By Robert J. Wills, P.E., Vice President, Construction Market Development
Steel Market Development Institute, a business unit of AISI
As a beginning point of the Historic Columbia River Highway, the Sandy River–Jordan Road Bridge at Troutdale, Oregon, proudly welcomes visitors to the Columbia River Gorge National Scenic Area. More than two million visitors arrive here each year, one of the nation’s most frequently visited natural attractions and an entryway to the Portland metropolitan area.
The Sandy River-Jordan Road Bridge is the oldest state-owned metal truss bridge in Oregon. Over the years, it has sustained its fair share of unwelcome encounters with oversized vehicles and concerns over its live load capacity. It has stood the test of time with repairs along the way, but with increasing traffic demand, it became clear that the bridge’s narrow roadway needed reconstruction.
As the owner, the Oregon Department of Transportation (ODOT) is including reconstruction of this bridge as part of its I-84 Corridor Strategy to repair or replace 21 spans through the Gorge with a new generation of bridges. Guidelines governing the design elements for this ambitious project are strict, ensuring that the bridges enhance the natural beauty of the area. The guidelines cover everything from abutments to railings to landscaping to wildlife crossings. The I-84 Corridor Strategy is part of a cooperative area enhancement that is bringing together public and private agencies like ODOT, the city of Troutdale, the U.S. Forest Service, the 40 Mile Loop Land Trust, and others.
The project calls for two bridges to be replaced. The new bridges will be wider than the original, with 200- and 220-foot spans, a rock façade and decorative pylons. The pylons at the gateways to the bridges will be 12-feet high, 6-feet wide and 4-feet deep at the top. Each bridge will be painted dark gray with dark brown trim. The eastbound bridge will include a combined crossing for pedestrians and bicyclists. The project, estimated at $70 million to $80 million, will be funded with a mix of federal and Oregon Transportation Investment Act funding, and will take four years to complete.
ODOT’s Major Projects Branch is in charge of administering the project, which is currently in the design stage. The foundations were originally designed to support a concrete bridge for earthquake conditions. The foundations were large and deep because of the poor seismic performance of the foundation soils.
“For the redesign, we decided to use steel girders instead of concrete for design and cost efficiencies,” said Steve Narkiewicz, consultant project manager for ODOT’s Major Projects Branch. “Steel allowed us to reduce the size of the columns and drilled shafts for the foundation, resulting in a lighter superstructure and providing less disruption to the waterway and fish habitat. We are allowed only six weeks for in-water construction work per year to protect wildlife and the health of the river. Our primary concerns were cost and the impact of construction on the environment, and steel provided the solutions that met our requirements.”
Narkiewicz added that he likes working with steel “because it’s simpler to construct and erect, and it’s attractive.” He would have liked to use weathering steel for the Sandy River–Jordan Road Bridge project, but was restricted by the color requirements necessary for compliance with the I-84 Corridor Strategy guidelines.
For the redesign, the ODOT Major Projects Branch selected a contemporary design using a modern, box girder superstructure. ODOT’s Type, Size and Location (TS&L) Report calls for bridge girders that are haunched in a parabolic shape to create an arch-like form. The interior piers consist of two-column bents with textured rock surfaces created using formliner on two faces. The columns are connected by a cap beam with a haunched bottom surface to complement the haunched girder shape. The column shapes are tapered to match the shape of the pylons at the ends of the bridge. The pylons and the bridge abutment surfaces both will have a textured rock surface, created using formliner. The bridge railing sports an open design to avoid restricting the viewpoint of motorists and to provide continuity with other bridges in the Gorge. The pedestrian railing is also an open design, with vertical pickets and a curved element to continue the arch theme.
The haunched steel box sections will be continuous and composite with the concrete deck. Three boxes, spaced at about 22’-0”, will be used for the westbound bridge, while four boxes, spaced at approximately 20’-6”, will be used for the eastbound bridge. The deck slab overhang distance will be approximately 4’-8”. The depth of the boxes will vary from about 5’-6” at mid-span to 11’-0” at the interior bents. The box webs will be vertical.
The recommended span arrangement is 200’-220’-220’-200’, for a total bridge length of 840 feet. This spacing will provide a clear span over the current thalweg and a greater overall hydraulic opening to improve fluvial performance, while avoiding existing bridge foundation units. The end bents are outside of the Ordinary High Water boundaries. On the east side, existing fill will be removed from within the regulated area within the Ordinary High Water boundaries in some locations, while in other locations (mainly on the south side) some fill from the embankment end slope and side slope will spill into the regulated area. It is expected that the fill volume removed from the regulated area will exceed the additional fill volume that is placed.
The box girder haunch depth will vary over a length approximately 50 feet each side of the interior bents. The box girder depth will be constant in the mid-span regions between the variable depth sections and also at the end bents. Field splices will be provided between the variable depth sections and constant depth sections. An additional field splice will be provided in each end span. Top flange lateral bracing will be required to provide stability for the box tub until the deck slab is in place.
Pinned bearings will be used at each interior bent so that the bents will share in carrying the longitudinal seismic loads. Expansion bearings will be used at the bridge ends. The maximum girder weight is around 120,000 pounds.
The revised bid-let date is February 2010, with construction expected to begin in the spring of 2010. The targeted completion date is August 2013.
The completed Sandy River–Jordan Road Bridge project will provide a safe, scenic and environmentally responsible steel design solution that will benefit all creatures living both above and below its spans.
Bridge: Sandy River–Jordan Road Bridge
Location: Troutdale, Oregon
Expected Start Date: Spring 2010
Targeted Completion Date: August 2013
Bridge Owner: Oregon Department of Transportation
Bridge Designer: David Evans and Associates, working as a subcontractor to the Oregon Bridge Delivery Partners
Specifications: Total Bridge Length: 840 feet
Width: 200- and 220-foot spans
Construction: Haunched steel box sections will be continuous and composite with the concrete deck
Façade: Rock façade and decorative pylons
Pylons: Pylons at the gateways to the bridges will be 12-feet high, 6-feet wide and 4-feet deep at the top
Finish: Painted dark gray with dark brown trim
Cost: Estimated at $70 million to $80 million
Funding: A mix of federal and Oregon Transportation Investment Act funding