According to Wikipedia, a crawler is crane mounted on an undercarriage with a set of tracks (also called crawlers), while a tower crane is fixed to the ground on a concrete slab. Note that the previous Construction Alert described the upcoming installation of the tower crane but not the removal of the crawler crane.
Also, there will be some railyard activity after a hiatus, involving SOE (support of excavation) work.
From the document
B-2 Tower, Modular Residential• Installation of temporary power and lights will be maintained throughout the project.Atlantic Yards two-week Construction Alert, October 28 2013
• Backfilling will commence during this reporting period.
• Subject to receipt of all approvals from DOB/MTA/DOT, erection of the tower crane will commence during the week of October 28th
• Subject to receipt of necessary permits, erection of the tower crane and removal of the crawler crane will take place during the week of October 28th. This work will require the closure of Dean Street from 9 AM TO 9 PM. Access to the Arena’s loading dock will be coordinated via 6th Avenue.
• Work related to site utilities will commence during this reporting period.
• Daily cleanup activities of sidewalks and streets are ongoing as required.
• Tentatively there are no construction activities scheduled for the upcoming Saturdays during this reporting period.
LIRR Yard Activities Block 1120 & 1121• Contractor to begin mobilizing for SOE Installation Work along Pacific Street between Carlton and Vanderbilt during this reporting period.
• Contractor to begin MPT installation along Pacific Street between Carlton and Vanderbilt during this reporting period.