Every child who rides a school bus in this state is entitled to have 13 inches of seating space.

	Steve Mellon, Post-Gazette Bus driver Pat Kincaid -- "I'm trying to be safe about it for the welfare of the kids." Click photo for larger image. Related article No charges in school bus audiotaping

The problem is, many students, especially those in middle and high school, need more room for themselves and their belongings.

"A whole lot of rumps are larger than 13 inches," said Ted Vasser, director of transportation for Pittsburgh Public Schools. "We have to be careful not to overload our buses."

The issue of whether some school buses are overcrowded came to the forefront recently when Patrick Kincaid, a school bus driver for Laidlaw Education Services, claimed he was pressured to drive an overcrowded bus load of West Mifflin Area Middle School students on a school field trip to Downtown.

Bus overcrowding is a challenge for school districts across the nation because school transportation budgets are being cut or staying the same while the cost of transportation is dramatically increasing.

State education officials don't have numbers on how often school buses in Pennsylvania carry too many passengers, but districts that want to be reimbursed for some transportation costs are required to show its buses are being used to the highest capacity.

Bus manufacturers, not the federal government, specify the maximum number of students that can safely ride on a school bus.

Mr. Kincaid was suspended for half a day without pay after he complained about too many students being on the bus he was driving.

"I'm trying to be safe about it for the welfare of the kids," said Mr. Kincaid. "But when I contacted dispatch to try to solve the problem, they told me, 'You have a 72-passenger bus and you're going to haul 72 passengers.' "

After arriving at their destination, the Byham Theater, Mr. Kincaid said, "I did a head count and found that we actually had 147 people on the two buses and eight were full-sized adults."

Dave Armitt, vice president and general manager in Laidlaw's New Jersey office, said the company's policy requires drivers to call dispatch and request another bus if there are too many students.

"We do not condone overcrowding on buses," Mr. Armitt said, adding that Laidlaw has about 1,000 school contracts in the United States and Canada. "In this case, the school asked for two buses. We sent two buses. But they should have asked for three."

Frank Prazenica Jr., superintendent of West Mifflin Area School District, declined to comment.

Overcrowding is most likely to occur during field trips when school districts underestimate the amount of space needed or during the beginning of a new school year when the district is still unsure how many buses it needs for some routes.

"If it's a 72-passenger bus, typically school districts will schedule 72 elementary students on there so they don't have to spend more on another bus," Mr. Armitt said. "With bigger kids, they recognize it might be a little more difficult to get three on a seat so they use some discretion there."

Overcrowding "happens occasionally," Mr. Armitt said. "When it does happen, I think it's human error, an honest mistake. I don't think there's any intention to create an unsafe situation. We do have a policy to prevent this from happening."

School districts keep a close eye on transportation costs because it is among the most expensive line items in the budget.

Pittsburgh Public Schools will pay $25 million to 14 school bus contractors this year.

"When we look at middle school kids, we find that some of them are just as big as high schoolers," Mr. Vasser said. "But when it comes to elementary kids, we try to maximize three to a seat as best we can because we get reimbursed by the state for transportation and one of the main components of the reimbursement is how full the bus is."

In the event of a crash or sudden driving maneuver, students who are not properly seated within the seat compartment, could have a greater risk of being injured.

Four school-aged children died in bus accidents last year compared with 42,600 automobile fatalities, according to the National Highway Traffic Safety Administration.

State law requires that seating space be provided for each passenger. A passenger may not be carried if a safe designated seat isn't available. School bus drivers can be cited for overcrowding.

Mr. Kincaid said he complained because a similar dispute had happened in the past and the company did not support him.

"Drivers are very cognizant of overcrowding because if they get stopped, they'll be penalized for it," said Rick Marsh, director of transportation for Woodland Hills School District, which will spend nearly $6 million this year on transportation.