159th Street Reconstruction (Nall Ave. to Mission Rd.), Overland Park, KS
Contractor: Miles Excavating, Inc.
Owner: City of Overland Park
Engineer: Affinis Corp.
This project is in one of the fastest-growing area in the county. Increased traffic volumes had elevated the need for this project, which expanded the 159th Street from a two-lane country toad to a four-lane, divided roadway.
The approximately $8.93 million project also included other improvements, including bike lanes; a new roundabout at the Mission Road intersection; curb and gutter; and storm sewers. The project also called for a reinforced concrete box culvert under the road; street lighting; sidewalks; and a multi-use trail.
Some of the challenges on this project were anticipated, including the need for significant grade changes that required large solid rock excavation; utility relocations before and during construction; and continuous access to a utility substation and three nearby schools.
One factor that was less predictable was the number and frequency of 100-year rain events during the project. The project team worked together to rise to the challenge and overcome each one without sacrificing safety or schedule along the way.
Miles Excavating placed the roadway on a base comprised of 8-in. fly ash compacted subgrade and 6-in. AB-3 modified aggregate.
Large areas of rock required over-excavating the rock to a 9-inch depth below the normal subgrade, then replacing it with a drainable base layer. The modified AB-3 remained above as the base. A layer of shale was discovered at the Mission Road intersection, so after consulting with a geotechnical engineer, the fly ash treated subgrade was replaced with an additional 6 inches of modified AB-3 for a total thickness of 12 inches.
During construction, the city and contractor focused attention on sustainability measures. For example, concrete was chosen for the roadway because of its inherent sustainability benefits, including reduced maintenance and reduction of waste, such as millings associated with asphalt overlays. The contractor and city also hired a water pollution control manager to oversee erosion control on the project. Because of the steep slopes and large areas affected by the project, this was instrumental in combatting the large rain events. Some of the measures used included hydraulic erosion control; erosion control mats; biodegradable logs; and temporary seeding. The project also included post-construction stormwater treatment devices and four hydrodynamic separators installed at low points on the project. These units will collect sediment and trash from the roadway in the future.
The contractor place 35,377 SY of concrete for a total of just over 5 lane miles of roadway. The contractor used both slip form paving (for the mainline portion) and fixed form paving, mainly at the roundabout and its approach legs, as well as at main intersections.
As a result of the exceptional team effort, this rapidly-growing area now has a arterial roadway that will serve the city for many years.