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ODOT Cannons Keep Birds off Bridge

Thursday, January 15, 2015

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Oregon bridge crews are using propane-powered cannons to shoo birds from an interstate lift span—a non-lethal way to discourage starlings from roosting on the bridge.

Each fall and winter, thousands of starlings migrate to the Portland area, and they have become fond of making a home out of the I-5 Interstate Bridge. However, the mess they leave behind corrodes the structure's steel lift spans.

"Bird droppings coat the bridges, the catwalks, the roadway, vehicles, bicyclists and pedestrians. The droppings are acidic and speed corrosion of the steel and are unhealthy, unsafe, unsightly and unpleasant for workers and bridge users," the Oregon Department of Transportation said.

This 2012 ODOT video shows how the agency uses the cannons to deter starlings from roosting on the bridge.

The Interstate Bridge is a pair of nearly identical steel vertical lift, through-truss bridges that carry Interstate 5 over the Columbia River, connecting Portland and Vancouver, WA. The first bridge opened in 1917, and the second in 1958. The 3,500-foot-long bridges see about 130,000 vehicles each day.

'Purge These Pests'

After years of trial and error, ODOT realized that booming orchard cannons seem to work best for keeping the birds away.

"During the past 25 years, maintenance crews have tried virtually everything that seemed even remotely reasonable to purge these pests: noisemakers, loud banging on the structure, chemical applications and sharp-edged moldings, to name just a few," ODOT said.

The cannons started Wednesday (Jan. 14), and will be used again Jan. 30 and Feb. 11. On each of the three days, they run for about one hour in the late afternoon and early evening. The blasts can occur as often as once every 2-3 seconds.

The noise from the cannons stresses the birds, upsetting their biorhythms and causing them to seek out a better place to roost, ODOT explained.

The birds almost immediately move away from the lift spans and settle in nearby trees.

Dramatic Reduction

While ODOT wishes it could completely remove the birds from the bridges, realistically, significantly reducing the numbers is the goal.

Interstate Bridge
CC BY-SA 2.5 / / Cacophony

The Interstate Bridge is a pair of nearly identical steel vertical lift, through-truss bridges that carry Interstate 5 over the Columbia River, connecting Portland and Vancouver, WA.

This year, a "dramatic" reduction in starlings using the bridge has already been seen, ODOT said. In 2012, the agency counted 2,000 to 3,000 birds roosting on the bridge—a steep decline from the 30,000 counted in the past.

"Obviously the lift spans play a crucial role for both Interstate 5 traffic and marine traffic. Ensuring the bridges operate smoothly and that ODOT personnel are able to work in a safe and healthy environment is our paramount concern," ODOT said.

Each cannon cost about $1,000 and uses two gallons of propane. Some years, ODOT has used as many as seven cannons, and the timing and placement on the bridges varies from year to year. 

At 95 decibels, the noise level is about the same as vehicle traffic, according to ODOT.


Tagged categories: Bridges; Corrosion protection; Department of Transportation (DOT); Environmental Controls; North America; Steel

Comment from M. Halliwell, (1/15/2015, 10:58 AM)

Well, if it works (almost all the time) for the oil sands tailings ponds, why not for bridges? I'm glad they are keeping the overall volume down...otherwise the neighbours wouldn't be appreciative.

Comment from Chuck Pease, (1/15/2015, 2:40 PM)

How long before a animal rights group gets wind and starts to cry foul about interrupting the starlings biorhythms. I can almost imagine the headline.

Comment from Noel Stampfli, (1/15/2015, 5:21 PM)

Seems like a good solution to a very serious problem. I am curious about how USFWS feels about it. I am under the impression that unlike some species, Starlings are considered sufficiently pest like that they do not enjoy protections under the Migratory Bird Act or other statutes protecting nesting birds. Then again I am not a bird person.

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