Data scientists blog about Caltrain data, come up with convoluted hypothesis about bias in sensors at two stations. Commenter on blog notices that Caltrain is occasionally single-tracking between those stations due to a bridge replacement. [1] "Data science" ends up with a bloody neck from Occam's razor. [1] http://www.caltrain.com/projectsplans/Projects/Caltrain_Capi...
There are a couple of reasons that this isn't the explanation. To pick one, the random data selection in the blog post showed data from October 2015 -- Feb 2016, and this Caltrain link appears to show the bridge work starting Feb 26th, 2016. So, no the just-so story doesn't appear to be just-so.
The data is very much consistent with the bridge work hypothesis. The website indicates a series of bridges are being replaced. Starting 9/28/15 with Tilton Ave. and proceeding northward to Monte Diablo Ave then Santa Inez Ave.