There are growing signs that higher energy prices are prompting changes in people's transportation habits, albeit ever so slightly, throughout Pennsylvania.

Ridership has increased at the Port Authority. Statewide, gas and diesel tax receipts have dropped, a reflection of lower fuel sales. And Pennsylvania Turnpike traffic, while up a shade, has risen less than toll road officials had forecast.

An anomaly: Downtown parking garages and lots are still posting "full" signs on weekdays despite some of the nation's highest rates.

Total bus, trolley, paratransit and incline ridership at the Port Authority went up 2.8 percent in February, to 5.2 million rides, compared to February 2007 (the statistics included an extra day because of Leap Year). On a daily basis, the biggest gain was on the T -- up 4.3 percent weekdays and 14.6 percent Saturdays.

Chief Executive Officer Steve Bland has been encouraged most by a dramatic increase in productivity, an industry measure of passengers per hour of service. A Pennsylvania Transportation Funding and Reform Commission criticized the authority in 2006 for having one of the worst productivity records among peer transit agencies.

"In my mind, that's our ridership news," Mr. Bland said of the gains.

Despite record service cuts last June and across-the-board fare hikes in January, overall productivity increased 15.2 percent in February compared to a year earlier, meaning, for example, that light-rail vehicles that averaged 57 riders per hour a year ago carried 68 riders this February. Buses gained four riders, to an average 31.7 riders per hour.

"This represents efficiency ... maximizing the return on the public's investment in transit," Mr. Bland said. "It addresses one of the main criticisms leveled against us."

The Beaver Valley Transit Authority's ridership has been on a steady rise for years, including about 10 percent this year on buses that carry commuters to Pittsburgh.

Nonetheless, the Downtown parking demand remains strong, according to Dave Onorato, director of the Pittsburgh Parking Authority, which operates nine garages and the 700-space Mon Wharf.

"We're still filling up and having a good year, although you'd think that wouldn't be the case because of the high gasoline prices," Mr. Onorato said. "We're at 97 percent capacity every day on average and 105 percent at the Oliver Garage [under the new Piatt Place]," where attendants park cars in aisles by mid-morning.

Statewide, gasoline sales that amounted to 5.2 billion gallons in the 2004-05 fiscal year dropped to 5 billion gallons by 2006-07, while diesel fuel sales have remained consistent at 1.4 billion gallons a year.

Because the statistical reports lag actual fuel sales by at least four months, they don't necessarily reflect the impacts of recent record-setting gas and diesel prices.

But for the second month in a row, up-to-date tax collections reported by the state Department of Revenue showed that receipts are down in the Motor License Fund, where liquid fuels taxes bring in the most money.

Collections totaled $193.4 million in March, $6.8 million below estimates. Collections for the fiscal year now total $1.9 billion, which is $31.4 million, or 1.6, percent below estimates.

Class 1 automobile/light truck traffic for the first two months of the year on the Pennsylvania Turnpike system averaged 402,067 a day, almost the same as last year. Daily average traffic was adjusted to account for the extra day in February this year and for two days in February 2007, when the toll road was opened for free travel after a snow emergency closed interstates and stranded thousands of people for more than 24 hours.

The Pennsylvania Turnpike statistics are consistent with those of 15 other toll road agencies surveyed by TollroadsNews, an independent publication that covers toll agencies.

"Normal annual growth is in the 1 to 1.5 percent range," its editor, Peter Samuel, wrote, "so toll traffic is showing signs of weakness from high fuel prices and the beginnings of an economic recession. But the overall numbers aren't at all dramatic."

Some motorists have already started changing their ways, including buying vehicles with better gas mileage, but how much higher will energy prices have to go before people wise up?

Are you prepared to pay $3.60 a gallon by Memorial Day?

Will gasoline have to go to $5 before you consider public transit, ride-sharing and trip consolidation?

Does "Junior" still drive to school while half-empty buses pass the house?

Do you go 75 mph in a 55 mph zone, "gun it" up hills and make jack-rabbit starts that contribute to our gluttonous fuel consumption?

Are you feeling a bit guilty?