Metro failed again to meet its goal for how many of its buses were on time in 2012, while the transit agency met its recently lowered standard for rail performance, according to a report released Monday.

Only 76.3 percent of Metrobuses arrived on time in 2012, falling short of the agency's goal of 78 percent -- a target that was lowered from 80 percent in 2011.

"It has a lot to do with traffic congestion," said Metro spokesman Dan Stessel. "D.C. being among the top worst regions for traffic congestion makes it difficult to keep buses on time, which has been the case for many years, and a challenge for us."

But the buses last year were more consistent than in 2011, when only 75.3 percent were on time.

Category 2011 2012 Old target New target
Rail on-time performance 90.1% 91.0% 95% 90%
Bus on-time performance 75.3% 76.3% 80% 78%
Escalator availability 85.5% 89.3% 93% 89%
Elevator availability 96.3% 97% 97.5% 97.5%

Metro trumpeted its improvement in recent years, saying buses improved on-time performance by 3 percent since 2010. But Metro's definition of "on time" means that a bus can be two minutes early or seven minutes late and still be counted as arriving on time.

Metro trains were on time 91 percent of the time, exceeding the agency's target of 90 percent. But that target was also lowered in 2011, from 95 percent.

When Metro lowered its goals for bus, rail and escalators in 2011, General Manager Richard Sarles defended the lower bar, saying it would help staff focus on making improvements and was "a good way of managing."

The Red Line was the worst offender in 2012 -- trains arrived on time only 89.6 percent of the time. The Green Line was the best, with 92.8 percent of trains on time.

Metro credited less midday trackwork as one reason that 2012 beat 2011's performance, when only 90.1 percent of trains were on time.

The transit agency said it improved the reliability of its railcars, which broke down less often in 2012. But the railcars still only traveled 46,274 miles between causing a delay of more than three minutes in 2012, falling short of the agency's target of 60,000 miles between delays for each car.

And Metro again failed to meet its standards for having elevators available, with elevators available 97 percent of the time, instead of the goal of 97.5 percent. But it improved over 2011, when elevators were available 96.3 percent of the time.

Escalators were also available more than in 2011, by nearly 4 percent -- up from 85.5 percent in 2011 to 89.3 percent in 2012.

Metro attributed the change to better escalator maintenance, saying it hired 18 additional mechanics in 2012. Metro also finished installing new escalators at Foggy Bottom and Dupont Circle last year.