Take 240 school buses and divide them among about 720 routes to get 22,000 students to and from 34 schools. On time.
It's always a challenge, but drivers additionally encounter surprises during the first few weeks of school -- such as more students at some stops and fewer at others than they expect.
"I used to use the analogy that it's like a Rubik's Cube," said transportation assistant David Reeve. "But all the sides are the same color."
It happens every year, Mr. Reeve said. Carroll County is growing at a rate of about 700 students a year, and school officials say that several new families wait until the first day of school to register their children.
One bus to Westminster Elementary School showed up at a stop in a new development and found many more students than could fit into the bus, he said. Several parents who were there waiting with their children offered to drive them to and from school the first two days. By the third day, an additional bus was assigned to the route, Mr. Reeve said.
"The parents helped us out a lot," he said.
Because the school buses will pick up and drop off children at their day care homes, first-week confusion increases, Mr. Reeve said. "We have a pretty good idea of where the children live, but where they get on and off the bus creates some overcrowding situations," he said.
Mr. Reeve said the staff fixed severe overcrowding on buses in the first week, but waited to deal with less serious cases until after drivers submitted the first four days of detailed reports on the number of students at each stop and on buses.
Meanwhile, schools are keeping track of when buses arrive and whether students have enough time to get to their lockers and classrooms before the bells ring. Because some elementary schools dismiss students as late as 3:45 p.m., he said, some buses will be on the road until 4:30 p.m. and a few until 4:45 p.m.
School starting times are staggered because some buses serve as many as 200 students on four different routes. This rural-suburban county has a high proportion of students who ride a bus, either because they live more than a mile from school or because there is no safe walking route.
Of Carroll's 25,000 students, about 22,000 ride a bus. Even more are eligible, but they choose to drive or are transported by their parents.
"Most of the overcrowding problems should be taken care of by the end of next week," Mr. Reeve said. "By the end of September, we want to have all the overcrowding and all the scheduling problems worked out. Then we look at individual requests for additional bus stops and newer communities requesting bus service in their neighborhoods.
"And you know what? After Christmas, we'll have to do this all over again," he said. "Some of the people moving into the community use the holidays as a time to move their families. Then certain places where we had 10 children waiting for the bus, first day after the winter holidays, there are 25.
"You know it's going to happen, you just don't know where," he said.