-Morrison  

 

MORRISON BRIDGE

A Legacy Project Bridge

Morrison at Night

      LIGHTING DESIGN UPDATE

Ed Slavin of Northern Illumination Co. has led WLB's efforts to upgrade the system of lights on the four Morrison Bridge pier faces. Replacing the 16 floodlights with 32 light-emitting diodes (LEDs) reduces energy use by 7/8 and allows a wide range of colors to be programmed via computer. WLB will purchase “green” energy to run the LEDs.

The upgrade also vastly reduces risk and costs of maintaining the color system by improving access to the pier fixtures and eliminating the theatrical gels which provide the color to the current system. The new fixtures will be hung from brackets, rather than fixed to the bridge. This will allow them to be swung up to the deck for maintenance—no more sending workers over the side to clean them or replace bulbs and colored filters.

Installation is expected to be complete by Valentine’s Day 2007.

The energy efficiency and use of alternate power for the upgrade so pleased Pacific Power that is donated $50,000 to the project. An anonymous donation on behalf of WLB volunteers launched the upgrade efforts.

Craig Marquardt, a local lighting designer working at PAE Engineering at the time, did the original design for the Morrison lighting system, including white floods to outline the metal trusses which support the bridge’s outer spans and the center bascule (lift) sections. Those white floods are seldom used now due to access difficulties.

Cost of the fixtures and labor to install that 1987 system were donated by the International Brotherhood of Electrical Workers and the National Electrical Contractors Association.

BRIDGE FACTS

Type: Steel Double-Leaf Strauss Bascule
At mile marker: 12.7
Overall length: 760'
Owner: Multnomah County

   The Morrison was Portland's first bridge and operated as a toll bridge. The current design is the third bridge at this location. Both of the previous structures (1887 and 1905) were swing spans. Design work for this six-lane, three-span, steel deck truss bridge began in 1928; it was built for $12,841,256 and opened in 1958. It is the last moveable bridge built on the Willamette in Portland. Like Morrison St., it was named for a Methodist mssionary from Scotland who built the first house on that thoroughfare.


       The Morrison is structurally like the Burnside, but without ornamentation in its railing or its pair of bridge houses (also mounted on the south face). It serves as a major travel corridor link between SE Portland and inner-city Portland and to Interstate 5 on the north.


       When river traffic requires that the bridge open, a controller inside the western bridge house operates a rack and pinion system and gears 36 feet tall. They lift the Morrison's double-leaf bascule (each 150 feet long) by means of counterweights, one for each side. Even though the roadway's open metal grating reduces its weight and allows quick run-off of rain, the counterweights must each weigh 950 tons in order to balance the bascule halves; the mechanism must maneuver the bascule and counterweights safely up and back in place.

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