"Those projects just can't happen in the financial reality that we face right now," said Kevin Keith, director of MoDOT. "Our focus as we move forward is to keep our assets, our roads and bridges in as good of condition as we can and keep our citizens safe."

MoDOT adopted a five-year plan to save $512 million by 2015, redirect funding to critical bridge and road projects and provide a state match for available federal funds.

Steps included reducing staff by a total of 1,200, closing 131 facilities and disposing of more than 740 pieces of equipment.

"We've been under-investing in infrastructure at the national level and the state level for a long time," he said.

Keith said the fuel tax has remained unchanged since the early 1990s, which "buys about 67 percent of what it did then. It's now a declining revenue stream."

"For 10 years, through Amendment 3, stimulus and original bonding, we have kept our construction program by borrowing, which means I'm going to build it now and pay for it in the future. But we've done all of that we can."

Passed in 2004, Amendment 3 diverted revenue from the existing motor vehicle fuel tax for work on state and local highways, roads and bridges.

"That allowed us to do $2 billion in bonding and build projects like ... the interchange," Keith said. "But those resources are now spent."

Funding for the state's highway construction program, which averaged $1.2 billion in recent years, now stands at $600 million a year.