Pennsylvania has good reason to protect its highway system. With the nation’s fifth-largest network of state-maintained roads and the fourth-highest number of interstate miles, Pennsylvanians rely on transportation as the backbone of our state’s economy. And investing in this vast system is essential to safely moving goods and people through it.

After decades of underinvestment, the highway network stands to benefit from Gov. Tom Corbett’s plan to inject nearly $2 billion into its maintenance.

Corbett’s transportation bill, the first in six years, is badly needed since the gas taxes and motorist fees that largely fund highways and bridges have not increased since the 1990s, and aren’t going as far anymore because of fuel efficient cars that use less gas to drive the same number of miles. In addition, inflation has made construction more expensive.

The highways proposal is a key element in Corbett’s 2013-14 budget, which faces a Sunday deadline for adoption. It’s one of several components still taking shape as that deadline approaches. Other key parts include education, pension reform and impact fees on natural gas wells.

The plan follows recommendations by the Transportation Funding Advisory Commission, a panel Corbett created in 2011 to study the issue. The commission determined Pennsylvania’s transportation needs outstripped available funding by more than $3.5 billion a year.

The state Senate introduced a more aggressive approach, adding another half-billion dollars to Corbett’s plan, to be raised within five years. On Monday, the House introduced an amended version that scales back spending to nearly what the governor originally proposed. A vote on the House-amended version was delayed later Monday to allow caucus members more time to discuss it.

The Senate version would raise money for public transit by adding a surcharge on moving vehicle violations. The House amendments eliminate the surcharge and would also require local governments to pay a higher share of the costs of transit. Counties would be allowed to levy a $5-per-vehicle fee on residents and raise sales taxes, realty-transfer taxes and earned-income taxes.

All three transportation funding plans would make the full wholesale price of gasoline subject to a tax paid by distributors, rather than just a portion, a practice originally intended to stave off inflation.

The House version of Corbett’s initiative strikes a realistic balance for the state’s current fiscal circumstance. It provides for highway maintenance, which is crucial to Pennsylvania’s economy, without placing unnecessary financial burdens on what continues to be a fragile economic recovery. It merits support.