Springfield council keeps temporary speed cushions on Centennial after pilot shows lower speeds but local diversion

Springfield — City staff recommended keeping temporary speed cushions installed on Centennial Boulevard after a year-long pilot showed notable speed reductions but also redistributed traffic onto nearby local streets.

Transportation Planning Engineer Michael Liebler told the City Council that ‘‘Before the traffic calming, the average speed was 34 miles per hour with a 80 fifth percentile speed of 37.’’ After the cushions were installed the ‘‘average speed…was found to be 25 miles per hour with an 80 fifth percentile speed of 30 miles per hour,’’ he said.

The pilot — installed in 2024 on Centennial between 21st and 28th streets — used pinned rubber speed cushions and was analyzed with before-and-after counts. Liebler reported weekday volumes on Centennial declined from about 7,500 vehicles to roughly 5,800, while adjacent J Street showed a weekday increase of roughly 21–23 percent and a Saturday increase around 46 percent; staff cautioned percentages can overstate changes on low-volume local streets because the absolute increases were far smaller.

Brian Common, who introduced the item, said the program began after a 2022 petition from roughly 80 residents asking for speed reduction and that staff sought a conservative pilot on a higher-volume arterial before taking broader action.

Councilors pressed staff on trade-offs. Councilor Blackwell voiced concern about the increase in traffic near an elementary school and asked whether the council ‘‘know why’’ a petitioner changed their mind; staff said complaints included noise, vehicle wear and debris from trailers and that one petitioner cited noise as the reason. Deputy Chief (police) told the council ‘‘It’s really hard to affect speed in a residential or commercial neighborhood without regular enforcement,’’ stressing that engineering, education and enforcement must work together.

Several councilors asked whether softer or permanent measures were considered. Staff replied cushions were chosen because they were the fastest option to install; permanent asphalt installations would be smoother for vehicles. Staff also noted alternatives such as speed-feedback signs and tactical urbanism elements (trees, parking adjustments, curb extensions) that could be considered in longer-term plans, although signs often require enforcement backing to sustain their effect.

The council did not vote to remove the cushions. Instead members signaled support for leaving the temporary cushions in place while continuing outreach and evaluation, and asked staff for a more detailed council briefing memo on: the corridor’s functional classification, the Traffic System Plan context, distributional speed data (speed distributions before and after), and policy implications of changing an arterial to a neighborhood street before additional installations.

What’s next: staff will return with the requested briefing memo and continue public outreach and monitoring. The council also signaled openness to installing the originally planned additional cushions between 18th and 21st streets after reviewing the memo and community feedback.