Interstate Bridge

The Interstate Bridge (also Columbia River Interstate Bridge, I-5 Bridge, Portland-Vancouver Interstate Bridge, Vancouver-Portland Bridge) is a pair of nearly identical steel vertical-lift, through-truss bridges that carry Interstate 5 traffic over the Columbia River between Vancouver, Washington, and Portland, Oregon, in the United States. The bridge first opened to traffic in 1917, as a single bridge carrying two-way traffic, but a second, twin bridge was opened in 1958, and each of these bridges carries only one-way traffic. The original 1917 structure is the northbound bridge.^[1] As of 2006, the bridge pair handles around 130,000 vehicles daily.^[1] The green structure, which is over 3,500 feet (1,067 m) long, carries traffic over three northbound lanes and three southbound lanes. It was added to the National Register of Historic Places in 1982, as the "Portland–Vancouver Highway Bridge".^[3]

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.^[6] 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.^[7] Clark County paid $500,000 and Multnomah County $1,250,000.^[8] The first bridge has a total of 13 steel spans, with three measuring 275 feet (84 m) in length and the remaining ten spans 265 ft (81 m) each.^[8] One of the 275-foot (84 m) spans is the lift span for allowing river traffic under the bridge.^[8] The lift span is capable of moving 136 ft (41 m) vertically,^[5] and provides 176 ft (53.6 m) of clearance below when fully raised.^[1] The towers are 190 ft (57.9 m) tall, above the roadway.^[5]

The original paved roadway was 38 ft (11.6 m) wide and had a 5 ft (1.52 m) wide sidewalk.^[8] It was the first automobile bridge across the river between Washington and Oregon,^[8] and the second to span the river at all, after the Wenatchee Bridge of 1908.^[9] It was originally a toll bridge costing 5¢ per vehicle or per horse and rider.^[5] In 1928 the states of Washington and Oregon jointly purchased the bridge from the counties and discontinued tolling the following year.^[1]

Electric streetcars operated across the bridge from opening day in 1917^[2] until 1940. The bridge's deck carried dual-gauge track,^[5] to accommodate both Vancouver's standard gauge cars and Portland's narrow gauge cars. Before the bridge, Portland had had a "Vancouver" streetcar line since 1893, but it actually only ran as far as Hayden Island, where passengers transferred to a ferry owned by the street railway company, to continue across the river to Vancouver.^[10] Streetcar service across the Interstate Bridge ended on September 3, 1940.^[10]

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 (21.9 m) of vertical clearance and minimizes bridge openings. At the time the new bridge was opened, the old one was temporarily closed for rebuilding to give it a matching humpback section. When both bridges were first open concurrently, in 1960,^[7] each span became permanently one-way only, and tolls were reinstated at $.20 for cars, $.40 for light trucks, and $.60 for heavy trucks and buses, until removed in 1966 after the construction expenses were paid off.^[1][11] 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 2005.^[12]

The bridge is 3,538 feet (1,078 m) long with a main span of 531 feet (162 m).^[13] The vertical lift provides 176 feet (53.6 m) of river clearance when fully opened. Openings last about ten minutes and occur between 10 and 20 times per month.^[14]

Signals for several miles each direction warn of bridge opening since traffic has to stop and wait. Due to this interruption, the Interstate Bridge is one of the Federal Highway Administration's highest priorities for replacement. Commercial river traffic schedules passage to avoid rush hour.

In 2006 the six total lanes of the bridges carried 130,000 vehicles daily.^[1] Full traffic capacity occurs four hours every day.^[14]

Replacement

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. Initially, the estimated cost for a replacement bridge was around $2 billion,^[15] but that number has climbed steadily to around $4.2 billion.^[16]

Design of a replacement (especially a fixed-span bridge) is complicated by the existence of a railroad drawbridge crossing the Columbia a short distance downriver (on the Burlington Northern Railroad Bridge 9.6), which constrains the location of the shipping channel; and by approach paths to Portland International Airport in Portland and to Pearson Field in Vancouver, which limit the height of any new structure. Some have proposed replacing the bridge in a different location. There were originally 12 transportation plans that were being studied to improve and expand the Interstate 5 crossing of the Columbia River.^[17] In late 2006, 4 of these plans were selected for a final proposal, along with a fifth no-build option.^[18] The Columbia River Crossing project's six local partner agencies selected a replacement I-5 bridge and light rail extension to Clark College as the project's Locally Preferred Alternative (LPA) in 2008.^[19]

There is also a longstanding 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

In December 2007, Oregon Governor Ted Kulongoski advocated for a new bridge, publicly endorsing the Oregon Business Plan's proposal.^[21]

In 2008, as fuel prices increased and project cost estimates soared, many in the area began questioning whether the project is worth the costs. In addition, many on the Portland side of the river fear that a 12 lane highway bridge to Vancouver, which has virtually no land use restrictions, will encourage suburban sprawl and development north of the river.^[22]

Further concerns over the 12-lane "Columbia River Crossing" (CRC) proposal include its failure to examine critical environmental impacts, such as damage to Clark County's drinking water supply, endangered fish habitat in the Columbia, and air pollution in North Portland.

In 2008, the Environmental Protection Agency found that the Draft Environmental Impact Statement for the CRC had failed to adequately cover these issues, as well as the potential induced demand for suburban sprawl. In a letter to CRC planners, the EPA wrote that "There was no indication (in the CRC environmental impact statement) of how these vulnerable populations might be impacted by air pollution, noise, diesel construction vehicles and increased traffic", referring to minority communities in North Portland.^[23]

References

External links

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