The Olathe City Council voted 7‑0 on Nov. 3 to approve an additional $567,375 for engineering services from Kansas City‑based firm HNTB. The contract covers design work for bridges, retaining walls, drainage and traffic‑flow planning as the city moves forward with the I‑35 and Santa Fe interchange project.
Project timeline and scope
Construction on the highway portion of the I‑35 and Santa Fe interchange could start as early as this winter, according to city documents. The Kansas Department of Transportation (KDOT) will add auxiliary lanes between Santa Fe and 119th Street in late 2026 or early 2027, with the broader Santa Fe corridor rebuild scheduled for late 2027.
Utility crews are already relocating lines in the area, and the city estimates the roughly $200 million project will be completed by summer 2030. The $40 million share that Olathe is contributing will be funded through general‑obligation bonds, while KDOT and federal grants will cover the remaining costs.
Engineering details
City Engineer Nate Baldwin told council members that the HNTB agreement is part of the overall budget and that additional work may be added as project details become clearer. “In the beginning, you couldn’t really imagine what the retaining walls and the bridges are going to look like, what the Federal Highway Administration’s going to ask for, what additional information KDOT needs,” Baldwin said. “So that’s what we’re looking at here. This is just a next step.” He added that the new agreement will not affect the construction schedule.
The project will replace the existing I‑35 interchange with a single‑point urban interchange (SPUI), similar to the one at 87th and I‑35 on the Lenexa/Overland Park border. A SPUI allows left‑turning traffic to move through a single central signal, providing more space for large vehicles and smoother flow through the intersection.
Impact on drivers
KDOT also plans to rebuild pavement along I‑35 and widen the Old Highway 56 bridge to accommodate the two new auxiliary lanes. Drivers should expect some road closures, though the intersection of Mahaffie Street and Old Highway 56 will remain open.
The most significant traffic impacts are expected during the final phase of the city’s portion of the project in 2029, when the interchange will be rebuilt, Santa Fe Street will be reconstructed, and Rogers Road will be extended. During that phase, Santa Fe will close completely.
Community benefits
The entire effort is intended to address congestion and safety along one of Olathe’s busiest corridors. By adding auxiliary lanes and modernizing the interchange, the city aims to improve travel times for commuters, support local businesses that rely on efficient freight movement, and enhance overall roadway safety for families and residents.
City officials emphasized that the project reflects a partnership between Olathe and KDOT, with the state agency managing the I‑35 portion and the city overseeing work along Santa Fe. The collaborative approach is designed to keep the project on schedule and within budget while minimizing disruption to daily traffic.
Looking ahead
As construction progresses, Olathe will continue to provide updates on road closures, detour routes and any changes to traffic patterns. Residents are encouraged to stay informed through the city’s website and local news outlets.
Original reporting: Johnson County Post (Overland Park) — read the source article.
