Lenexa is planning to build a tunnel under West 87th Street Parkway to connect trails north of the busy corridor to Sar-Ko-Par Trails Park to the south.
West 87th Street Parkway will temporarily close for construction of the Little Mill Creek Trail Tunnel, but city staff and representatives of the project say they are looking for ways to expedite the process and minimize the impact to motorists.
The tunnel will be built just east of Acuff Lane and to the north of Lenexa Skate Park.
Construction is expected to take place in summer 2022 and take about 45 days to complete with a full road closure of West 87th Street Parkway.
Project representatives said that if the city opts to keep one lane open in each direction on West 87th Street Parkway, then it could double or triple construction time, increase project costs and pose a safety issue for the public traveling next to the construction site with a depth of more than 20 feet.
Total project costs are just under $2.3 million. The Kansas Department of Transportation is contributing $1.1 million to the project.
In a presentation to the Lenexa City Council on Tuesday, Cody Porter, a representative of Wilson & Company Inc., Engineers & Architects provided two design options — open trenching and tunneling.
City staff recommends an open trenching method that would cost just under $1.8 million to build. While not the cheapest option, city staff said the final look with an arch ceiling will provide a more open and appealing entrance to the tunnel.
City leaders and staff said they wanted to prioritize a good quality project that is appealing to those who would use the tunnel, as well as speedy construction to avoid lengthy road closures.
The final construction contract will include incentives — awarding $10,000 per calendar day for completing ahead of schedule, up to a maximum of $150,000. It also includes disincentives — penalizing $20,000 each day of delay — to encourage an efficient and timely project.
City staff estimates the road closure would cost about $1 million to the motoring public.
The tunnel design is expected to be 10 feet wide and a minimum of 10 feet high with accessibility accommodations. The project also involves adding lighting and emergency contact pedestals for safety, and coordinating drainage and floodplain issues and relocation of water utilities.
Below is a look at many of the design options for the tunnel path — for those who can see color, the red and green lines mark the two preferred designs.
The city expects to have final design between May and October, then work on relocating water utilities within the area. The final completion date is Oct. 1, 2022.