PORTLAND, Ore. - The seemingly endless maze of construction due to water main replacement work in Portland's downtown got a new twist on Wednesday.

Crews working to replace iron water main pipes dating back decades closed Southwest Market Street between Southwest 11th and 12th Avenue just as rush hour got underway Wednesday morning.

The work is part of an $8 million water main improvement project that started in May of 2006.

Workers are attempting to increase the capacity of the city's water distribution system, including the replacement of now-brittle cast iron pipe buries underground decades ago.

One section of pipe dug up a block from the current project on Market Street was stamped with the date 1894, making it 113 years old.

On average, there are about 80 water main failures a year, but in 2006 there were over 180 incidents. Cold weather has been blamed for cracking many parts of the old pipe system.

The Market Street closure will last for about a week. The entire project is expected to be completed this summer.