Acceptable East Link Bel Red Noise Levels?

 My February 3rd Gmail included the following announcement: 

Live wire light rail vehicle testing coming up on East Link. 

Full speed ahead! Starting the first week of February 2022, live wire light rail vehicle testing will be rolling out on the East Link light rail tracks. This exciting phase of testing will allow crews to ensure that the new line will be ready for riders. 

Trains will be moving at typical speeds (20 - 35mph) on the tracks between the Bellevue Downtown, Wilburton, and Spring District stations. Nearby neighbors may hear a low hum from the train as it passes. Crews will be conducting this work overnight, between the hours of 9 P.M. and 5 A.M., starting Thursday, February 3rd and ending Sunday, February 6th. 

The announcement raised questions. Will “Full speed ahead” for East Link trains be limited to 20-35 mph? Link trains typically run at 50-55 mph except under UW campus. There they are limiting speeds to avoid exceeding vibration limits with their “Master Implementation Agreement” with UW. However, the slower speeds will increase commute times. What forces Sound Transit to limit East Link speeds in Bel-Red to 20-35 mph? 

The warning “Nearby neighbors may hear a low hum from the train” implies a potential noise problem. Where does Sound Transit consider to be “nearby” and what do they consider to be an acceptable “low hum”? The 9 p.m. to 5 a.m. hours assure most people will be inside. When East Link begins operation those living “nearby” will have trains “passing by” every four to six minutes for twenty hours a day. They may have a different opinion than Sound Transit about the acceptability of a “low hum.” Who gets to decide what's acceptable?

“Nearby neighbors” have reason for concern. Light rail train noise forced Sound Transit to insulate homes some 300 feet from Central Link tracks. Train noise was a major concern along the route into Bellevue from I-90. The result was a Sound Transit June 2011 Supplemental Draft Environmental Impact Statement (SDEIS) concluding: 

 A large number of properties along the route into Bellevue required one of the below options to mitigate light rail noise.  

1) Sound Wall on structure      

2) Sound Wall on structure -- and special trackwork 

3) Sound wall on west side of tracks.  

4) Sound insulation, if required 

In addition, Sound Transit has listed several properties they may purchase because of noise concerns. 

The result was the Bellevue City council required Sound Transit plan to spend millions on noise barriers shielding those living along the route into Bellevue. A later November 6, 2013 blog post opined: 

The noise envelope for the elevated tracks along major sections in the Bel Red area would seem to be a far more serious concern than for at-grade tracks along the route into Bellevue.  Central Link experience has also shown relatively small radius turns along the elevated Bel Red route can be particularly “noisy”. 

Yet they’ve made no attempt to shield those living along East Link from Bellevue to Overlake and eventually to Redmond. Are the trains quieter now or do they intend to reduce noise levels by limiting speeds?  What is their "low hum" requirement?

“Nearby Neighbors” beware!