(KANSAS CITY, Mo., AP) — A gap exists between the transportation system that Missourians demand and the one the state can provide with current funds, a report released Thursday said.

Missouri Department of Transportation officials outlined more than $70 billion of wants, needs and projects from across the state in unveiling a draft of its latest 20-year plan during a meeting at Kansas City’s Union Station.

But MoDot, which talked to residents statewide in developing the report, said that amount is significantly greater than the estimated $17.3 billion of funding available over the next 20 years. One of the most expensive proposals, improving Interstate 70 between Kansas City and St. Louis, would cost from $2 billion to $4 billion. The lower estimate would expand the more than 200-mile route to three lanes; the higher would add a dedicated trucking lane.

“The biggest challenge we face in keeping Missourians safe is a tremendous gap between what Missourians need and want and what we can continue to fund,” wrote transportation director Dave Nichols. “Without a funding solution, we will be hard pressed to even maintain the existing system.”

Nichols said that between 2005 and 2009, funds made available by a voter-approved constitutional amendment allowed the state to make significant improvements. The amendment directed motor vehicle sales tax revenues and other highway user fees to the Department of Transportation, instead of the state’s general revenues, and authorized road bonds to be paid off with that influx of money.

MoDOT has been warning for years that its annual highway construction budget would decline significantly as bond payments for those projects came due. That drop-off has now hit: The annual construction budget has fallen from $1.2 billion to less than $700 million, and it’s projected to drop to $425 million by 2019.

Missouri’s highway system has long depended on fuel taxes. But the report, which is required by federal law, said people drive less and vehicles are more fuel efficient. Meanwhile, inflation is increasing the cost of projects, the report noted. The price of asphalt, concrete and steel are double and triple what they were 20 years ago, when fuel taxes were last raised, the report said.

MoDot said that without more money, it will have to make cuts to basic services, such as highway resurfacing, or make few improvements to the existing system.

“When given these options, participants said something needs to be done about the decline of transportation funding in Missouri,” the report said, referring to meetings it held statewide as it developed the report.

Lawmakers earlier this year considered but did not pass a proposed 1-cent sales tax for transportation projects that would have been referred to the statewide ballot.

But the issue may resurface. Last month, a group submitted a proposed initiative petition to the secretary of state’s office that would ask voters in November 2014 to approve a 1-cent sales tax for transportation. Ten percent of the revenues would be split between cities and counties, with the remaining 90 percent going to MoDOT for roads, bridges, airports, railroads, river ports and other modes of travel. The Missouri Highways and Transportation Commission would be responsible for coming up with a list of projects to be funded by the new tax.

Supporters of the proposal already have begun raising money, but they must wait for approval from the secretary of state’s office before they can begin gathering the petition signatures needed to get it on the ballot.

“We want a better tomorrow for transportation, but how do we pay for it?” asked Highways and Transportation Commission Chairman Joe Carmichael during a news conference. “And that is a huge question.”