First stretch of Intercounty Connector toll road in Maryland to open Feb. 22

"Our goal is to give people time to try the road, get their E-ZPass and become accustomed to the ICC tolling system," she said.

A three-tiered tolling system will be used for the initial stretch opening this month. During two peak periods - 6 to 9 a.m. and 4 to 7 p.m. - it will cost $1.45 for two-axle vehicles to travel the 7.2 miles. From 11 p.m. to 5 a.m., it will cost 60 cents. At all other times, the toll will be $1.15.

Signs posted at entrances to the highway will alert drivers to the tolling period in effect.

When it's fully open, the highway is projected to carry about 43,000 vehicles a day.

Despite its grandeur in size, technology and expense, the highway is little more than half as long as the one promised in 1958. That one was to stretch in a 32-mile arc through Maryland suburbia, from just north of Potomac to Bowie.

The right of way for much of the highway that will open this year was bought before the surrounding area was developed, so construction didn't require razing many homes or other structures, as might have been the case in the densely settled suburbs.

But the project drew strong objections from environmentalists and residents who feared it would pollute the air and streams and eventually invite more congestion by encouraging development.

The Maryland State Highway Administration is carrying out a 2008 settlement negotiated with the Environmental Defense Fund over air quality.

The state is spending $1 million to install exhaust filters on 70 diesel school buses, along with $1 million to collect three years of data from an air-quality monitor near the Beltway and Route 214 in Prince George's. The results could determine how much people near highways are exposed to unhealthy particles and droplets of chemicals in vehicle emissions.

halseya@washpost.com Staff writer Katherine Shaver contributed to this report.