Last week the state Senate passed a long-overdue transportation bill, just a month after the University of Michigan released an analysis finding that vehicle fuel efficiency in the United States has reached an all-time high, an average of 24.6 miles per gallon. That is an extraordinary reversal from just 20 years ago, when fuel efficiency was declining in a sea of gas-guzzling sport utility vehicles.

Those matters are directly related because motor fuel taxes pay for most of the maintenance and repairs for highways and bridges. Higher vehicle mileage is great for the environment but not for the state treasury. More vehicles use an aging transportation infrastructure while using less fuel and generating less revenue per vehicle.

The state government has been slow to adjust and the roads and highways show it. The Senate bill finally deals with the reality of the modern transportation system. It would increase state spending on roads, bridges and transit by $2.5 billion a year, nearly 50 percent of the $5.3 billion that will be spent this year on those projects.

According to PennDOT, the extra money could double the number of bridges to be repaired over the next 10 years and reduce a backlog from 4,400 bridges to 1,000.

Motorists would pay for the improvements through an increased tax on gasoline at the pump, which would result from lifting a cap on the oil franchise tax on the wholesale price of fuel. License and registration fees would increase and speeders would pay a $100 infrastructure surcharge with their fines.

In addition to safer roads that better serve the economy, a major upside to the bill would be the economic impact. It would create thousands of construction jobs and more throughout the construction supply chain, boosting the economy and return some money to the state treasury through increased income and sales taxes.

The downside is the cost to motorists. But the long-term costs of doing nothing - dangerous roads, weight restrictions on bridges, snarled traffic - would be even greater.

Gov. Tom Corbett and the House have favored a less aggressive plan, priced at about $1.8 billion a year but funded through the same mechanisms targeted by the Senate.

The bipartisan 45-5 vote in the Senate indicates the seriousness of the situation despite the political risks inherent in raising taxes and fees. Now the House and the governor must summon similar political courage to move the state forward despite the political risk.