Columbia, Mo. ? The city must double its spending on roads to keep up with the demand from drivers, city-hired consultants have concluded in their effort to come up with a funding plan to fix and build city streets through 2030.

“It’s a big gap, but we’ve seen much worse than that” in other communities, said Mike Wahlstedt of Kansas City-based TranSystems Corp., one of three firms advising the city’s Transportation Finance Advisory Committee.

The study said the city spent about $10 million a year on building and maintaining roads but should be spending about $20 million.

Drawing the attention of committee members was a map in the study that showed a wide dispersion of buildings — mostly businesses — that generate 20 or more trips per day.

Member Karl Kruse said that if the city could develop policies to encourage more “linear” growth concentrated in smaller areas, it probably would save money in road costs.

“That’s why there should be incentives for more dense development,” Kruse said.

“It’s really tough to implement,” City Manager Ray Beck said. Among the possibilities is reducing development fees or surcharges on developers who build in already-developed parts of the city, where new roads and utilities would not have to be built.

Kruse said more compact development was accepted in many cities but said it had to be well-designed. “We have no design standards,” he said.

The study projected metropolitan population going from 107,103 to 174,893 by 2030.