The state’s affiliate of the American Society of Civil Engineers pointed out recently what many Maine residents already know: The state’s infrastructure has been neglected, and a long-term and sustainable funding source is needed to make improvements. The question then becomes: What can be done to increase investment in transportation infrastructure at a time of slowing revenue from gasoline taxes?

Maine and the country have largely come to expect high-quality roads, ports and bridges but have not devoted the needed resources to keep up with expansion and maintenance. Highway spending per mile traveled has fallen nearly 50 percent since the federal Highway Trust Fund was established in the late 1950s, according to a National Surface Transportation Infrastructure Financing Commission report.

And, because the federal gas tax — 18.4 cents a gallon — is not adjusted for inflation, it has experienced a total loss in purchasing power of more than 33 percent since 1993, which is the last time the tax was increased. Couple this with people driving more fuel-efficient cars, and the funding problem becomes clear. Investment has been deferred even though, between 1980 and 2006, the total number of miles traveled by cars and trucks doubled, adding strain to existing physical structures.

In Maine, 38 percent of major roads are in “fair to unacceptable” condition, according to the civil engineers group, resulting in Maine motorists spending an average of $299 per year in extra vehicle costs. Improving roads and other infrastructure systems aids productivity. Completing maintenance on a timely schedule prevents costly replacements at later dates. State and federal officials know this.

What they haven’t agreed on is how to maintain funding levels. One proposal would have the gas tax automatically increase with the rate of inflation.

Another idea, which warrants more study, is to switch over time to a user charge system, so drivers pay tax based not on the amount of fuel they consume but on miles driven (and possibly time of day, type of road, vehicle weight or fuel economy). The purpose would be to allow targeted prices to incentivize more efficient use of roads. And, mileage devices installed in vehicles could track just distance traveled, not where they were traveled, to ensure privacy.

Maine must do its part, which includes issuing bond money approved by voters. Using bond money to pay for transportation projects isn’t an ideal option because it’s not a regular funding stream. But that’s not a reason to delay issuing bonds, as Gov. Paul LePage has done, especially when there are few other options to pay for transformational infrastructure improvements.

The necessary factors have aligned to make issuing voter-approved bonds the right choice: Voters recognize the need; improvements have the ability to spur development and put contractors to work; interest rates are low; and the state has the borrowing capacity.

The state can also do its part to employ creative financing methods. One way to accelerate construction, for example, is to use Grant Anticipation Revenue Vehicles, where the state is advanced upfront funding in anticipation of future, expected federal funds. The state can also complete projects faster and more efficiently by having project designers and builders work together when appropriate — instead of the traditional routine where designers lay out the project, and it’s subsequently put out to bid.

Maine has had some recent transportation successes — including the expansion of Amtrak passenger rail service to Brunswick — but more must be done. Innovative answers will come from both the federal and state government, as they both contribute to the building and maintenance of infrastructure. Solutions should focus on ease of travel, making operations more efficient and filling funding gaps in a sustainable and fair way.