For years, the New York City Transportation Department has held a trump card in the roiling debate over its many roadway interventions: When officials said the measures, like pedestrian plazas and bike lanes, had made streets safer, the numbers appeared to back them up.

But the release last week of the Mayor’s Management Report, a twice-yearly collection of city measures, revealed a disquieting figure. Traffic fatalities from July 2011 through June 2012 were up 23 percent from the previous year — to 291, from 236. It was the first increase since 2007, when there were 310 traffic fatalities.

Though overall crashes fell slightly for the second straight year, 176 cyclists or pedestrians were killed in crashes, up from 158 the previous year. The other 115 deaths were motorists or their passengers, a sharp rise from the 78 drivers and passengers killed the year before.

The Transportation Department typically compiles figures for the calendar year, Commissioner Janette Sadik-Khan said, so the agency wanted “to reconcile what’s going on.” She allowed, however, that “it does look like there’s a rise.”