PIERRE, S.D.(HubCityRadio)- Starting this past Monday, the speed limit from Bath Corner to Aberdeen on US HWY 12 was lowered from 65 to 55mph.

The request to make changes to the speed limit went to the South Dakota State Transportation Committee back on June 26th.  Aberdeen Regional Transportation Engineer Matt Dorfschmidt submitted the following request:

“The proposed change would extend the current 55 mph speed limit east of Aberdeen through the intersection at Bath Corner.  This recommendation follows a recent construction project that altered the lane configuration in this area, changing from a four-lane divided section to a five-lane undivided section. Since this lane configuration is new, recent crash data is not yet available to include in the department’s evaluation.

Four speed studies were conducted on January 29, 2025, at two locations along the corridor. One near 393rd Avenue and the other near 395th Avenue (Bath Corner) in each the eastbound and westbound directions. Each study involved over 200 vehicles and was conducted under dry conditions.

Across all locations, the 85th percentile speed was consistently 67 mph, with average speeds ranging from 62 to 65 mph. Most vehicles were traveling in the 60–70 mph range.

With the new lane configuration, the department classified this segment of highway as a developed urban principal arterial for analyzation using the NCHRP 17-76 Speed Limit Setting Tool. This tool advises that speed limits in these settings should not exceed 55 mph.

Although speed studies show that the 85th percentile speeds are around 67 mph, the engineering judgment supported by national standards prioritizes road context and safety over matching prevailing speeds.

The speed study was requested by the Aberdeen Region Engineer as a result of concerns raised by businesses and concerned citizens that use the highway in this location. The Aberdeen Region Engineer concurs with the recommendation.

Captain Randi Erickson of District One of the South Dakota Highway Patrol, Brown County Sheriff Dave Lunzman, and Aberdeen Police Chief Dave McNeil have been contacted and concur with the recommended speed reduction.”

The Commission approved the request and submitted it to the Secretary of State’s Office in July.