Perhaps the most surprising finding was that excessive weight may prove a boon for pedestrians in a collision. 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. Frangos noted that generally, 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.”

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, the 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 in the future.”

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 less than a third wore helmets.

Administration officials said the report reinforced many of their own findings, including the need for bike lanes, pedestrian plazas and other traffic-calming measures. Traffic fatality rates have fallen sharply under the Bloomberg administration, though the 274 traffic deaths in 2012 were the most in four years.