CRC Week: RC-7 to RC-12 the Supplemental Bridges

The second batch of projects to discuss are the supplemental freeway bridge concepts. Like the replacement bridges, they could be located either immediately east or west of the existing bridges, and come in three height variations: Low (65 foot verical clearance), Medium (110 foot vertical clearance) or High (130 foot vertical clearance).

You can find detailed descriptions on pages 5-5 to 5-7 and 5-11 to 5-12 (PDF 279K) from the screening report (PDF 3.3M).
The Low variations would not allow clearance for all river traffic, so they would require some kind of movable span.

In the supplemental scenario, one or both of the existing I-5 bridges would remain in service. What I find interesting about this assumption, is that the analysis does not say what would need to be done to the existing bridges to keep them in service – while in the muti-modal supplemental bridge (RC-22) to be discussed later, there is considerable discussion of how hard it is to retrofit the existing bridges. Hmmm…

As with the replacement bridges, the High versions have airspace problems. In this case, the upstream Mid-level bridge also has an airspace problem since its high point would need to align with the high point on the existing bridges.

To our supplemental question about how these options impact reliance on SOV automobilies, I think the answer is the same as for the replacement bridges: it depends on how you manage the lanes.

Read the Ground Rules for CRC Week.

ID NAME Q1 Q2 Q3 Q4 Q5 Q6 Overall
RC-7 Supplemental Bridge, Downstream, Low-level, Movable P P P P P P P
RC-8 Supplemental Bridge, Upstream, Low-level, Movable P P P P P P P
RC-9 Supplemental Bridge, Downstream, Mid-level P P P P P P P
RC-10 Supplemental Bridge, Upstream, Mid-level P P P F P P F
RC-11 Supplemental Bridge, Downstream, High-level P P P F P P F
RC-12 Supplemental Bridge, Upstream, High-level P P P F P P F

The second batch of projects to discuss are the supplemental freeway bridge concepts. Like the replacement bridges, they could be located either immediately east or west of the existing bridges, and come in three height variations: Low (65 foot verical clearance), Medium (110 foot vertical clearance) or High (130 foot vertical clearance).

You can find detailed descriptions on pages 5-5 to 5-7 and 5-11 to 5-12 (PDF 279K) from the screening report (PDF 3.3M).
The Low variations would not allow clearance for all river traffic, so they would require some kind of movable span.

In the supplemental scenario, one or both of the existing I-5 bridges would remain in service. What I find interesting about this assumption, is that the analysis does not say what would need to be done to the existing bridges to keep them in service – while in the muti-modal supplemental bridge (RC-22) to be discussed later, there is considerable discussion of how hard it is to retrofit the existing bridges. Hmmm…

As with the replacement bridges, the High versions have airspace problems. In this case, the upstream Mid-level bridge also has an airspace problem since its high point would need to align with the high point on the existing bridges.

To our supplemental question about how these options impact reliance on SOV automobilies, I think the answer is the same as for the replacement bridges: it depends on how you manage the lanes.

Comments have been closed and will be submitted to the project public record. If you have additional thoughts, please comment on the open thread for this purpose.

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