Thar she blows! Mighty bursts of steam to be blasted through Longfellow Bridge pipe

Traffic will be briefly halted near Charles Circle Saturday morning as crews working on the Longfellow Bridge start would could be a two-day project to clean out a steam pipe that runs across the bridge.

Traffic will resume once the steam venting starts up, shortly after 7 a.m., Cambridge Police say, adding:

The process creates a cloud of ordinary steam and a low frequency rumbling sound. The steam will be supplied from Veolia’s Kendall Station generating plant on Land Boulevard in Cambridge. The primary location for the steam release is at the construction staging area in the parking lot across from and to the east of the Charles/MGH Red Line station. Smaller vents of steam will also be visible at several smaller locations along the Longfellow Bridge. Dirt and debris will be collected before the steam is released into the air.