Of the nearly 500 written comments, 77% said they consider safety "a major concern." About 71% cited truck traffic as a chief worry, according to the St. Louis Post Dispatch.
The state is considering rebuilding a 199-mile stretch of I-70 or starting from scratch on a parallel highway, possibly a toll road.
The findings were released at public meetings that began Monday. The cost of the project, depending on which option is chosen, would be between $1.7 billion and $ 2.1 billion.
Other measures such as high-speed rail, better traffic management and adding high-occupancy vehicle lanes by themselves won't provide the kind of congestion relief and safety improvements the state wants, according to officials.