NEW YORK – Pedestrians are struck most often by cars while in the crosswalk, with the signal on their side.

Taxicabs pose a disproportionate threat to cyclists, who often compete for the same sliver of curbside roadway.

And for those who do get hit, an unexpected factor may protect against serious injury: being overweight.

These are among the findings of a medical study of injured pedestrians and cyclists in New York, conducted by a team of trauma surgeons, emergency physicians and researchers from NYU Langone Medical Center.

From December 2008 to June 2011, the group studied more than 1,400 pedestrians and cyclists treated at Bellevue Hospital Center after collisions. Most occurred in Manhattan and western Brooklyn, stretching along the busiest corridors of a city where street safety and traffic engineering have been trumpeted as defining legacies of Mayor Michael R. Bloomberg’s tenure.

Perhaps the report’s most surprising finding was that excessive weight may prove a boon for injured pedestrians.

Victims with an above-normal body mass index were found to have less severe injuries than their counterparts. “It is not implausible that a greater proportion of torso and extremity fat may protect against injury,” the report said.

Dr. Spiros G. Frangos, the study’s senior author, noted that overweight and obese patients fared worse once admitted to a hospital, but that perhaps “that extra layer offers some protection at the time of the injury.”

The study could help inform transportation planning in the city, as administration officials – with whom the authors corresponded throughout their research – evaluate how best to engineer the streets to reduce the types of injuries suffered in these cases.

Many of the results, published in the Journal of Trauma and Acute Care Surgery, reinforce common intuitions about the city’s traffic flow. Others seem to defy conventional wisdom. But all combine to demonstrate how personal habits and choices – like listening to music, wearing a bicycle helmet or hailing a cab – can change a life.

“Undoubtedly, behaviours can be improved across the three major parties: pedestrians, cyclists and drivers,” Frangos said in an interview.

While some studies, including a 2010 city Transportation Department report on pedestrian safety, have focused on the frequency, location and timing of accidents, the Bellevue report has focused on the patients themselves. Data was obtained through victim self-reporting shortly after a collision, combined with medical records and accounts from witnesses and first responders.

In some cases, it seemed, the awareness level of the pedestrian or cyclist may have been compromised. Among patients 18 and older, 15 percent of pedestrians and 11 percent of cyclists were found to have consumed alcohol before the collision – a figure that stood out to transportation officials whose focus is often reckless driving.

“Obviously it’s better for people to be walking than driving,” Matthew Roe, a senior planning and research manager for the Transportation Department’s Division of Traffic and Planning, said of the city’s intoxicated travelers. “But it’s something probably worth thinking about.”

About 8 percent of both pedestrians and cyclists said they were injured while using an electronic device, including a cellphone or music player. For victims ages 7 to 17, the numbers climbed to more than 10 percent of pedestrians and nearly 30 percent of cyclists.

In a finding unlikely to surprise the city’s cyclists, about 40 percent of injured riders were hit by taxis, compared with 25 percent of the pedestrians. More than 80 percent of cyclists rode with traffic flow, but fewer than a third wore helmets.

