An alert motorist on Highway 101 helped Petaluma police arrest a driver whose blood-alcohol level was more than four times the legal limit, police said Sunday.

Shortly before 10 p.m. Thursday, a driver on southbound 101 reported a vehicle that was weaving within the lanes and had almost struck another vehicle, Lt. Tim Lyons said.

The driver followed the vehicle as it took the East Washington Street exit in Petaluma, where police found it parked a short while later.

Police spoke with the driver, Megan Samuelsen, 47, of Cotati, and smelled alcohol on her breath, Lyons said. She was arrested on suspicion of drunken driving.

Samuelsen was on probation for a DUI, Lyons said.

Her vehicle was impounded and she was booked into Sonoma County Jail.

Upcoming meeting to explore 4G wireless technology

Santa Rosa and Verizon are holding a series of meetings in coming weeks to allay concerns about its network of 4G “small cell” wireless antenna equipment being installed on utility poles around the city.

The four joint Verizon/city meetings will take place:

— Monday, Feb. 26, from 6 p.m. to 8 p.m. at 637 First St.

— Saturday, March 3, from 10 a.m. to noon at Veteran’s Memorial Building, 1351 Maple Ave.

— Thursday, March 8, from 6 p.m. to 8 p.m. at Veteran’s Memorial Building, 1351 Maple Ave.

— Saturday, March 10, from 10 a.m. to noon, at Veteran’s Memorial Building, 1351 Maple Ave.

In addition the City Council is planning to hold a study session on the issue Tuesday, March 6, beginning at 3 p.m. at City Hall, 100 Santa Rosa Ave.