The City of Ottawa is apologizing after a jammed door on one of its new LRT trains caused a domino effect which led to massive backups at stations up and down the Confederation Line on Tuesday morning, the second day of full operation for the city's integrated transit system."I'd like to start off and give an apology to our customers that experienced a delay this morning," said John Manconi, the city's general manager of transportation services, at a news conference Tuesday afternoon.The delay was caused by a single jammed door on a train stopped at uOttawa station at about 8:05 a.m., Manconi said. A door on the train became stuck after a passenger held it open while exiting."With a door in a jam position the train could not move," said Manconi. Technicians attempted but failed to close and lock it.The problem train, which ultimately had to be removed from the tracks, caused the entire light-rail system to slow down, stranding commuters who continued piling off buses on platforms and concourses at either end of the line for more for up to an hour."As the buses continued to drop off passengers, the crowd really began to balloon in size quite quickly," said Jon MacIndoe, a commuter travelling from Nepean to downtown Ottawa on Tuesday morning. His trip ground to a halt at Tunney's Pasture at around 8:30 a.m."Both of the tracks were completely full of people. The stairwells were filling up with people. As I made my way outside, the platform on the ground level was also full of people. Certainly hundreds, perhaps into the thousands," he said.After watching two buses pass by full of people, MacIndoe grabbed a cab to avoid being late for work.On social media, other passengers complained the LRT platforms were so crammed that waiting lines bottlenecked at escalators and poured out station doors. By 9 a.m., OC Transpo announced service had resumed, but "delays continue until platforms are cleared." It took until 9:16 a.m. before all residual passengers cleared the platforms and the LRT system returned to normal, said Manconi. Throughout the morning, trains had been able to travel along the Confederation Line, only with less frequency."It's not one door taking down the whole system," Manconi said. The incident served as a reminder that a single malfunction can back up the entire east-west system, and that the train doors continue to cause problems.Manconi offered five "friendly reminders" for passengers to help OC Transpo avoid a door jam from happening again: 1. Use all 14 available doors for entering and exiting the train. 2. Don't hold open the train doors. 3. Avoid gathering around the doors on platforms. 4. Get ready to exit the train before your stop. 5. Let fellow passengers exit before trying to get on the train.OC Transpo is also looking at customizing the length of time doors stay open, depending on which station they are stopped at, said Manconi.While passengers also complained about overcrowding on Monday morning, the first commute without a parallel downtown bus service went relatively smoothly compared to Tuesday morning.