Owners of the Dulles Greenway, the 14-mile road connecting Loudoun County to Dulles International Airport and the Dulles Toll Road, are again raising tolls, effective Jan. 1. And this time, they're also eliminating the discount for Smart Tag users and for travel during non-peak hours.

The combined effect of these changes will have those who drive the length of the Greenway paying as much as 42 percent more per trip.

On weekdays, drivers in two-axle vehicles will pay $3.20, with 50 cents of that paying either for entrance to or exit from the Dulles Toll Road. The toll on larger vehicles will increase to $6.40, with a dollar going to the Dulles Toll Road.

On weekends, the toll will be $3 for two-axle vehicles and $6 for larger vehicles.

Asked about the toll increase, Anne Huggins-Lawler, marketing and public relations manager of the toll road's operator, Toll Road Investors Partnership II, replied, "We feel that we offer good value for the money to motorists in the form of time, savings and less stressful driving conditions than surrounding road networks."

The rate increase, the sixth in 10 years, comes about three months after the controlling interest in TRIP II was sold to Macquarie Infrastructure Group, an Australian company, for $533 million. Company officials said at the time that tolls would change only according to existing plans.

Those plans were approved in July 2004 by the State Corporation Commission and set a 30-cent toll increase, to $2.70, for two-axle vehicles and a 60-cent increase, to $5.40, for vehicles with three or more axles.

But neither Macquarie nor TRIP II made any assurance regarding the discounts.

And so, beginning Jan. 1, the 40-cent discount for off-peak travel -- first implemented in September 2004, when tolls were last increased -- and the 10-cent discount for Smart Tag usage will disappear.

"The traffic pattern was not changing significantly" with the off-peak discount, Huggins-Lawler said. The pricing was designed to encourage usage beyond morning and evening rush hours.

About 70,000 vehicles travel the Greenway daily, and Huggins-Lawler said it was unclear to TRIP II whether the new price would discourage drivers from using it. The road offers an east-west alternative to Routes 7 and 28, with no stoplights and a speed limit of 65 mph.

Nevertheless, it has faced major challenges since its construction in 1993. The Greenway has lost money every year since opening in 1995, and its debt load has been a recurring worry.

More recently, the Greenway's challenges primarily have involved keeping up with the growing number of motorists. In March, six capital improvement projects were begun -- the most since the road's inception -- with the aim of reducing congestion. The work includes widening the road from four lanes to six and expanding the main toll plaza from 10 lanes to 18.

A sign in the median on the Dulles Greenway warns drivers of the upcoming adjustment of toll charges, the sixth increase in 10 years.