|
Historic bridge gets new weight limit
Rock Point Bridge, built in 1920, is in need of repair, and state engineers have posted a weight limit of 10,000 pounds until work can be done on the span next year. 79-year-old Rock Point arch will get repairs next year By MELISSA MARTIN GOLD HILL -- From a drift boat, the ornate, 113-foot arch of Rock Point Bridge may look as strong as the day it was built in 1920.
But state engineers say the bridge that carries the Old Pacific Highway across the Rogue River is showing its age. The Oregon Department of Transportation recently posted a 10,000-pound weight limit on Rock Point Bridge until repairs can be made early next year."Posting a weight limit on a bridge is not our first option," said Mark Hirota, state bridge engineer in Salem. But after running Rock Point Bridge's statistics through a series of computer programs and math computations, the 79-year-old historic landmark came up short. Bridge engineers say the crossbeams, which support the bridge deck, need to be strengthened. The newly posted weight limit signs warn drivers of trucks, school buses and motor homes -- anything larger than a car or pickup truck -- to take another route, such as the South Gold Hill interchange about two miles away. State highway crews, Jackson County gravel trucks and City of Gold Hill sludge trucks are among those making a detour."It's not a big deal for us; we just reroute to the bridge at Highway 99," said Royal Gasso, Gold Hill public works director."But I have seen some trucks back up and turn around because they are not used to it being posted yet," he said. One of the oldest bridges in Southern Oregon, Rock Point is situated at a pioneer post office site on Highway 234 where Old Stage Road begins. It's about 12 miles northwest of Medford. Rock Point is one of 900 state highway spans designed by the legendary engineer Conde B. McCullough and is eligible for listing in the National Register of Historic Places. "Rock Point Bridge is very characteristic of McCullough's style. It's an ornate, attractive structure and there are not a lot of those remaining in Oregon," said John Vial, ODOT district manager. An even older span is Robertson Bridge, a structure with steel trusses built in 1919 across the Rogue River in Josephine County. The state next year will begin building a $4.5 million new bridge upstream to replace it, Vial said. Another state project closer to home is a $2.6 million replacement for the Cottage Street Bridge in downtown Medford."We have a whole group of bridges in Oregon that have met their design life and will require extensive maintenance and replacement," Vial said. Oregon has 6,473 bridges, 2,630 of them in ODOT's care. Rock Point is among a wave of bridges that are at least 65 years old, built during the Depression. They pose a higher maintenance concern for state engineers, Hirota said. A second wave of bridges, built during the post-war interstate highway era, are at least 35 years old and are predicted to need more maintenance within 20 years, Hirota said. State engineers inspect bridges at least every two years, more frequently if the bridge shows sign of corrosion or old age."If bridges aren't safe, the whole transportation network in the state is compromised and that affects freight, tourism and daily life," Hirota said. For example, the state last year replaced Brush Creek Bridge, built in the 1950s on Highway 101 south of Port Orford. Chunks of concrete from the bridge were falling on a pathway that campers used to get from Humbug Mountain State Park to the beach. "The salt air had taken its toll on the reinforcing steel," Hirota said. "There were pieces of the bridge that had deteriorated to the point where you could see the corroding reinforcing steel." The new bridge is built to last 100 years, with stainless steel reinforcing bars and microsilica concrete designed to keep the salt water out, Hirota said. Engineers are working on repair designs for Rock Point in Gold Hill. They should know by January what strategy they will use to strengthen the bridge. "The weight limit is a short-term fix until we can make repairs and remove the load posting so people can begin using the bridge again," Vial said. "It's still an old bridge that requires care." |
