LAC-MEGANTIC, Que. -- Four years after the rail disaster that killed 47 people in their town, a group of Lac-Megantic citizens renewed the call for the construction of a bypass that would steer trains away from the core of the community.

Robert Bellefleur, spokesman for a rail-safety group in the town, said Thursday his group is outraged that Prime Minister Justin Trudeau and other politicians seem to accept that a bypass might not be ready for years.

"What shocks the population, it's to note that it's politically acceptable...to wait until 2022 for a safer solution for Lac-Megantic," he told a news conference.

The Quebec and federal governments have financed a feasibility study on the matter, and the province's environmental review agency began public hearings on the issue in May.

But Bellefleur said dangerous goods continue to be transported through the town on a section of rail track that has been rebuilt with an even steeper curve than before.

"What we want, the citizens' coalition, is that we build the bypass as quickly as possible," he said.

"We want an announcement this summer, and while we're waiting for it to be built, we want them to fix this death curve."

On July 6, 2013, a runaway train carrying crude oil from the United States derailed in downtown Lac-Megantic and exploded, killing 47 people and destroying much of the city's core.

To mark the anniversary, the town planned a series of low-key activities including a church service, an outdoor vigil and an activity at the town's train station.

The disaster led to hundreds of millions of dollars in clean-up and reconstruction costs as well as the bankruptcy of Montreal, Maine and Atlantic Railway, the company that owned and operated the tracks.

to say "no community should ever experience what Lac-Megantic went through."

"I am committed to ensuring that rail safety remains a top priority," he said.

But while policy-makers continue to look for ways to improve rail safety, Lac-Megantic is well into the reconstruction process.

Sonia Dumont, a spokeswoman for the town's rebuilding committee, says construction on several new projects, including a new park, pedestrian walkway and multi-functional community space, will begin this fall.

The town is also developing new "human infrastructure," including a new greeters program where citizens act as guides for tourists.

Meanwhile, three ex-railway employees are awaiting trial after pleading not guilty to 47 counts of criminal negligence causing death stemming from the tragedy.

Their trial is to be held in Sherbrooke instead of Lac-Megantic and is set to last from Sept. 11 to Dec. 21.

Conviction on a charge of criminal negligence causing death carries a maximum penalty of life in prison.

Montreal Maine and Atlantic Railway was charged with the three men and has pleaded not guilty to similar charges.

It will face a separate trial at a later date.