Next, we move on to a more complicated diagram that represents the blended system in general, including the Caltrain modernization project. The derived attributes at the ends of the requirement tree are highlighted in green. If you delete any of the green boxes, all of the boxes that depend on it above are negatively affected.
For example, if you delete level boarding, then you can't reduce station dwell times, which means you can't increase Caltrain average speeds enough to allow operating peak hour traffic, which in turn means the blended system won't work well, and HSR may need to build four tracks all the way.
For another example, if you delete train doors that work at the same height as HSR, then Caltrain can't share platforms with HSR, which means bigger stations and limited capacity at SF Transbay, so Caltrain won't be able to run all trains into the downtown core, which in turn will hurt Caltrain ridership and increase congestion on highway 101 and I-280.
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