Chicago Transit Authority Purple Line passengers will be riding on a different set of wheels this weekend.

Purple Line trains will be suspended from 8:30 p.m. today until 4:30 a.m. Monday for the removal of the century-old Church Street viaduct.

Shuttle buses will run from 7:30 p.m. today until 1:30 a.m. Monday as a substitute for the usual train service.

Buses that usually stop near the Davis station will pick up passengers on Davis Street instead of the usual Benson Street location.

In addition, Benson Street between Clark and Davis Streets will be one-way, southbound, beginning at 9 a.m., closing completely in the evening. Church Street also will close today between Maple and Sherman avenues.

Switching the bridges will be an “enormous ballet for very big structures,” said Frank Kruesi, CTA president. A large lift vehicle will wheel the new bridge down the street and lift it into place after demolishing the old viaduct.

Officials said the plan is to put the new bridge into place late Saturday night, depending on how long the demolition takes.

“The big deal is to have it completed before rush hour Monday morning,” Kruesi said.

If workers are unable to complete the construction over the weekend, the alternate bus routes would continue, officials said. Any delays will be posted on the CTA Web site.

-Laura Olson