No tips for horn honkers!
A solution to obnoxious taxicab horn honking in the city

New York City is full of energy. But, the down side is there's lots of noise and distractions. A major contributor is car horns,most often honked by taxi drivers. The city has posted the warnings shown above and recently, they have vowed to crack down on honks and issue more fines. But, its not working.

A solution
An effective way to address the problem is to implement a public campaign in which cab riders vow to warn a cab driver that if he honks the horn, it will affect his tip. This can be done with a verbal statement upon entering the cab:

    "Good morning, 5th Avenue at 59th Street, please.
      If you honk the horn for any non-emergency, you will forfeit any tip."

Or by handing the driver a card as shown below. The cards can be sized to fit in one's purse or wallet - business card, credit card, or dollar bill. The cards are a more effective way for the rider to get the point across without seeming as confrontational. The bright cards might have a longer shelf life and would help push the campaign along. The notices for the drivers should be easy to store and carry, convenient to access, and convey a clear persuasive message.

The plan hits the drivers exactly where it can have the most impact. It shouldn't take long before a cab driver is motivated to change his honkin habits.
Once a critical mass of people use this threat, the drivers couldn't be sure which entering fares will cooperate.
The yellow and the band of checks convey the connection to taxicabs and the font and upper case is as is used for TAXI on the vehicles.

Items to promote the campaign
Flier to post around town, and ads to run in papers:

Sticker to post on doors of taxicabs:

Items for cab riders to hand to cabdrivers
Business card size:

Credit card size:

Dollar bill size: