Yesterday, like thousands of other people, I returned home from Washington, D.C. wrapped in the comfort of an Amtrak train.
Somewhere close to Baltimore, MD, the conductor announced, “Due to the excessive heat, we will be 15 minutes delayed at every stop.”  
I couldn’t help notice the confused, annoyed expressions on the faces of my fellow commuters. “What the [beep] does the heat have to do with the train?” I overhead one ask. I had to refrain from quipping, “I heard the trains unionized recently.  Now they’re authorized to take a 15-minute nap for every hour of working in excessive heat.”  I had the good sense to realize that comment would flop (as it just did).
I also realized this: Had the conductor elaborated on the reasons for the heat-related delays, the passengers would have learned a bit about science, politics and the benefits of being an informed citizen. May I elaborate? Dream a bit?
For argument’s sake, let’s say the conductor opted to maximize the impact of his monologue to this (literally) captive audience. Hypothetically, he shares with the commuters the basics of what he knows of the situation (his “local knowledge” as it’s sometimes called):
What: trains are delayed
Why: excessive heat causes overhead electric wires to droop. Trains need to travel at a fixed speed to avoid slicing these line.
Solutions: Short term, travel at reduced speed. Long term, the only way we know to solve this problem is revamp the mechanics of the lines through much of the Northeast corridor so we, like the Europeans, can depend on a reliable, faster mode of public transportation. Particularly of interest these days due to the high cost of fuel and environmental concerns. It’ll cost a ton of money–your tax dollars–to make it happen so if you know of a better solution, share it with us.
Why might Amtrak take this approach? 1) At the very least, it would help soothe the soul. No point getting angry at Mother Nature.  2) Amtrak is subsidized by the federal government. Revamping the lines requires substantial support and financial appropriations from Congress–the folks who manage our federal tax dollars.  The more commuters understand what the problem is and how it can be solved, the more likely they are to voice an informed opinion on this policy issue, if given the opportunity to do so. 3) It’s possible an informed commuter may incorporate his/her own local knowledge (or area of expertise) and propose a completely novel solution to the problem.
Sharing local knowledge can help form balanced, sound science policy and each of us possess some form of this knowledge. But we need more opportunities to share our perspectives with the scientists and policy makers. “Challenging knowledge hierarchies,” by Dean Nieusma of Rensselaer Polytechnic Institute, examines some dangers of dismissing local knowledge.
But alas, not surprisingly, the conductor did not take this idealistic approach. Indeed I learned about the reasons for the heat-delays from a trusted source: my brother, a safety engineer at Amtrak. He’s a great example of someone not formally trained in the sciences yet capable of understanding and explaining complex science and engineering concepts.  I asked him to explain how the heat affects the trains. Here’s his reply (bear in mind he works for Amtrak so there may be some lobbying efforts threaded in his closing remarks!):
It’s because the wires sag in the hot weather and would rip down if the speeds were not reduced.
The wires (catenary) are tensioned at 5000lbs psi (per square inch). When the weather gets cold the tension could reach as hi as 9000 lbs psi. When the weather get hot (above 95F), and the metal expands, the tension can be as low as 500 lbs psi. This causes the wires to sag. When you have a sagging condition the pantograph (the part on the top of the train that rides along the wire providing the engine with electricity -11,000 volts AC/ 25 hertz) pushes against the sag. If the trains do not reduce their speed, no higher than 85 mph, the pantograph has the potential to pass the ‘sag’. If this happens it will cause the pantograph to become entangled in the trolley wire (the wire that actually touches the pantograph) and could rip down the catenary. You would then be more than 15 minutes late and the union guys would have a lot of wok to do to get everything back in running order.
There is a way to prevent the sagging. It’s called ‘constant tension’. Constant tension is a system of pulleys and weights. The weights keep a constant 5000 lbs of tension on the catenary system thereby eliminating any potential for sagging.
We have constant tension north of New Haven, Ct. to Boston, only because this area was recently electrified. The railroad south (or west in RR terms) was built back in the 1930’s and is deemed too expensive to modify. Europe has constant tension. The reason for that is during WWII we blew most of Europe up and after the war gave them money to rebuild their RR’s, of course with only the best.
Good enough?

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