A traffic backup was reported on North McDowell Boulevard Thursday morning due to a malfunctioning railroad crossing arm at the tracks on Southpoint Boulevard.

The railroad arms switched on about 8:45 a.m., stopping traffic, but with no train approaching. Traffic quickly began backing up onto McDowell Boulevard and motorists eventually began weaving their way around the railroad arms.

Petaluma police arrived on the scene a little after 9 a.m. to lift the arms and direct traffic across the tracks.

As of 10 a.m., police were still directing traffic and awaiting the arrival of railroad authorities to fix the signals.

In previous weeks, there have been reports of railroad crossing arms malfunctioning and creating traffic jams at the intersections of Lakeville and D streets, and at East Washington and Lakeville streets.