“You can’t imagine how loud it was,” he said. ““It’s a residential neighbourhood. I can’t imagine the people with little babies or toddlers. It was terrifying.”

Dahlia Clark said the horn was keeping her family from sleeping, sounding every few minutes as it crossed the tracks.

“No sleep, it’s torture,” she said.

“These people sitting in their offices at CN, they don’t realize what it’s actually like to go through that, night after night. We can’t function.”

Nearby residents have taken to social media to organize themselves and send the message that the whistle needs to stop.

At press deadline on Tuesday, CN provided a statement apologizing to residents for the "inconveniences and frustrations" caused by the recent work.

"As a result of the feedback from the community received, CN will be taking immediate action to mitigate the impact on local residents," the statement reads.

"Effective immediately, CN will provide manual safety measures at crossings while operations continue during evening hours. This will stop the need to use whistles during the night. This measure will be in place until new operating hours can be implemented."

CN Update. Tonight there will be no whistle or horns as @CNRailway works out a long term solution. I’ve asked @CNRailway to call @CamGuthrie and @PhilAlltWard3 to continue working out solutions. pic.twitter.com/hzSaAeD0u4 — Lloyd Longfield (@LloydLongfield) June 4, 2019

It's not yet clear why train operators were sounding the whistle overnight. Ward 3 councillor Phil Allt said he's been reaching out and has received a number of explanations.

“What we know as fact is they’re blowing the horn, they’re keeping the neighbours up, and we’re getting all sorts of explanations for why that is,” he said. “You ask a different spokesperson, you get a different reason.”

Officials from the City of Guelph and Guelph Junction Railway held a phone meeting with CN Rail on Tuesday. Amber Bryer, administrative assistant with GJR said the whistle blowing may have been an oversight by CN train operators.

The city has a bylaw from 1983 that lists specific crossings in the city where train operators are not to sound the horns, she said. The meeting was to discuss the validity of this bylaw, as many changes to it have been made over the years, she said.

“In a no whistle zone they may still be able to blow a whistle in case of an emergency, which of course none of this activity would fall under emergency, except when people are protesting on the tracks,” she said.

Midway through their meeting on Tuesday, she said CN promised not to whistle overnight, unless people were seen on the track.

Before CN made this announcement, Simon and others had said if residents were woken by train whistles in the coming days, they would be back out to protest.

“If they blow the horn, we will be out en masse,” he said.