Barely an inch or 2 of snow Tuesday morning in the largest metropolitan area in the Upper Midwest brought to a frustratingly slow crawl a transit bus system that serves on average 270,000 or more commuters every weekday.

Metro Transit needed just two words to explain why: Timing and demand.

From almost the moment the buses started snaking along highways, thoroughfares and residential streets, the pace of bus service worsened until well after 9 a.m., considered roughly the end of a weekday's morning commute.

By 9:30 a.m., roughly two-thirds of all buses on their routes were running late. The average steadily and relentlessly grew longer, topping out at an almost unheard-of 24 minutes before shrinking again throughout the morning.

Metro Transit declared at 1 p.m. on Twitter that "the bus system has stabilized & delays are now minimal. We will continue to monitor. Thanks for your patience today."

Patience, indeed.

On one popular bus route that slices up Lyndale Avenue in south Minneapolis, some frustrated riders were getting off well before their usual jumping-off point and hoofing it the rest of the way to their destination.

One rider on that route, the No. 4, boarded at Lake Street and Lyndale and had yet to make it even 10 blocks after an hour. Her usual 20-minute bus ride downtown lasted nearly 1½ hours.

Sean Johns, of Minneapolis, was hoping to make it to work downtown at the IDS Center by 9 a.m., but he gave up checking his watch and passed the time shaking his head.

"It's not the first snow, so I don't get it," said Johns, a cook at People's Organic, who has been riding the No. 4 to work for more than a year and never before endured such a delay.

Tuesday morning's slog was doomed, said Metro Transit spokesman Howie Padilla, because "the weather and road conditions upon which we rely were far from ideal with an event that started early this morning and stretched for hours into the afternoon."

Padilla added that if ridership figures from previous snowfalls are any indication, there are more riders who "don't want to take to the streets themselves."

Quite simply, it takes longer for buses to cover their routes with more poor road conditions and more passengers hopping on and off. At times, drivers need to take time and instruct passengers to move farther back and make room for additional riders. Then there are the riders in the back when a bus stops who need time to make their way through a packed aisle and out the door.

Bus passengers "have to be patient as we're all in this snow event together," Padilla said. "But our drivers pride themselves on getting people from A to B safely."