In a hurry to get to downtown Los Angeles from Hollywood on public transit? Hop on the Metro's Red Line trains, which depart from stations on schedule 99.5 percent of the time.

Don't mind showing up late? Wait for the 2 bus, which pulls away from stops at least five minutes late nearly a quarter of the time.

A KPCC analysis of data covering more than 74 million trips over the last five years shows some bus lines - including some of the most popular - are chronically late. Other buses regularly stick to their schedules, but none did as well as Metro’s rail lines.

One-fifth of the Los Angeles Metropolitan Transportation Agency's buses close their doors late. And the reason may be the same one you give your boss some mornings as you sheepishly walk to your cubicle: traffic.

"Our buses are subjected to the same traffic congestion as everyone else," said Rick Jager, a spokesman for the MTA.

Mostly on time

The good news is that most of the buses serving the county's 170 lines arrive on time or early - 80.6 percent do. But Metro's definition of "on time" may surprise riders: buses can depart four minutes and 59 seconds late and still be considered "on time". Buses aren't considered late until they're 5 minutes behind schedule.

And that's still worse than Orange County. About 87 percent of buses arrive to stops on-time there, according to figures from the Orange County Transportation Authority. The agency also defines "on time" as less than five minutes behind schedule. But it ferries far fewer passengers on about 100 fewer routes.

Metro surveyed other big-city transit systems in 2008, and found its buses were the least punctual of any agency surveyed, including systems in Chicago, New York and Seattle.

Metro's on-time performance improved 0.7 percent between 2010 to 2014, according to its own data. That may not seem like much, but applied to millions of stops each year, it can mean more than a hundred thousand doors opening on time.

Best and worst

The best performing bus in Los Angeles County: the 901, better known as the Orange line, which shuttles commuters 20 miles from Chatsworth to North Hollywood right on time 94 percent of the time. It's the only bus route with a dedicated lane.

On the other side of the spectrum, the 205 bus — which traces a 29-mile route along Western, Vermont and Wilmington from San Pedro to Willowbrook — is late 30 percent of the time. That's the worst performance of any bus with a healthy number of stops.

Metro's five best and worst bus lines for on-time performance. These buses all had over 250,000 stops recorded in Metro's data.

Some months are better than others for riding the bus.

The data show less than a fifth of Metro buses were late in July (17.5 percent late) and January (18 percent). The numbers for October (22.1 percent late) and September (21.9 percent) are considerably worse.

"When the schools start up in September, October, more parents are actually driving their kids to schools," Jager said. "So our buses are having a harder time getting though."

About five percent of buses arrive early. When they do, they're instructed to wait at the stop until the scheduled time, according to Giancarlo Restreppo, of the agency's records management center.

A few notable facts:

The 460, Metro's longest route covering 40 miles, was late 25.4 percent of the time. It goes from Downtown Los Angeles to Disneyland.

The 220, Metro's shortest route, was late 22.5 percent of the time. The line runs along Robertson Boulevard from West Hollywood to Culver City.

The 720, Metro's most-boarded route, left stops late 30 percent of the time. The line runs from Santa Monica to Commerce, and it’s one of the worst-performing routes in the system.

Two buses zip along the highways in lanes that aren't bus-only. The Silver Line uses express lanes on its route from El Monte to Torrance, and stays timely (17.6 percent late). The 577 uses HOV lanes on trips from El Monte to Long Beach, but still arrives late 18.7 percent of the time.

On the tracks, on time

Metro's trains, on the other hand, glide into stations on time nearly all the time. Since December 2009, more than 99 percent of trains departed on schedule.

Some lines are more punctual than others. The Red and Purple Lines zip along underground, arriving late only once in 200 stops (the lines are tracked together). Those lines run entirely underground and are served by heavy rail trains, unlike the rest of the system.

The light rail Blue Line trains are four times more likely to show up late. About 1 in 50 of them did during the five year year period, the worst performance in the rail system.

The 21-mile line has more street-grade crossings than other Metro rail lines, said Restreppo. Street-grade crossings make lines more susceptible to street traffic.

The Blue Line was the first in L.A. County's modern rail system, opening in 1990.

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Tracking transit

The data, provided by Metro in response to a Public Records Act request, tallies 74,425,377 stops by its buses and trains across Los Angeles County, from December 2009 to November 2014.

In recent years, the Metro has outfitted buses with equipment that tracks when and where they open and shut their doors. Each night, that data is downloaded from buses and matched to bus schedules to determine how many departed early, on-time and late.

The system ignores buses that were more than 20 minutes early or more than an hour late, and the first and last stops are also ignored.

Data collection works differently for rail. When a train arrives more than five minutes late, or is cancelled, an employee at the Rail Operations Control Center makes a record, which eventually gets entered into an electronic database.

"We may miss logging one or two delays, but it’s a rare occurrence," Restreppo said.

Richard Anderson, who studies transit at Imperial College London, said some public transit systems have moved towards "passenger delay metrics", which gauge the effect of transit service on riders. Buses that are late but fairly regular may not inconvenience riders, the thinking goes.

Metro doesn't track such metrics, according to Restreppo.

This story is part of Transportation Nation, a public radio reporting project that combines the work of multiple newsrooms to provide coverage of how we build, rebuild and get around the nation. To read other Transportation Nation stories, click here. Let us know what you think in the comments below, on KPCC's Facebook page or on Twitter (@KPCC).