAL Atlantic Yards Construction Alert 7-18-2011