Mary Beth Ellis misses her daughter, Sidney Mae Olson, a young girl who found joy in the small things: flowers, rainbows, books, art, and being an active part of the community.

Ellis remembers Sidney picking out the “perfect flower” to bring to her father’s desk on May 8, 2023. Just a day later, Sidney died at age 5 when the driver of a tractor-trailer struck and killed the girl, who had a full life ahead of her, at a busy downtown intersection in Andover.

Sidney and a family member had been crossing a crosswalk on their way to art class, and the walk sign showed that it was still safe to cross.

Friday marked two years since the tragedy, and Ellis will celebrate her second Mother’s Day without Sidney on Sunday. She and her husband, Eric Olson, are on a mission to honor their daughter’s legacy.

“The hardest for me is that every day takes us further away from the days with Sid. It is so bittersweet,” Ellis told the Herald on Saturday, at an Andover recreation complex where she and her husband hope will someday feature a bike park in Sidney’s name with a kid-friendly pump track and mountain bike skills area, in partnership with the town.

“As a parent, I still love to talk about her,” Ellis added, “bring up the good memories, think about all of the fun times we had together as a family.”

The 47-year-old mother, a former professional endurance athlete who ranked among the world’s best in the Ironman, pointed out how she and her husband have set up a free library in front of their home in Sidney’s honor.

Their efforts in carrying out their daughter’s active and community-focused spirit have been far-reaching through “Sidney’s Rainbows,” a fund that promotes their work.

Ellis and her husband are continuing a campaign dubbed “Freedom to Move,” which has two sides: advocating for technology that makes roads and vehicles safer for all people and opening access to safe activities for children.

“What we have learned along the way is that the technologies that could have saved Sid’s life and can save a lot more lives, and create safer communities, exist,” Eric Olson told the Herald.

Immediate advocacy efforts led to a slew of road safety improvements in the Merrimack Valley town, including changing the traffic signals at the intersection where Sidney was killed to an “exclusive pedestrian phase.”

That means traffic is stopped in all directions when the walk signs are on. At the time of the tragedy, vehicles were allowed to turn across a crosswalk while a walk sign was showing.

Olson traveled to Washington, D.C. last May for an advocacy event with the National Safety Council, pushing for policies and measures to make roadways across the nation safer. The opportunity, he said, opened his eyes to how technology is the “only way” to change roadway behavior.

Olson is closely following legislation that Gov. Maura Healey included in her budget proposal for fiscal year 2026, which contains provisions to legalize the use of automated speed enforcement cameras across Massachusetts. He said the equipment in other states has decreased fatalities.

An investigation into the crash that killed Sidney found the driver not at fault, Essex County District Attorney Paul Tucker announced in November 2023.

The driver did not face any criminal charges. The investigation found that the driver stopped at the intersection and did not see Sidney traveling on her scooter in the crosswalk below.

Sidney’s Rainbows is also partnering with the national group, Families for Safe Streets, in creating a state chapter that would provide resources and the opportunity for families affected by roadway tragedies to advocate for safer streets.

Ellis, the fund’s executive director, continues to lead Sidney’s Rainbow Runners, a program inspired by her daughter’s “love of running and the outdoors.” Kids ages 5-13 have discovered their own passion for the things that made Sidney smile, her parents said.

This summer, the fund is hosting track races for all community members

Eric Olson remembers the day before Sidney’s death when his daughter was excited to release butterflies that her class had been hatching.

“She’d come home from school,” he recounted of Sidney, “and she had this little phrase she’d say ‘You will think this is crazy, but,’ and it was always these little things like the butterflies hatched.”

As the husband and wife reflected on their daughter’s life and carrying out her legacy, their 4-year-old son Ellis played in the rain, splashing into puddles, finding joy in the small things, just like his older sister did.

“One of my fondest memories is that we would be in our room across the hall, just hearing them talk after we put them to be,” Mary Beth Ellis said. “There’s nothing like watching your kids bond and play.”

“She’s still a part of our lives,” the mother added, “and I think forever, she’s going to be a huge part of our lives.”

Sidney Mae Olson died after a driver of a tractor-trailer hit and killed her in a downtown Andover crosswalk. The 5-year-old girl was on her way to art class with her family. (Courtesy/Olson family)
Sidney Mae Olson on her fifth birthday. (Courtesy/Olson family)