For the past three years, Kansas Turnpike Authority engineering crews worked diligently with contractors to keep the I-70 widening project on schedule, while minimizing customer inconvenience. To do this, KTA used rolling road blocks instead of road closures to add a third travel lane in both directions of the 12.6-mile project between the East Topeka Toll Plaza 183 and the Lecompton Toll Plaza 197.
The added travel lanes were needed to alleviate commuter congestion in that corridor of I-70, which is experiencing rapid growth in customer traffic counts.
To accommodate the widening project, 1,140,134 cubic yards of excavation was required to expand the turnpike from two to three lanes. The existing two-lane interstate was built with a barrier wall median, a 10-foot inside shoulder, two 12-foot travel lanes and a 10-foot outside shoulder. The original roadway was constructed with a 1.5 percent cross slope that drained from the median to the outside shoulder. The existing roadway was built with a 10-inch aggregate base, capped with a four-inch asphalt base, followed by a four-inch asphalt drainage course providing drainage to the outside shoulder; and the drainage course was then topped with 10-inches of asphalt pavement placed in several layers as binder and surface courses.
This particular section of roadway was reconstructed in 2000, when the original concrete roadway was pulverized and a new HMA surface was placed. During the current expansion only the top surface course and a portion of the underlying binder course had to be milled off in order to accommodate a new slope and to match the surface of the additional travel lane.
Since the project involved adding another travel lane in each direction, changes were required to achieve proper drainage over the expansive paved surface. The slope of the inside travel lane and the inside shoulder was inverted to allow water to drain toward the median.
To minimize traffic disruptions during the project, excavation and paving of the additional lane was completed first in order to then move traffic to the new lane while the inside lane and shoulder were milled to change the drainage slope. This process allowed the existing two lanes to remain open to traffic while the expanded third lane was constructed. With the third lane constructed, the scheduling process was able to maintain two open lanes to traffic while the inside lane was shut down to correct the drainage slope.
This particular section of roadway carries a lot of commuter traffic, and to accommodate the heavier traffic counts during the morning and evening commute, there were time limits placed on lane closures. Hamm worked nights and weekends, during low traffic volume, to also minimize traffic disruptions. The KTA engineering crews also designed and built four sets of mainline bride and asphalt widening tapers to help maintain uninterrupted traffic flow throughout much of the project.
When the new outside lanes were completed, traffic was shifted to the two outside lanes. This allowed the contractor to remove the existing median, place 100 median drain boxes, construct a new 51-inch-high barrier wall, mill the new inverted cross slope, and place new pavement to maintain the required depth of a standard KTA pavement section. With the inside lane completed, traffic was then moved back to the inside lane to allow for final overlays to be placed on the center and outside lanes, and shoulder.
All existing cross road drainage on the project was replaced with new cross road pipes, along with all new median drainage pipes. The pipes were replaced by jacking pipe under the existing roadway so as not to disrupt traffic.