I think this table speaks for itself:

SEATTLE TO PORTLAND (one-way trip, downtown to downtown) Travel time Cost Departures Alaska Air 2:42 $105 22 private car 2:56 $97 unlimited Amtrak 3:30 $32 5 Greyhound 4:25 $13 4 BoltBus 3:15 $6 4

(See the “notes and methods” section at the end of this post for details.)

Despite all the attention heaped on more glamorous modes, private intercity charter buses like BoltBus are proving to be the quiet superheroes of regional travel.

Sure, the BoltBus isn’t a perfect substitute for other modes. Unlike Greyhound or the train, the BoltBus won’t stop at intermediate destinations; and unlike a private car, it can’t take you directly to your final destination. But for the markets they serve—downtown to downtown between the US Northwest’s two biggest cities—they can compete with the best on travel time, and they crush the competition on price.

Plus, for long distance travel, intercity buses are the climate champions, generating less carbon per passenger mile than any other mode.

By boarding at the curb and traveling on the Interstate, charter buses make super-efficient use of our existing infrastructure, requiring virtually no new public spending. Now, in fairness, all forms of travel rely on hefty public subsidies and robust governance. (Highways don’t exactly maintain and police themselves, after all.) Still, the cost of adding an extra bus to the highway must be pretty close to zero—and it may even save costs, if running a bus takes a few cars off the road.

Anyhow, the arrival of BoltBus in the Northwest is good news for the region’s travelers. And it marks a very encouraging example of a private-sector solution to the conventional travel that is so environmentally damaging and increasingly costly to boot.

Notes and methods: Travel time and cost figures for Alaska Airlines, Amtrak, Greyhound, and BoltBus are calculated using each transportation provider’s website and are based on a hypothetical mid-day trip on Tuesday, May 22, 2012 for one adult full-fare passenger. Travel times assume no unscheduled delays. Alaska Airlines cost figure is based on a $99.80 ticket plus the cost of travel to and from the airports, including a $2.75 Sound Transit Link light rail fare in Seattle and a $2.40 TriMet Max light rail fare in Portland. Alaska Airlines travel time figure is based on a scheduled 50 minute flight time plus 34 minute transit time by light rail in Seattle (from Pioneer Station to SeaTac) plus 38 minute transit time by light rail in Portland (from PDX to City Center) plus 40 minutes at SeaTac to travel from the light rail station to the airport terminal, pass through security, and board the plane. (Other airlines provide service on the Seattle to Portland route; on May 2, 2012, Expedia.com listed Alaska as the lowest cost airfare with United Express close behind.) Private car cost figures are based on the 2012 IRS reimbursement rate for driving, 55.5 cents per mile, for the 174-mile driving distance calculated by Google maps. Private car travel times are calculated by Google maps and assume no delay from traffic congestion.