One year ago, when one hour of sleep a night was all Mark Mayr could manage in his grief, he set a goal: "I've got to make it through a year."

Eventually, sleep returned. But last week, as the first anniversary of his daughter Rose Mayr's death in a train derailment in the heart of Ellicott City approached, reminders were everywhere and the sleepless nights returned. "I felt myself slipping," he said.

For Eric Nass, whose daughter Elizabeth "Liz" Nass died alongside Rose Mayr when the coal train left its tracks, the anniversary also weighed heavily on his thoughts — the only comfort being that there would never again be a first Christmas without Liz, or a first birthday.

"At least the year of firsts will finally be over," he thought.

A federal investigation is still under way into the Aug. 20 accident that not only killed the two 19-year-old women but shut down the town for days and rattled its residents. A National Transportation Safety Board official said Tuesday that the organization is investigating the accident "vigorously" because it highlights the "increasing danger of non-passengers being near railroad tracks."

Non-passenger deaths have become more common than all other railroad-related deaths. A total of 843 people were killed or injured near railroad tracks in 2012, an 8 percent increase over 2011, and 356 have been killed so far this year, Robert Hall, director of the NTSB's office of railroad, pipeline and hazardous materials investigations, wrote in a blog post Tuesday.

Hall mentioned Mayr and Nass, though not by name, saying the two college students were apparently "texting and chatting" on the bridge when the accident occurred.

"While their intent seems innocent, their actions broke the law, since railroad tracks are private property," Hall wrote. "It also placed them in grave danger."

Rose's and Liz's parents said they have been told nothing about the investigation. "To my mind, the answer's not going to change the things we have to live through, but we want to know what happened," Mark said.

For the two sets of parents, the last year has been a challenge met one day at a time.

Bursts of laughter will come to Sue Nass and Sharon Mayr when they remember their daughters' antics while dancing at Mount Hebron High School together, but tears can be quick to surface, too.

Mark can look on Rose's high school and college pictures fondly, but images from her childhood trigger too much emotion. At his parents' home in Cape Cod earlier this summer, Eric remembered some of his fondest memories with Liz but anguished over her absence.

Through it all, though, the grieving parents said they have been buoyed by the compassion of others: family and friends, neighbors and strangers. New connections, such as those with their daughters' college friends whom they hadn't met — Rose attended the University of Delaware and Liz James Madison University — have given them new windows into their daughters' lives.

Community support also has been critical in the lead up to the anniversary of their daughters' deaths, which they consider to be Wednesday — the train derailed around midnight, killing the teens through compressional asphyxia.

When about 600 people descended on Ellicott City to honor Rose and Liz with a memorial run this past weekend, and two benches were dedicated in their honor in the town's tiny Tiber Park, anxiety over the anniversary eased, they said.

"When the sun was shining and the weather was like no other August in Maryland I can remember, it was like it was meant to be," Sharon said. "After the race I feel like I came to a turning point, where I want to go on more than I did before. I'm better equipped."

"For me it was something positive to focus on, instead of our loss," Sue said.

"Instead of a big black hole," said Sharon.

NTSB officials have released no new details as to the cause of the derailment since a preliminary report 10 days after the CSX Transportation train leaped off its tracks. A final report is pending, as investigations into derailments often taken as long as 18 months.

The train was traveling at its designated 25 mph speed for the area, and its emergency brakes had engaged automatically as the result of a rupture in a pressurized air brake line, but what caused the rupture is unknown, officials have said. The three crew members on the train told investigators that they "felt nothing and saw nothing before emergency braking occurred."