While it may appear that work has slowed during the daytime on the Fannin Street reconstruction project, construction crews have shifted their labors to the evening hours. Fannin needs to be shut down completely to work on the lateral lines (water and sanitary pipes running east and west across Fannin) and the only realistic time to do this is during the night so that the street can remain open to traffic during the days.

The Fannin Street project continues on schedule. Nighttime detours around Fannin are located at MacGregor and Holcombe.

"Work on the new lines running north-south and the ones across the street can not be done at the same time," says Larry Weppler, resident engineer. "While some daytime work will continue through March, the majority will be done by a crew working 7 p.m. to 5 a.m. That has the least effect on traffic and on patients and emergency vehicles getting to the hospital entrances off Fannin."

The construction crews have run into a few difficulties. For one thing, water, sanitary lines and storm sewers are sometimes not where they are supposed to be. Most of the lines are at least 50 years old and the original plans have occasionally proved unreliable. "We're working hard with the city to find the existing water lines so that service won't be disrupted," says Weppler. The old cast iron water line pipes under Fannin have become highly brittle and extreme care has to be taken when working around them. On two occasions, water service has been lost temporarily, once to the east side of the street and once to the west. "The storm and water lines have reached their designed lifespan," says Weppler.

Contractors are hopeful that by mid-March, the new 24-inch water lines will be in place and can be tested and chlorinated. "Then we'll connect to the institutions and check for leaks. After that, we'll excavate the roadway to grade and pour the concrete. Finally, we'll move the northbound traffic to the new concrete roadway and the southbound to the center of Fannin, as we begin the work on the west side of the street," says Weppler.

The water lines are cathodically protected ductile iron and sanitary lines are being laid with PVC (poly vinyl chloride) pipe. PVC pipe (much larger and thicker - about one-half inch - than what the consumer might use around the house) is flexible and non-reactive.

"Cement and cast iron pipes are reactive to chemicals," says Weppler. "Sewer gas eats cement. But PVC is non-reactive, which will be very important in this project. And it's flexible."

(The only other substance that is truly non-reactive is clay, and clay pipes - like PVC - look brand new after 50 years of usage. Clay is, however, very brittle and needs to be extremely well "cushioned.")

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©2006 Texas Medical Center

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