Like most of you, I am relieved that the Second Street improvement project is completed and has been placed back into service. Second Street is a main thoroughfare through Beatrice, connecting to the Industrial Park area and functions as a by-pass of the downtown traffic. This stretch of roadway on average sees approximately 3,250 vehicles per day, with a portion of those being larger commercial trucks or farm equipment. This amount of traffic and heavy loads were a key factor in the design to make sure that the replacement of Second Street would last.
I’m sure most of you are familiar with the expression, “A structure is only as good as its foundation.” This is a true statement even when it is referring to roadway designs. The existing Second Street, from Court to Ella (the section in front of the Gage County Historical Museum) had a brick surfacing that was made up of three components.
First, you had the existing subsoil, which was covered by a 1- or 2-inch thick sand leveling course which supported the bricks. This type of roadway system is very susceptible to water. Rainwater on the surface leaches between the bricks down through the sand layer, where it then encounters the subsoil. Once the subsoil is saturated, it no longer functions as a hard stable base and begins to deform or move. Hence, causing all of the sink holes and bumps that some of us became very familiar with that caused our cars bottom out if we were traveling a little too fast.
In an effort the keep this from happening again, the new brick roadway you see today is comprised of six components. First, 8-inches of the existing subsoil was chemically stabilized with monohydrated lime. This lime arrives on site as a powder in a large tanker truck. It is distributed evenly over the entire roadway sub-base at predetermined rate and mixed into the top 8-inches. This layer conditions the soil, making it a very hard base that will keep its shape and strength, even if water is encountered.
Next, a 4-inch rock foundation base course was laid. This base course allows water to travel under the above roadway over to trench drains that were installed the length of the project. These trench drains outlet the water into the existing storm water system. A 6-inch concrete pavement section was poured over the aggregate base. This pavement section gives support and a uniform surface for the brick. Weep holes were drilled through the concrete pavement and even intervals to allow water from the surface to access the drainage course below for removal.
A geotextile fabric was laid over the concrete, followed by a 1-inch sand layer. The geotextile fabric acts as a filter, allowing the water to wick through but keeping the sand in its correct location. The last component, and the only one most of you see is the bricks.
Our hope is that these measures taken in reconstructing this brick roadway will not only look aesthetically pleasing, but will also last and perform for many years to come.