Sumner staff push for roundabout design at Tacoma–Puyallup intersection, request $210,523 for additional consultant work

Sumner City staff asked the City Council to authorize additional design work and a consultant agreement as they pursue a roundabout at the Tacoma Avenue and Puyallup Street intersection.

The presentation, led by a project presenter and Public Works Director Michael Khosa, described the project as construction of a roundabout plus Americans with Disabilities Act (ADA) curb-ramp upgrades, sidewalk widening and an overlay of approximately 0.25 miles of Tacoma Avenue pavement to extend service life. Staff said the project is intended to improve traffic flow, reduce congestion and enhance safety for pedestrians and other road users.

The consultant’s traffic study compared a roundabout and a traffic signal under projected future traffic conditions. “Roundabouts give higher level of service,” the presenter said, and the consultant’s modeling showed the roundabout would maintain a Level of Service A with an average delay of about 9.2 seconds, while a signalized intersection would degrade to a much higher average delay (the presentation cited an average delay of 92 seconds for a signal). The staff presentation also listed environmental and right-of-way factors that would require more design work for a roundabout than for a signal.

Why it matters: staff said a roundabout can reduce delay and collision severity, lower long-term maintenance costs compared with signalized controls and, on the consultants’ numbers, slightly reduce total project cost. The presentation showed the design phase is currently funded through PSRC (the Puget Sound Regional Council) but right-of-way and construction are unfunded. Staff estimated a preliminary construction cost for the signal option at about $2,280,000 and for the roundabout at about $2,190,533 — roughly $89,000 lower overall for the roundabout after accounting for phases shown in the slide deck.

Environmental permitting and costs: Michael Khosa explained that because of federal funding attached to the project, a roundabout would trigger a broader NEPA-type environmental review and additional permitting steps beyond an overlay or signal option. “Once you start to get into something like this, we’re essentially changing the whole intersection… we will go over the threshold for the need to go through an environmental permitting process, because of the federal funding we have in place,” Khosa said, adding that the review could require stormwater treatment or detention measures if impervious surface is replaced.

Right-of-way and truck geometry: staff said roundabout footprints typically require small permanent or temporary right-of-way takes (staff described “very minor, right-of-way acquisitions, very minor little strip takes, you know, 5 feet, 10 feet”) and that additional acquisition maps and legal descriptions would be needed. Designers also noted heavy truck traffic in the corridor and the need for turning‑vehicle simulations; staff said a truck apron would allow large semis to negotiate turns and that durable surfacing would be provided for aprons to avoid early deterioration.

Budget request and next steps: staff asked council to authorize a consultant agreement amendment in the amount of $210,523 to fund additional roundabout design effort, including advanced traffic modeling, environmental permitting support, right‑of‑way mapping and noise analysis. Council members asked questions about the nature and cost of environmental permitting, the need for traffic modeling for semis, and service-life and surfacing choices. Council did not take a formal roll-call vote in the study session. Instead, staff said they would “initiate the change order on the design, and then we’ll catch it at a quarterly budget amendment,” indicating staff direction to proceed with the design change and to include the amendment in the next budget cycle.

What remains unresolved: construction funding and right-of-way acquisition costs remain unfunded; staff said they expect to seek construction-phase grants or other funding later. The presentation did not commit to a construction schedule; staff estimated a multi-year timeline and said the design was at about 10–15% complete. The council’s questions and staff responses focused on clarifying environmental triggers, right-of-way needs and freight geometry rather than on the underlying selection of the roundabout versus signal.

Tally of formal actions: no formal motion or recorded vote was taken during the study session. Staff were directed to initiate a design change order and include the consultant amendment in a forthcoming budget amendment.