The Engineer developed four prefabricated self weathering steel truss bridge alternates at two locations that addressed these concerns in various ways.
The two alternates at the south location gave central access to the bike trail and the neighborhood and shorter spans. Both structures had low clearances but provided access ramps into the creek channel for dredging operations to either side of the bridge and preserved the maintenance road along both sides of the creek. An added feature provided a permanent buried culvert along the far bank for use during dredging.
The Alternate 1 - 115 ft long by 5.75 ft tall truss was located so as to avoid an intersecting ditch. POITRA removed a large part of the trail access road to accommodate the dredging ramps, which required restoring the newly exposed creek channel in the photograph.
The Alternate 2 - 125 ft long by 6.25 ft tall truss required a short concrete crossing at the near end to bridge the intersecting ditch. Again removing part of the trail for the ramps required POITRA to restore he creek background beyond.
The past bridge design experience of POITRA principals made the transition from design plan to the finished structures that appear in the visualization seamless and efficient. POITRA illustrated each alternate using combined 3D rendering and traditional digital painting techniques.
To add the truss bridges and abutment walls POITRA modelers built accurate, properly cambered and detailed 3D truss models which were then camera matched to the photograph. The models were then appropriately lighted, rendered and composited with the photograph to create the final photo realistic simulation of the proposed conditions for each alternate.
The simulations were used in meetings between VTA, PGE, the Water District and the neighborhood.