The transit union says 18 fewer buses are on the road for the holiday weekend, a result of the new city-imposed scheduling system for OC Transpo drivers.

The schedule took effect last month, and the transit union says shifts aren't being filled, which is affecting service and driver morale. Scheduling was also the main reason for the 53-day transit strike.

"A lot of guys are refusing overtime because of their frustration, and a way to show their frustration is to stop working overtime," said Mike Aldrich, the transit union vice president.

The union says 10 buses were taken off the road because there weren't any drivers to work them.

There are also drivers who can't work because they have worked all their allotted time.

OC Transpo refused an interview because they do not discuss internal matters.

In a memo to city council three months ago, OC Transpo General Manager Alain Mercier says the new booking process will save the City of Ottawa money and efficiency.

With a report from CTV Ottawa's Vanessa Lee