Roundabouts or potholes? What the numbers say as a McLane Point Nextdoor thread heats up

A McLane Point neighbor's Nextdoor post arguing that the state spends too much on roundabouts and trails while roads go unrepaired has drawn 175 reactions and 190 comments since Saturday. The top reply pushed back: roundabouts cost about the same as stoplights, it said, but need no electricity and only routine upkeep.

Here's what public data say about both claims.

Building cost. The Washington State Department of Transportation says the cost of building a roundabout and building a traffic signal is "pretty comparable." Costs vary by site, especially when land has to be bought.

Running cost. WSDOT says roundabouts eliminate the hardware, maintenance and electrical costs of traffic signals, which can run $5,000 to $10,000 per year. The agency's design manual says roundabouts last longer than signals, need less maintenance of electronic equipment, and keep working during power outages. Roundabouts still need lighting, signs and pavement care.

Safety. WSDOT says roundabouts typically bring a 37% reduction in overall collisions, a 75% reduction in injury collisions and a 90% reduction in fatal collisions. Under its "Roundabout First" policy, roundabouts are encouraged at certain intersections.

Where repair money comes from. In local budgets, intersection projects and paving don't simply trade off dollar for dollar. Thurston County's 2026-2031 Transportation Improvement Program estimates about $29.3 million in road fund revenue for 2026 against about $33.3 million in planned spending, drawing on a starting balance of about $12.8 million. The county set aside $2.5 million for its pavement preservation program. The same plan includes a roundabout at SR 507 and Vail Road SE and intersection work at Johnson Point Road and Hawks Prairie Road.

The open question. Whether the overall balance between new projects and upkeep is right is a fair debate. The figures above don't settle it. Residents can comment on the county's transportation plan when it is updated each year, and report potholes on county roads to Thurston County Public Works.