Regarding the article: “Agencies seek fixes to mudslides, train disruptions,” I write to bring up a point that, from what I have read, seems to have been overlooked by some with regard to the mudslides we have been observing recently. The cliffs lining much of the rail line between Seattle and Everett seem to be thixotropic in nature. Materials exhibiting this characteristic loose viscosity when subject to shear stresses induced by, among other things, vibration.
We have all felt the vibrations created by the passage of trains while waiting for trains to pass, and these vibrations certainly have a deleterious effect on these cliffs, but they are small compared to the vibrations that would be created by the passage of heavily laden coal cars weighing up to 121 tons. Add to that the fact that it is projected that coal trains may contain as many as 115 of these monsters. At any train speed, the vibrations would continue for long periods of time. The combination of these factors:
Heavily loaded rail cars.
Over-extended time periods.
Nearby cliffs that exhibit thixotropic characteristics concern me, and, I think, should concern all of us.
This issue must certainly be addressed before the proposed coal trains are permitted along this stretch of our shoreline.
James D. Chalupnik