Device at Lafayette interchange designed to reduce traffic noise

Carpenters from Emery Sapp and Sons work in February on the shoulder of the U.S. 50 eastbound exit ramp at Clark Avenue preparing to pour the piers to support the sound wall.
Carpenters from Emery Sapp and Sons work in February on the shoulder of the U.S. 50 eastbound exit ramp at Clark Avenue preparing to pour the piers to support the sound wall.

No one likes a noisy neighbor, and highway officials hope some additions to the Lafayette Street interchange project in Jefferson City will keep the roadway in the good graces of area property owners.

Part of the interchange project includes construction of a noise wall, which is a device highway officials said will reduce highway noise levels for residences and property owners in that area.

By MoDOT standards, vegetation could be considered a sound barrier, as could fences, but walls make more of an impact.

There's no special materials in these noise walls. They are made out of concrete, some out of wood and some out of see-through Plexiglas, but concrete walls are expected to last 20 years.

Noise walls were determined to be the best way to deal with the problem in the Lafayette area, MoDOT officials said.

The noise walls met all the factors including a vote of the owners and residents of the noise-sensitive areas that would benefit from a noise wall. Seventy-five owners and residents were identified in that area, and after getting their feedback, two wall locations were approved.

The first location is along the south side of U.S. 50/63 from near the former location of the Boys and Girls Club, along Elm Street to near Clark Avenue. This wall location benefits 52 owners and residents. The second location is on the north side of U.S. 50/63, along the westbound on-ramp of the Clark Avenue interchange between the ramp and six residences on the south side of Miller Street.

There were 17 owners and residents opposed to the noise walls.

The approximate cost for the noise walls is $1.4 million.

The Lafayette Street interchange project altered the existing highway, resulting in vehicle traffic moving closer to noise sensitive areas.

The determination for noise abatement measures was actually made during the development of the Environmental Impact Statement (EIS) in 2010. Once the EIS was approved by the Federal Highway Administration, it required MoDOT to complete a noise study.

During the design of the Lafayette project, MoDOT hired George Butler Associates to complete the noise study of the project area. This involved identifying noise-sensitive areas including residences, businesses, parks, cemeteries, schools, etc.

Traffic noise measurements were taken at each location using specific sound level meters that meet federal requirements. Measurements were taken of the existing traffic noise during the peak traffic time. A computer model was used to predict the future traffic noise. A comparison was made between the existing traffic noise and the predicted future traffic noise. If the difference between the two noise levels is 15 decibels or greater, then noise abatement measures must be considered and evaluated for feasibility and reasonableness.

After the testing, noise walls were deemed as the most feasible abatement measure.

MoDOT requires at least a five-decibel reduction in noise levels for the abatement to be considered feasible, and the noise wall's height must be limited to 20 feet due to wind loads and clear space concerns.