The rst noise wall in Ohio was built in 1975 on I-270 near Gahanna in the metropolitan Columbus area. Since then, more than 137 lineal miles of noise walls have been built as part of the state and federal highway system. This total is among the top ve states in the U.S., and it makes sense: despite Ohio’s agricultural roots, it proportionally has more lane miles of freeway and more urbanized area (noise sensitive area) than any state in the union.
Even though new highway and freeway construction has slowed in our state since its peak roughly 30 years ago, you may have noticed that many new noise barriers are still being erected. This usually occurs where an older section of freeway or highway is being widened or otherwise signicantly improved in terms of trafc capacity. In the last several years, ODOT has installed an average of about 13 miles of new noise wall each year, at a cost of about $1.5 million per mile. In the last decade in particular, aesthetic treatments for noise walls have become more integrated in wall material selection and design.
Federal Rules (and Measures) Apply
Noise impact mitigation (whether employing walls or other strategies) must meet FHWA rules and regulations and ODOT abatement policy, including the measure of cost-eectiveness. In most situations, the proven and preferred method involves a noise wall.
Pros and Cons of Wall-Type Approach
Noise walls oer proven acoustic function, a standardized design template, conventional construction methods and, perhaps most importantly, a narrow footprint that usually has minimal additional right-of-way needs or conicts with drainage and other highway wayside elements. Noise walls also usually eliminate the need for separate right-of-way fencing. Disadvantages include cost, structural and subsurface foundation requirements, repair and eventual replacement needs, visual and aesthetic limitations and, in some situations, the potential for reected noise. Visual and aesthetic issues often are referenced when it comes to noise walls, from both the motorists’ perspective as well as that of the protected adjacent land use.
Scenic Ohio is starting to examine possible options to conventional noise walls that might provide a ‘greener’, more aesthetically pleasing outcome for certain situations in our state, and still meet state and federal objectives.
The use of vegetated beltways and berms for noise and aesthetic abatement of highway corridor impacts is a common practice in Europe, but vegetation alone is of very limited effectiveness in reducing traffic noise. In recent years, fairly inexpensive earthen retaining wall systems have made more compact, plant-able earth berms a practical option where footprint conditions permit, as shown in the image below.
Taken further, these berms can be congured and planted to provide a more natural noise barrier along highways, as well as provide other benets in the areas of storm runo reduction, thermal buering, and particulate and emissions management.
Scenic Ohio will be working with ODOT in 2009 to explore how some of these options might be able to reduce costs, provide a more pleasing aesthetic outcome, and perhaps deliver more than just noise control benets for Ohio’s citizens and motorists.
Rick Record is principal of RL RECORD LLC, Cincinnati-based consultants in transportation and the environment, and a Scenic Ohio board member.