METRORail riders will need to leave more time for travel this weekend, July 23-24.

The Metropolitan Transit Authority of Harris County will replace train service on its Red, Purple and Green lines with free two-way bus shuttles scheduled to run every 20 minutes, according to an agency press release. The rail lines will be closed July 23-24 for rail maintenance and improvement projects.

Transit service modifications to the METRORail Red, Purple and Green lines will begin at the start of service on July 23 and finish at 5 p.m., with Green Line interruptions continuing until the end of service July 24.

Riders should plan ahead for the additional travel time required for bus services, METRO officials said in the press release.

During this time, the agency said its Trip app and Next Bus Arrival Texting service might not provide accurate departure and arrival information. Instead, riders can find real-time information through METRO’s service alerts system.