Here’s a typical Los Angeles freeway scenario: you’re driving by yourself, poking along behind an endless line of slow-moving cars, while next to you, the happy people in the carpool lane go whizzing by. One, two, three, twenty… you lose count, right? Ever think you would gladly pay a few bucks to get in there and get going?

Well, about a year and a half from now, you’ll have that very opportunity, if you’re driving on I-110 or on I-10 in LA County. The Los Angeles County Metropolitan Transportation Authority is undertaking a demonstration of what are called HOT lanes – high-occupancy vehicle lanes (i.e., carpool or “HOV” lanes) that are accessible to single drivers for a toll (hence high-occupancy/toll lanes or “HOT” lanes). Our HOT lanes are dubbed “ExpressLanes” and will be in place for a one-year pilot project in 2011, using over $200 million from a federal grant.

HOT lanes aren’t unheard of in California, the state that put the “free” in freeway. Orange County has them on State Route 91, and San Diego County has them on I-15. But these will be the first toll lanes in Los Angeles County. On I-10’s El Monte Busway, a qualifying carpool has to have three or more passengers, so during peak commuting hours both solo drivers and two-person carpools will have to pay. In off-peak hours, carpools of any size will go free. Three-person carpools will always go free, and single drivers will always pay.

Both ExpressLanes will use dynamic pricing, which means that the toll will vary according to the level of congestion. As speeds drop, tolls will edge up, providing a signal to drivers that they might want to stay out. Once you’re in, though, your toll will be as quoted when you entered; it won’t change during your trip. The lanes will also use “open-road tolling” technology, meaning there are no toll booths or buckets to throw coins into. All vehicles in the ExpressLanes will need a transponder whether they are paying or not.

What I didn’t realize before I started working on this project as part of the consulting team, is how “green” these lanes will be. There are many reasons for this. One is that a big portion of the project funding will be used to ramp up vanpooling and transit service along both corridors, particularly bus service. Transit facilities – stations, connections, security – will also be upgraded. The overall goal is to reduce congestion by enticing some people out of their cars altogether. Another reason is that new buildings built for this project will meet LEED standards for green building design.

But perhaps the most interesting reason is the ability MTA will have to influence travel speeds in the ExpressLanes. It turns out that there is an optimum speed for getting the most miles per gallon out of a car – and admit it, you know it’s not 73 mph. It’s actually about 46 mph. With the dynamic tolling, MTA will be able to influence the number of cars in the HOT lanes so that everyone stays right around this speed – predictably, all the time. In the other lanes, enough solo drivers will relocate to the HOT lanes that speeds will go up – again getting closer to the optimum speed of 46 mph. Both lanes will result in saved gas and lots of saved emissions, including those pesky greenhouse gases.

Intrigued? Upset? Puzzled? Impatient? Well, that last one, I can’t help you with, but for the others: you can get much more information on the project from its website. Note also that there will be a live web chat with the project manager on Tuesday, July 7th, from noon to 1 p.m. Tune in and ask questions!