County engineers report good bridge deck ratings, debate capacity standards as severe crash rate rises

Mark Peterson, county engineer, and Justin Hirsch, assistant director for Road and Bridge, briefed commissioners July 21 on transportation performance measures and safety trends.

Peterson said the county follows a standard that compares traffic volume to road capacity. He warned that the newest Highway Capacity Manual gives higher capacity values to some narrow, two‑lane mountain roads than earlier guidance, which will raise the computed percent of roads providing "free‑flow" capacity when the county recalculates measures for the transportation plan. "We've potentially given those roads credit for double the capacity," Peterson said, noting the change is a national standard the county will use but that it may not reflect local driving conditions on steep, narrow routes.

On bridges, Peterson said the county tracks deck area…