The New York State Thruway Authority’s proposal to increase truck tolls by 45 percent is getting a lot of pushback from lobbyists and politicians in Albany, including Comptroller Thomas DiNapoli and Assembly Speaker Sheldon Silver. But not only do the Thruway’s truck tolls fall in the middle of the road when compared to tolls in other states, trucking companies in New York are paying a disproportionately low cost for the damage their vehicles cause to roadways.

The level of Thruway tolls matters to all New Yorkers because transit funding has a history of being diverted to plug holes elsewhere in the state budget. If the owners and operators of the heaviest, most damaging vehicles on the Thruway don’t pay their share for system maintenance, straphangers could be left indirectly footing the bill.

Today, the operator of a typical 18-wheeler pays $6.78 for every dollar a car driver pays on the Thruway in Orange, Rockland and Westchester counties. Across the entire Thruway system, trucks get an even better deal, paying “only five times the rate of the average passenger vehicle,” according to Thruway Executive Director Thomas Madison Jr.

Under the toll increase, which would not apply to cars, trucks would pay $9.89 for every dollar in auto tolls. That might seem steep to most drivers, but consider the costs that go unpaid.

Although adding more axles to large trucks blunts their impact on the road, the average 18-wheeler weighs twenty times more than a two-ton automobile.

This is important because the damage inflicted on the road surface doesn’t increase linearly along with vehicle weight. In fact, wear-and-tear increases exponentially as vehicle weight increases. According to a report by Jacobs Civil Consultants for the Thruway Authority [PDF], an 80,000-pound, 18-wheel truck creates the same amount of damage as 9,600 passenger vehicles.

No one in New York is even thinking about an exponential increase in truck tolls, but the outsized impact of heavy trucks on road maintenance shouldn’t be forgotten as the toll hike, which only needs the consent of the Thruway Authority board to proceed, draws closer. If approved at this month’s board meeting, it could go into effect as soon as September 30.

One argument against the toll increase is that it would place New York at a competitive disadvantage. But the Thruway’s truck tolls — even after the increase — are comparable to rates in adjacent states.

Presently, the Thruway’s peak toll rate per mile of highway for five-axle trucks is lower than rates for the New Jersey and Pennsylvania turnpikes. After the toll increase, it will be slightly higher than New Jersey and Pennsylvania, with per-mile toll rates on par with I-95 in New Hampshire.

In some ways, this debate completely misses the big picture: The chief competition for freight across and within New York isn’t other state turnpikes, but railroads, and making the playing field more favorable for freight rail will have major environmental and quality-of-life benefits.

The Thruway Authority must raise revenue to avoid a credit downgrade. Madison and Governor Cuomo have called on the highway’s heaviest users to pay, if not their fair share, at least something closer to it. They deserve credit for holding firm so far. They will need the same type of commitment — and then some — to ensure that users of the new Tappan Zee Bridge, not NYC straphangers, pay for that project.