BOSTON -- All city employees could soon be banned from texting while driving a city vehicle if a new proposal to be announced by Mayor Thomas Menino on Thursday goes into effect.

Menino has ordered his labor-relations staff to craft a policy forbidding all city workers from text-messaging while operating city vehicles, Boston Transportation Commissioner Thomas Tinlin told the Boston Herald.

Menino will team up with the Safe Roads Alliance on Thursday to unveil a new ad campaign aimed at raising awareness of the dangers of texting and driving.

Safe Roads Alliance, a nonprofit organization dedicated to driver safety, is running a public service campaign telling drivers that texting while driving "may be the last thing they ever do."

The mayor's plan took shape following last month's Green Line trolley crash when an MBTA operator reportedly confessed to texting behind the controls before slamming into another trolley, the paper reported.

The crash injured 50 people and destroyed three trolleys. Since the crash, the MBTA adopted a zero-tolerance cell phone ban for all workers -- the strictest transit cell phone policy in the nation.

A proposed texting ban for drivers in Massachusetts was dropped by the state Senate earlier this week.