A brief power outage early Sunday will affect traffic signals and streetlights in a section of downtown Portland as part of an ongoing Portland General Electric project to complete the Marquam substation.

The outage, expected to last an hour, will begin at 4 a.m. and affect some downtown buildings between Southwest Naito Parkway, Fourth Avenue, Jefferson Street and Morrison/Alder. The company has notified customers who will be impacted by the work.

The company is adding energized lines to the system to make the downtown grid more reliable.

Earlier this month, another section of downtown had a similar outage as part of the project. Watch a time-lapse video from PGE:

--Tom Hallman Jr.

thallman@oregonian.com; 503 221-8224

@thallmanjr