Lower Manhattan

Mr. Zupan: Placard abuse accounts for much of the on-street parking in parts of the city with concentrations of government offices, such as Lower Manhattan. Some use by city employees may be legitimate. But this abuse has been going on for much too long.

VEHICLE RESTRICTIONS

Ban cars and S.U.V.’s that are more than 20 feet long, as well as S.U.V.’s weighing more than three tons. This would eliminate Escalades, Yukons, Excursions and other similarly bloated vehicles that tend to block the streets even in normal traffic.

— Tony Wasserman, San Francisco

Mr. Zupan: How could you implement this? Have a tape measure as standard traffic police issue?

Dr. Falcocchio: Just as trucks are prohibited from using some streets, passenger vehicles longer than 20 feet could be prohibited on streets that were not designed for their use. Restricting large vehicles from some streets, however, has to do more with the safety of cyclists and pedestrians than with congestion.

Restrict trucks to certain hours. Allow either only night deliveries, as many European cities do, or no deliveries from 8 to 10 in the morning and 4 to 6 in the afternoon. — Rita Kramer, Midtown

Dr. Falcocchio: Delivery times could be restricted only with cooperation from businesses receiving deliveries. The focus should be on allowing deliveries only during certain hours.

Bar passenger cars from entering Manhattan below 96th Street if they carry fewer than four people. This was tried during the transit strike two years ago, and there was markedly less congestion.

— Steven Scalici,

Great Kills, Staten Island

Mr. Zupan: Requiring this for a short time during a strike may be acceptable, and carpooling may be a good idea in the suburbs. But in the long run this would add to the number of cars in the city. And can you name three people you would be willing to commute with daily?