Easily
identified by the flags it supports on its rainbow arch 381 feet above
water level, the Fremont Bridge is also impressive because of its
design and size. It is both the longest bridge in Oregon and the longest
tied-arch bridge in the world.
Its
design and construction processes were also remarkable. Oregon Dept.
of Transportation, hoping to avoid the negative public reaction its
Marquam Bridge received in 1966, invited the Portland Art Commission
to give conceptual input. Various public and private firm engineers
collaborated on its high tech, computer-aided design. Engineers from
all over the world came to watch the completion of its assembly, a
record-setting bridge lift: Over a 50-hour period 8 hydraulic jacks
at each corner hoisted the 902 foot-long, 6,000-ton center span arch
up into place 175 feet above the river.
The
Fremont opened in 1973. Its concrete lower deck (for eastbound traffic)
is suspended from the upper (westbound) deck, which is made of steel
plate and designed with strengthening properties in two directions
(“orthotropic”).
The
bridge is named for the street which was to have been its eastside
approach; the street is named for John Charles Fremont who was paid
to survey the Oregon Trail.