INTERSTATE BRIDGE

The 'Interstate Bridge' (also 'Columbia River Interstate Bridge') is a pair of nearly identical steel through truss bridges with a vertical lift that carries Interstate 5 traffic over the Columbia River between Vancouver, Washington, and Portland, Oregon, in the United States. First opened to traffic in 1917 with a second span opening in 1958, the bridge handles 124,500 vehicles (as of 2004).^[1]
The green structure, which is over 3,500 ft (1000 m) long, carries traffic over three northbound lanes and three southbound lanes.

Contents

First bridge

Upgrades

Replacement

References

External links

First bridge

The bridge was built to replace an overcrowded ferry system operated by Pacific Railway, Light & Power Co. Construction on the bridge began in March 1915, following the sale of bonds.^[2] The first bridge was opened on February 14, 1917 at a cost of $1.75 million, which was shared between Clark County and Multnomah County.^[3] Clark County paid $500,000 with Multnomah County paying $1,250,000.Horner, John B. (1919). "Oregon: Her History, Her Great Men, Her Literature". The J.K. Gill Co.: Portland. The first bridge has a total of 13 steel spans with three measuring 275 ft (84 m) in length while the remaining ten spans are 265 ft (80 m) long. One of the 275-ft spans is the lift span for allowing river traffic by the bridge. The original paved roadway was 38 ft (12 m) wide and had a 5-ft (1.5-m) wide sidewalk. At the time it was the only automobile bridge across the river between Washington and Oregon. It was originally a toll bridge costing $.05 per person.

Upgrades

In 1958 a $14.5 million upgrade created a southbound span and doubled the capacity of the bridge. The new bridge was built with a "humpback" that provides 72 ft (22 m) of vertical clearance and minimizes bridge openings. At the time the new bridge was opened, the old one closed to give it the matching humpback. When both bridges were opened in 1960, tolls were reinstated at $.20 for cars, $.40 for light trucks, and $.60 for heavy trucks and buses, before being permanently removed in 1966.
A $3 million upgrade to the lift cables, expansion joints, and a deck repaving was completed in 1990. The diesel generator used to power the lift was replaced in 1995 at a cost of $150,000. In 1999 the bridge was repainted at a cost of $17 million. A $10.8 million electrical upgrade was completed in mid-May of 2005. ^[4]
The bridge is 3,538 ft (1,078 m) long with a main span of 531 ft (162 m).^[5] The vertical lift provides 176 ft (54 m) of clearance when opened. The lift takes 10 minutes to open and does so between 10 and 20 times per month. In 2001 the 6 lanes of the bridges carried 120,000 vehicles including 10,000 trucks, operating at capacity for four hours every day. ^[6]

Replacement

Currently, many traffic engineers consider the bridge to be obsolete, both due to its age and its limited capacity. The bridge is frequently a bottleneck which impacts both traffic on the freeway, as well as on the river. The Oregon and Washington state departments of transportation are jointly studying how to replace the bridge. The estimated cost for a replacement bridge is around $2 billion.^[7]
A replacement (especially a fixed span bridge) is complicated by a railroad drawbridge crossing the Columbia a short distance downriver, which constrains the location of the shipping channel; and by approach paths to Portland International Airport in Portland and to Pearson Field Airport in Vancouver, which limit the height of any new structure. Some have proposed replacing the bridge in a different location. There are presently 12 transportation plans that are being studied to improve and expand the Interstate 5 crossing of the Columbia River. ^[8] In late 2006, 2-4 of these plans will be selected for a final proposal. ^[6]
There is also a long standing debate as to whether or not a new bridge would include a MAX Light Rail line, express buses or bus rapid transit. During his 2007 "State of the City" address, Vancouver mayor Royce Pollard stated

Picture of the bridge in 1917-1919.

References

1. Average Daily Traffic on Oregon’s Interstate Highways 1954–2004
2. Spanning Washington : Historic Highway Bridges of the Evergreen State, , Craig E., Holstine, Washington State University Press, , ISBN 0-87422-281-8
3. The Portland Bridge Book, , Sharon, Wood, Oregon Historical Society, , ISBN 0-87595-211-9
4. Interstate Bridges Electrical Upgrade
5. Historic Highway Bridges of Oregon, , Dwight A., Smith, Oregon Historical Society Press, , ISBN 0-87595-205-4
6.
7. Columbia bridge advice: Scrap the old, build new James Mayer
8. Preliminary Alternative Packages
9.

External links

★ WSDOT:Interstate Bridge

★ ''Columbia River Crossing: Home page of ODOT/WSDOT project to replace the Interstate Bridge''