Our previous post SacCity Truxel Bridge meeting estimated a width of the Truxel Bridge with light rail and walking and bicycling facilities at 57 feet. Looking back to the Green Line to the Airport Transitional Analysis Report (2010-11), it includes the graphic below showing the preferred bridge cross-section that would initially have only one light rail track. The document does not provide measurements for the individual elements nor an overall measurement. It does have an appendix, ‘Appendix B: American River Bridge Technical Memo’ which probably does have this information, but we have not so far been able to obtain a copy. Note that the report is based on but updated from the DNA Final Environmental Impact Report (the Green Line was called Downtown-Natomas-Airport or DNA).

As an estimate, this bridge would be 46 feet wide, less than half the width of the city’s alternative 3B.

The width of the bridge of course affects the cost of the bridge. Materials are only one cost, construction is the other cost. Using the city’s estimate of $227M for alternative 3B, the cost of the SacRT light rail, walking and bicycling bridge might be $140M, a tremendous difference. There would also be much higher maintenance costs if private motor vehicles are included. Private motor vehicles of course include heavy semi-trucks that cause many times the damage of personal vehicles. We have not heard that the city intends to restrict the type of private motor vehicles on the bridge.

Of course the impact on the American River Parkway of the bridge abutments and supports would be about double for the wider bridge with private motor vehicles. A bridge with private motor vehicles adds a pollution burden to the parkway which is absent with a light rail bridge.

The report describes the bridge as:

A. American River Bridge

Significant cost savings were identified for the American River Bridge by changing the assumed bridge type from a cast-in-place segmental bridge to a precast concrete girder or steel girder bridge. These bridge types make use of the construction road necessary to construct the bridge foundations and bridge columns. The disadvantage is that significantly more of the construction activities depend on non-flooded conditions in Discovery Park and rely on the assumption that a sensitive species will not decide to build a nest near the construction site. Alternatively, since the last study was completed, structural engineers have discovered ways to design pre-cast segmental bridges to meet California seismic requirements. For a 20 percent or a $7.5M increase in bridge cost, the flood or biological risks associated with the superstructure construction could be eliminated, which is still a significant cost savings over cast-in place segmental.

The American River Bridge would be designed and built to ultimately carry northbound and southbound tracks. Initially it would have a single track on one side of the bridge, and the other side would have a sidewalk and a northbound and a southbound bike lane. The single-track bridge will support 15-minute train service. Long term, if a roadway bridge is built nearby, the bike lanes and sidewalk could be provided on the roadway bridge, and the LRT bridge could be double-tracked.

• Truxel Bridge