The Eastside Transportation Association and a team of nine high-profile Puget Sound citizens, including Islander Jim Horn, are challenging the Washington State Department of Transportation’s decision to sell or lease a portion of Interstate 90 to Sound Transit for light rail.

According to their petition, filed July 15, 2009, the group says the transfer would go contrary to the 18th amendment of the state constitution, which prohibits the sale or lease of highway lands purchased with motor-vehicle fund money for non-highway purposes.

“Sound Transit proposed to take a valuable asset, which belongs to Washington citizens, and use it for other than its intended purpose,” said Horn, a former Mercer Island mayor, former 41st Legislative District representative, former senator and former chairman of the Senate Highway and Transportation Committee.

The 18th amendment, which appeared on the November 1944 ballot and was approved by Washington state voters, identifies motor-vehicle fund money for the building and maintenance of state highways, he said, adding that public transit — including light rail — is a different thing.

“Public transit is not a highway purpose,” he said. “Those things are black and white.”

Horn believes Sound Transit’s interest in the Eastlink light rail is a non-issue.

The DOT and the governor agree that I-90 was built in part by motor-vehicle funds, and the DOT, the governor and Sound Transit agree that light rail is not a highway purpose, he said.

At the same time, the DOT argues that it has discretion to sell or lease its properties, and Sound Transit has tentatively agreed to spend $153 million for bus and carpool replacement lanes to maintain the current traffic capacity.

But the DOT and Sound Transit’s tentative agreement to fund new bus and carpool lanes is beside the point, Horn said, adding that the real cost of constructing a new highway from Seattle to Bellevue would come in closer to $10 billion.

“It would be unconstitutional to use that facility for $10 billion,” Horn said, “but it would be a slap in the face to offer one-and-a-half percent for the use of it.”

However, federal highway funds — not state funds — covered the majority of I-90’s cost.

Horn concedes that I-90 was built to accommodate light rail; however, “Saying that it could be was not saying it would be,” he said.

“We’re trying to prevent the greatest train robbery in American history,” Horn said. “The trains are robbing the people of Washington.”

The roadway belongs to the citizens of this state, he said, and their plan is to effectively steal the roadway.

“This is big enough that it has gone national,” he said of the dispute.