Entering downtown New Braunfels from Interstate 35 on Seguin Avenue has been a bottleneck for years.
"It's too small for today's traffic volume,” Michael Meek with the Greater New Braunfels Chamber of Commerce said.
Meek says the two-lane underpass doesn't just cause traffic problems, it's also dangerous.
"We see it as a big safety issue in our community and there's been a lot of accidents there and in those times when we have high water events or heavy rainfall that area floods," he said.
After nearly 20 years of planning, the road will be closed Monday to allow workers to add two additional lanes.
Nathan Rodriguez works at Razor Tite, a barber shop on the west side of the underpass.
"I'm hoping they just knock it out as fast as they can so that the road will open back up and traffic flow will be a lot easier," he said. "With them closing it, it will definitely affect a lot of the smaller businesses here in town."
Crews with the Texas Department of Transportation will have to build a detour route for the train. Once the detour's in place, the train crossing will be rebuilt and the road expanded.
The project is expected to be finished in the spring.
"We'll do the best we can and get people used to it,” Meek said. “There's a lot of ways to get to where you want to go in New Braunfels."
The historic stones that currently line the street will be saved and used in the project. Detour signs will go up early Monday morning.
The project is expected to cost about $11 million.