Portland Courant

The 115-year-old bridge, the first and oldest reinforced concrete bridge in Oregon, can no longer support heavy freight and emergency vehicles 

(May 10, 2023) The Portland Bureau of Transportation (PBOT) is implementing new vehicle weight restrictions on the NE 28th Avenue Bridge over Interstate 84, following a new load rating by the Oregon Department of Transportation (ODOT). Using federal criteria and methodology, as required by regulations, ODOT determined that further weight restrictions are required to protect roadway users and the bridge. As a result, most heavy freight vehicles will no longer be able to use the bridge. 

The NE 28th Avenue Bridge over Sullivan’s Gulch was the first reinforced concrete bridge in Oregon, originally constructed in 1908 at 558 feet long. It’s 16 spans of reinforced concrete girders and floor beams crossed over the ravine, in addition to several dry house and main line railroad tracks. Due to its 115 years of service, it is considered the oldest reinforced concrete bridge in the entire State of Oregon.

Since the original construction, the bridge has been strengthened and modified several times. In 1910, the documented lack of original design and construction quality required strengthening of the girders. The bridge was later partially replaced in the 1950s to make room for the Banfield Freeway below and again in the early 1980s for the TriMet MAX line. Additionally, parts of the bridge had to be strengthened in the 1960s. The bridge has been restricted to legal truck loads for decades now, due to its history and overall condition. Now those restrictions will place even greater limits on the weight of vehicles crossing the span.

Going forward, single unit trucks with four axles or less are limited to a weight of 15 tons, five axles limited to 17 tons, and six to seven axles are limited to 19 tons. Combination trucks like a semi-tractor with trailer are limited to 25 tons and a single unit truck with a trailer is limited to 30 tons. Some examples of freight vehicles that are not allowed include construction vehicles such as dump trucks and concrete trucks (typical weight varies from 27 tons to 39 tons), garbage trucks (26 tons), and semi-trucks with trailers (40 tons).

Emergency vehicles will also be weight restricted, with two axle vehicles limited to 11 tons and 3 axles limited to 15 tons. Fire trucks typically weigh between 28 tons (for two axle trucks) to 43 tons (3 axles). All weight restricted vehicles are advised to use the NE 33rd Avenue Bridge going forward. PBOT has notified emergency responders of this new restriction.

Decades of deferred maintenance and a lack of investment in transportation assets continue to impact Portland’s transportation network. PBOT owns 159 bridges across the city of Portland. Like the NE 28th Avenue Bridge, 47 bridges (approximately 30%) are past their expected lifespan. Early estimates for the cost of a full bridge replacement of the NE 28th Avenue Bridge are in the range of $30 million. There is no current funding in place to rehab or replace the NE 28th Avenue Bridge or other bridges that are past their expected lifespan.

Original source can be found here