Construction on the highway portion of the I-35 and Santa Fe interchange project in Olathe could begin as soon as this winter.

According to city documents, the Kansas Department of Transportation is set to start adding auxiliary lanes between Santa Fe and 119th Street in late 2026 or early 2027.

The Santa Fe corridor rebuild is scheduled to begin in late 2027. In the meantime, crews are already relocating utilities in the area. The city estimates the roughly $200 million project will wrap up in summer 2030.

City approves more design work

The Olathe City Council voted 7-0 on Nov. 3 to approve $567,375 in additional engineering work by Kansas City-based firm HNTB. The agreement covers design work for bridges, retaining walls and draining, as well as planning how traffic can continue to flow during construction.

City Engineer Nate Baldwin emphasized to the city council that this work was already a part of the total budget and that staff anticipated adding to their contract with HNTB as project details became 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.”

Baldwin said the additional agreement won’t impact the construction timeline.

About the project

The entire project is intended to address congestion and safety along one of Olathe’s busiest corridors.

The city and the Kansas Department of Transportation are working together to construct a complete overhaul of the corridor, with KDOT managing the I-35 portion and Olathe overseeing the work along Santa Fe.

The existing I-35 interchange will be replaced by a single-point urban interchange (SPUI) similar to the one at 87th and I-35 on the border of Lenexa and Overland Park to the north.

According to Olathe, this type of interchange allows left-turning traffic to move simultaneously through one central signal, giving more space for large vehicles and smoother movement through the intersection.

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 during that time, including:

• Southbound Old 56 off-ramp for three months
• Old Highway 56 bridge while it’s widened and reconstructed for six months
• Northbound off-ramp at 119th Street for three months
• Southbound entrance ramp at 119th Street for three months

The intersection of Mahaffie Street and Old Highway 56 will stay open, city officials said.

Major disruptions years away

The most significant impacts to local traffic won’t come until the city’s portion of the project reaches its final phase in 2029.

That phase, which is when the interchange will be rebuilt, includes reconstructing Santa Fe Street and extending Rogers Road.

During that time, Santa Fe will close completely.

This is the city’s largest-ever infrastructure project. Olathe’s $40 million portion of the project will be funded through general obligation bonds. KDOT and federal grants will cover the rest.