Construction to replace the Church Street viaduct on the El’s Purple Line will begin July 24, according to a Chicago Transit Authority press release.

The nearly-century-old viaduct’s condition has deteriorated to the point that trains have to slow down in order to cross it safely, delaying Purple Line service and lengthening travel times. At an April meeting, CTA officials named replacing the viaduct a priority for future construction.

The construction will replace the current viaduct using funds from the Federal Transit Administration Rail Modernization, an organization that awards yearly grants to different types of transportation improvement projects. The Church Street construction will cost an estimated $3.3 million and will be carried out by Illinois Constructors Corporation.

The Church Street viaduct, located one block north of the Davis Street station, is the second viaduct on the Purple Line to be replaced as part of a plan to update all six of the line’s bridges. In fall 2005, the CTA replaced the aging Main Street viaduct with a modern steel version.

CTA public relations contact Robyn Ziegler confirmed by e-mail that the construction would only minimally effect Purple Line travel. The CTA’s press release indicated the transit authority expects to install the new viaduct in fall 2006. Service will be suspended for approximately one weekend, and bus shuttles will be available to allow passengers to use the Purple Line.

Improvements to the viaduct will also include new waterproofing and drainage systems, better lighting under the bridge and tie replacement. Construction should be completed by late fall 2006.