SWERVING (Reckless Driving/Disregarding Traffic Signs)- according to my readings on this thread, swerving is defined as "shifting for 2 or more lanes very quickly.
Swerving IS NOT a traffic violation. Moving one lane to the left or right is not swerving, no matter where on the road you do it. And it is even less of a violation when you do it with a signal.
You cannot be officially charged with "Swerving" but of "Reckless Driving" if you do indeed commit the mistake. According to the LTO website (as of this posting date), the fine for first time violators of "Reckless Driving" is Php1000.