Looking west on Lee Highway, lines of cars split between taking I-66 vs. staying on Lee Highway during rush hour Monday. (Jahi Chikwendiu/The Washington Post)

Tolls were lower on the Interstate 66 express lanes Wednesday morning, and traffic counts have increased slightly on several arterial routes since tolling began Monday.

So does that mean commuters are fleeing the high tolls and exacerbating congestion on other major Northern Virginia routes? Maybe. Maybe not.

The Virginia Department of Transportation said traffic was up slightly on routes 7, 29, 50, 123 and 193 during the morning and evening commutes Monday and Tuesday.

The data could hint at a slight shift in traffic patterns along the I-66 corridor, as commuters seek alternative routes to their destinations to avoid tolls. However, the spillover traffic so far hasn’t equated to significant delays on the side roads, officials and experts said.

Metro hasn’t seen a dramatic boost in ridership increase in stations along the corridor either. According to the transit agency, the four stations at the western end of the Orange Line saw a slight increase in ridership Tuesday, after a slight drop Monday. But the Vienna Metro station, just outside the tolling portion of I-66, saw a boost in entries both days. This is the stop commuters coming from outside the Beltway would most likely use to get to downtown.

The overall change in ridership of 3 percent to 4 percent at those stations is within the range of normal variation, Metro spokesman Dan Stessel said.

During the Wednesday morning rush hour, solo drivers on I-66 express lanes faced tolls near $23 for the 10-mile stretch from the Capital Beltway to the District line. That was much lower than Monday and Tuesday, when tolls hit $34.50 and $40, respectively.

State transportation officials say demand to use the lanes is lessening, leading to the lower toll rates. (In a dynamic toll system, rates continually adjust to traffic conditions — prices go up when the lanes get full and decrease when traffic is lighter).

On Monday, the alternative routes to I-66 saw traffic counts rise between 6 and 8 percent in the morning commute. Route 29 saw the biggest impact, with a traffic increase of 8 percent in the morning and up to 11 percent during the evening rush.

Still, preliminary data suggests that travel times haven’t worsened. Since Monday, commute times have been shorter in the corridor, according to INRIX, a leading traffic data firm. At 9 a.m. in the days and weeks before the toll change, it took drivers just over 20 minutes to commute between the Capital Beltway and U.S. Route 29 in Rosslyn, the firm said.

Monday and Tuesday, analysts found, the same trip took 10 to 12 minutes. The westbound afternoon commute Monday was cut in half to 10 minutes at 3 p.m.

This doesn’t mean the spillover traffic won’t have an impact. December travel times can be tricky to predict since many people travel for the holidays and commuting patterns change, analysts say.

The perception on the roads, by commuters and residents in Arlington, has been that surface streets are even more backed up than before the toll lanes opened.

“Those cars didn’t disappear, they are traveling from D.C., to Fairfax, via residential streets endangering life,” an Arlington County resident said in an email.

Arlington County officials say the county is using traffic cameras to monitor a few routes and intersections during peak hours. But they say it’s too early to make any judgments.

“Since it’s only day 3, we’re not yet able to draw any conclusions about the impacts of tolling,” county spokesman Eric Balliet said.