A confounding factor is that I think they have changed the typical operating speeds in many parts of the BART system over the years. Also, it isn't like the en

A confounding factor is that I think they have changed the typical operating speeds in many parts of the BART system over the years. Also, it isn't like the entire system is made up of 40-50 year old, original parts. Train cars, wheels, sections of rail, and maybe even bits of rail-bed have been added to the system, renovated, and/or replaced over the years. Qualitatively, I think that I have experienced similar painful noises in every decade since the late 1970s, when I was a little kid and my father worked for BART. In the early 1990s, I can remember people talking about how they sometimes got a quiet train or a loud train on a familiar commute. We had similar observations about different road surfaces put down by Caltrans. I tend to ride it at least once every 2-3 years during return visits. Also, at various places in the East Bay, weather depending, you can hear the early morning trains on at-grade or above-grade track from quite far away. I have heard very similar noises in recent years when visiting the same places, giving me a nostalgic kick as it sounded so familiar.