Truckers could run heavyweight, triple-trailer loads across the nation's midsection if a direct Chicago-Kansas City toll road is built, a new feasibility study proposes.

The ambitious plan faces serious obstacles, but would form a private utility to build a 521-mile superhighway, link up with turnpikes in Kansas and Indiana and create what it calls "a heavy truck bridge" across Illinois and Missouri.The road should draw sufficient trucking business to justify its $3 billion construction cost, according to Joe Guyton, one of the plan's authors. He is project director for the study's engineering section at Howard Needles Tammen and Bergendorff, Kansas City.

"We believe enough would want to use it, there would be enough advantages, that (trucking) would make a major contribution."

In fact, since the proposal counts on no federal money, the study says it is feasible only with substantial truck traffic paying tolls of up to 21 cents a mile for most of its length.

Financing would include bonds paid for by tolls and assessment on local economic development.

The express route would save truckers only about 80 miles compared with interstate highways through Des Moines, Iowa or St. Louis, but its main advantage would be tonnage.

The "Chicago-Kansas City Tollway" (CTC) weight limit would supersede 80,000-pound load ceilings now in Missouri and Illinois, and would permit large double or triple trailers pulled by a single tractor.

Coupled with larger limits already in place in adjacent states, that would mean truckers could run extra-large loads on turnpikes from Texas all the way to Pennsylvania, more than 1,200 miles.

And since most Western states allow the bigger loads, the CKC could help bring an eventual coast-to-coast route for longer, heavier trucks, the study suggests.

That raises concerns at the Association of American Railroads, where director of competitive policy Brian Vogel emphasized, "We are opposed to longer, heavier trucks unless they pay their full social costs."

He said the AAR must review the study and did not yet have a policy on this particular project.

The $500,000 study by private engineers and financial consultants, required by 1988 federal legislation and mostly paid for by the U.S. government as a pilot project that could affect other transportation plans, is just a first step.

The roadway would have to draw private investors since it would use no federal funds, clear legislative hurdles in both states, and overcome wariness in the trucking and railroad industries to become reality.

At the American Trucking Associations, director of highway policy John Reith was cautious.

He said truckers did not like to pay tolls on roads already built with tax dollars. However, in view of the higher load limits, "I think it's something we would consider" for potential support.

State officials said the study began with efforts from Peoria, Ill., to boost its economic development. It was helped by U.S. Rep. Robert Michel, House Republican leader, who is from Peoria.

An aide to Mr. Michel said Wednesday he had not reviewed the whole plan but, "if it can be done, he would like to see it happen."

St. Louis weighed in against a roadway that would bypass it, and there has been opposition from residents along the proposed route, a Missouri highway official said.

This state would have to change its constitution to allow such a toll road. Both states would have to pass empowering legislation and hand over parts of existing roads to the express road.

A competitor, the Central Illinois Expressway, already is being developed, although it would take another route.

"There are a lot of things working against it," the Missouri official said.

Coming from the Kansas Turnpike, the CKC would swing north of Kansas City to U.S. 36, which would of course be widened to four lanes for its entire length, then head east to Hannibal, Mo.

After crossing the Mississippi River there, it would turn northeast to Quincy and Peoria, Ill., on to Chicago and over to the Indiana Toll Road.

All existing roads that it absorbed would be strengthened for heavier trucks. Some of those areas would not be included in toll charges, and would continue to be maintained by the states rather than the toll utility.

The study also suggests the private utility could set a higher speed than now allowed on interstates, up to 80 mph for cars and 65 mph for trucks.