A school bus beeps its horn as a child strays into Henry Street outside P.S. 1. On the opposite side of the Chinatown schoolhouse and its playground, on Madison Street, cars swerve to avoid a city bus that pulls to a stop. On one side of the school, children meander into Catherine Street where the sidewalk narrows.

“It’s dangerous,” a crossing guard said. “Sometimes I stand in the middle of the street, all these kids going this way and that way, and it’s dangerous.”

The city’s Department of Transportation agrees.

Officials of the agency identified P.S. 1 as among the 135 schools in the five boroughs with the most dangerous surrounding streets and sidewalks, from the standpoint of traffic safety. Already, workers have laid new sidewalks around most of the circumference of P.S. 1. They’ve also replaced the old-fashioned yellow signs with brighter, fluorescent yellow-green ones.

It’s part of a new drive to make it safer for children to get to the city’s schools in the morning and get home at the end of the day.

“When you’re working here, there’s nothing that strikes you as more important than making the city streets safer to children,” said the senior policy adviser to the transportation commissioner, David Woloch. “Parents want their children to feel and be safe. We have a responsibility to make these safe havens, as much as possible.”

Mr. Woloch said that in the past his department addressed hazards in an “ad hoc” way, sending crews out to schools where principals and politicians complained the loudest.

“That didn’t mean the most severe problems were getting dealt with,” he said.

The director of signs and markings for the department, Gerard Soffian, added that the new school-safety programs, Safe Routes to School and Walk to School, are more comprehensive efforts to locate problem areas and improve them.

The transportation department quietly conducted the first steps of the program last year, when it hired a consultant, a Manhattan-based firm called RBA Group, to evaluate each of the 1,400 middle and elementary schools in the city. It’s a $1.9 million contract.

RBA developed a formula, which, assigning different weights to various types of car accidents, calculates the acuteness of the problem in a 700-foot radius around each school.

The formula helped identify 25 schools in the Bronx, 46 in Brooklyn, 23 in Manhattan, 33 in Queens, and eight in Staten Island. The schools range from public schools such as P.S. 96 on Rockaway Boulevard in Queens, to religious schools like Yeshiva Shaare Torah on Ocean Parkway in Brooklyn, to elite private schools like the Collegiate School on the Upper West Side.

Next, the consultants mapped the areas around the 135 most dangerous school buildings and met with principals, parents, local police precincts, crossing guards, and community boards at each school to talk about remedies.

The deputy commissioner for sidewalk and inspection management, Leon Heyward, said that before the school year started, his crews recemented sidewalks, rebuilt curbs, and created “ped ramps” at the corners at all 135 schools. Some of the work cleared up so-called “trip hazards.” Some jobs fixed more dangerous situations.

At one Bronx school, for example, children had to walk in the street because the area beside their school was overgrown with weeds and puddles of still water. Mr. Heyward’s staff created a safer walkway.

In the next six months, the more difficult engineering and construction work gets under way.

Mr. Soffian and Mr. Woloch said new stop signs and traffic lights would be installed. New crosswalks would be painted. Downward pointing arrows would also be painted at intersections.

Traffic will be slowed down with speed bumps or “neckdowns,” blocks of cement that narrow roadways. Geometry of roadways will be shifted, so that roads meet at right angles rather than the combinations of acute and obtuse angles that encourage cars to speed around bends. At wide roadways, raised medians will be built where students cross.

Outside P.S. 1, parents praised the new initiative, though they said they didn’t understand how city officials would make Chinatown traffic safer.

“It’s very high traffic and commotion right here,” said William Wong, father of a 3-year-old preschool student. “People double-park and don’t know where they’re going.”