If you're taking a bus to your morning meeting, you might want to leave home earlier than usual.

OC Transpo's new report on their January to June on-time performance shows one in five buses is late during morning rush hour — the worst performance OC Transpo has reported in the seven years it's been making those records public.

Also, almost one quarter of routes throughout the day arrive early, leaving Ottawa-Gatineau commuters unsure of when to arrive at their stop to catch a ride.

"The biggest thing that affects whether a bus comes on time or not is the circumstances in which we're operating, which is almost always automobile traffic," said Pat Scrimgeour, the city's director of transit customer systems and planning.

"Sometimes it's just volume of traffic. Sometimes it's external events."

Light rail work to blame

One external event that's caused an increase in OC Transpo delays, Scrimgeour said, is the construction on the LRT's Confederation Line.

Until the line opens next year, Scrimgeour said the plan is to keep doing what they've done thus far. Once construction is finished, he anticipated many delays would cease.

The agency releases the numbers twice a year, measuring on-time performance during the 6 a.m. to 9 a.m. morning rush as well as regular routes throughout the day.

Those latter routes fare a little better, with only 13 per cent of buses coming late — a marked improvement from last year's 18 per cent.

Still, with the transit service averaging 320,000 riders on a given weekday, the data suggests some 40,000 people arrive at their destinations late every day.

OC Transpo's goal is to have 90 per cent of buses arrive on time, according to their website.

Their reports, however, show the on-time rate hasn't exceeded 70 per cent in the last seven years for which records are available.

"A bus that comes [so late] that it appears to have not come at all is a big problem," Scrimgeour said.