Lawmakers continue to propose reduced vehicle travel as a strategy to lower fuel consumption and greenhouse gas (GHG) emissions. Unfortunately, getting people out of their cars and off the roads also means less revenue for the ailing Highway Trust Fund (HTF), which recently required a $7billion transfer from the general fund to meet its funding commitments for the current fiscal year.

There is no doubt that the transportation industry must further its commitment to the environment, but impeding our nation's mobility by enacting policies to limit growth in vehicle miles traveled (VMT) should not be a national policy. Personal freedom is a defining characteristic of the American way of life, making us the envy of others around the globe. Enacting a plan to reduce VMT is a direct attack on the freedom of American citizens, many of whom would never be able to venture beyond the confines of their job or neighborhood if subjected to VMT restrictions.

Instead of limiting vehicle use, we must become more efficient and utilize technologies to decrease fuel use and limit carbon emissions. It's pleasing to see support for a few of the sustainability recommendations already supported by the trucking industry.

Through a strong partnership with engine manufacturers, new over-the-road truck engines far exceed the environmental standards set in 2007. The Advanced Collaborative Emissions Study released by the Coordinating Research Council found that engine models produce 98percent less carbon monoxide, 10percent less nitrogen oxide, 95percent less non-methane hydrocarbons and 89percent less particulate matter than required by EPA's 2007 diesel engine emission standards. Today, if a white cloth were held over the tailpipe of a new truck, the cloth would remain spotless.

Regulatory policies to limit and enforce speed limits are also important, not only for highway safety, but also for the reduction in fuel use. ATA recommends enacting a national speed limit not to exceed 65miles per hour and govern speeds of trucks manufactured after 1992 at no more than 65miles per hour. A truck traveling at 75mph consumes 27percent more fuel than one going at 65mph. Bringing speed limits for trucks down to 65mph would save 2.8billion gallons of diesel fuel in a decade and reduce CO2 emissions by 31.5million tons - equal to a year's CO2 generated by 9million Americans. Automobile consumption of gasoline would drop by 8.7billion gallons, with an accompanying drop in CO2 emissions of 84.7million tons.

Reducing traffic congestion is also vitally important for reducing fuel consumption and carbon emissions. The Texas Transportation Institute estimates that Americans waste 2.8billion gallons of fuel each year as a result of congestion on our highways. "Lost hours" from sitting in traffic also reduce American productivity.

As we continue to focus on limiting our fuel use and reducing emissions, it is clear that we must have a system for highway infrastructure funding that will effectively support these necessary environmental goals. The federal fuel tax is still the most efficient way to collect revenue for the HTF, but it must be updated to keep up with our current needs. The current tax --18.4cents per gallon charge for gasoline and 24.4cents per gallon for diesel -- has not been adjusted for inflation since 1993, yet costs of highway projects continue to escalate with the costs of labor and materials. This is a very poor formula for maintaining a healthy, let alone robust trust fund. The simple answer for increasing trust fund revenue is to increase the federal fuel tax to increase the HTF's purchasing power. The trucking industry supports this increase, so long as the revenue goes directly to highway infrastructure and is not diverted to non-highway uses, as it has been in the past.

Whether it's a fuel tax or other alternative funding methods like tolling or VMT tax, all funding systems require that we pay for our use. Fuel taxes are the least expensive, most efficient source of highway funding available today. At present, 99cents out of every dollar in collected fuel tax goes to the HTF. Other systems such as VMTT cannot come close to offering taxpayers that efficiency. Only about two-thirds of every dollar collected in a VMTT system goes toward the cost of collecting it.

The trucking industry is deeply committed to reducing fuel consumption and GHG emissions, but these objectives do not have to come at the expense of a safe and effective highway transportation system to move the food, medicine, clothing and fuel we need to live and the consumer goods that make our lives comfortable.