Helena considers $30 million roundabout for Custer, Henderson intersection

Helena is again looking at the Custer Avenue and Henderson Street intersection as one of its most stubborn traffic choke points, and this time the price tag is big enough to signal a long-term fix. The latest estimate puts a roundabout at roughly $30 million, a figure that underscores how much congestion, safety and future growth are wrapped into one busy corner near downtown.

The Montana Department of Transportation says the Custer Avenue project is still in early phases, even as traffic volumes rise and congestion hits during peak times. MDT, the City of Helena and Lewis and Clark County already prioritized improvements to the corridor in the city’s long-range transportation plan, and agency materials include traffic simulations showing current conditions and projected 2027 traffic if nothing changes.

The intersection has been part of Helena’s transportation conversation for years. In March 2022, city transportation systems director David Knoepke told the Helena City Commission that the corridor mattered to the city and that planners wanted it to feel like an urban street, not a highway. At that point, an MDT feasibility study had estimated $20.7 million for improvements between Montana Avenue and Benton Avenue, with $20.4 million potentially available through federal urban road funding.

By March 2023, city transportation planning records still listed the Custer Avenue project in an “Other” phase while staff evaluated reconstruction options between Montana Avenue and Henderson Street. Those records pointed to a 2028 construction target and laid out the issues under review: safety, capacity, boulevards, bike and pedestrian access, environmental concerns and geometry. The city’s review also involved a technical design committee with representatives from MDT, the Federal Highway Administration and the city.

The roundabout idea has not gone uncontested. Public comments to MDT warned that a circle could slow traffic on an already busy corridor, while others argued that Helena needs broader fixes, including railroad underpasses at Benton and North Montana, because some drivers use Custer to reach Henderson. That wider system problem has remained central as the city weighs whether to treat this as a standalone intersection project or part of a larger movement plan.

In May 2026, Helena also sought an $8 million federal implementation grant that could help pay for two shovel-ready roundabouts, one at Custer and Henderson and another at the downtown five-way intersection known as Mini-Malfunction Junction. Together, those efforts show the city is pushing past study mode and into funding and design work, but the question remains whether the next investment will finally relieve a corridor that already shapes how people reach downtown, nearby neighborhoods and event venues.