Thousands of construction workers rallied outside of City Hall on Thursday, displaying a row of eight black coffins and demanding the city enforce stricter safety measures at construction sites.

As the death toll at New York City construction sites surged over the past few years -- 18 construction workers perished during the last fiscal year, up from 12 the previous year and seven the year before that -- fears have heightened.

Many marchers claimed non-union workers posed greater risks at construction sites because they do not go through the same stringent safety requirements as their union counterparts. "We need proper training for all construction workers," said Phillip Cammock, 59, a construction worker from New Jersey.

Most union members are required to attend a safety orientation before they can step onto a construction site. Benjamin Braham, a 55-year-old plumber from Bedford-Stuyvesant, said the orientation helped him keep safe while working on hazardous projects. "You should always want to be safe," Braham said.

A report by the Occupational Safety & Health Administration found that from 2012 to '13, 72% of fatal fall construction accidents in New York City occurred on non-union worksites.

Most accidents occur on sites where workers and developers and not following construction codes, according to a spokesman for the New York City Department of Buildings, but he could not confirm whether accidents are more common at non-union sites because the city does not record whether a site utilizes union workers. The DOB is stepping up discipline for violators, according to the spokesman.

"It's not just a matter of issuing a fine for a violation, we're very aggressively going after contractors' licenses, especially those who are habitually breaking construction codes," he said.

Councilman Corey Johnson announced plans to introduce legislation with Manhattan Borough President Gale Brewer to require construction workers to complete a safety instruction program before working on buildings that are 10 stories or taller.