Subway riders get on the F train at Jackson Heights View Full Caption DNAinfo/Tuan Nguyen

QUEENS — Your rush hour commute may get a little slower — and more crowded — this month.

The E, F, M and R trains in Queens are expected to have delays and possible crowding during the morning and evening commutes for the next three weeks, thanks to repair work being done on the Queens Boulevard route, the MTA warns.

Crews will be rebuilding sections of express tracks on the line starting this Monday through Friday, Sept. 4th, impacting rush hour service, according to the MTA.

Express E and F trains in Queens will have to run 10 miles per hour slower through work zones, and some will be running on the local tracks instead, reducing the number of trains able to run on all four affected lines, the agency said.

Trains in Manhattan and Brooklyn are not expected to be disrupted by the work, an MTA spokeswoman said.

The MTA described the repairs as "necessary to keep the express tracks in a state of good repair along the Queens Boulevard line," which it noted is the second busiest line in the system.

The work was planned for the last three weeks of summer because that time is known for being among the lowest-ridership periods of the year, according to the MTA.

For more information about the changes, visit the MTA's website.