One good reason to leave plenty of following distance behind trucks is
that they tend to throw up detritus from the road, including small stones
which can sometimes fly a good distance in the air before landing --
enough hang time to strike the windshield of a car behind. More room
allows more time for them to settle back onto the road. But all the
distance in the world doesn't help when a truck is going the *other way*
on a two-lane road and carries its own on-board supply of rocks to drop,
which also has the unfortunate side-effect that they're moving faster
opposite our own direction of travel as they bounce high into the air.
I was just heading out for a brief roadtrip to the Cape, and part of my route to the highway goes past a gravel supplier. Their dump trucks are always pounding in and out of the area and they're usually pretty good about load securement and using the load covers, but they can't be totally certain what happens over the occasional big bump. As I approached the highway one of their trucks went by the other way and probably slammed over one of the still-unpatched holes near the bridge expansion joint, because the typical boom I could hear from that was quickly followed by a loud *KAK!* and I realized that something new had just appeared slightly above my sightline and it wasn't a squashed insect. |
Here's what it looked like from the inside. I didn't immediately abort the
trip, but continued onto the highway and watched the crack a bit -- it wasn't
expanding any farther as I approached the next exit from which I could have
gone to an auto-parts store, so I continued my run to the Cape and figured
I'd have some time to try and fix it there.
Somewhere in Falmouth I found an auto-parts place and got one of the fix-it kits from Permatex, and retired to a convenient and mostly tree-shaded slot in a parking lot at a Chinese restaurant to attack the problem. |
This got me curious and later I called the tech support at Permatex to ask
what this "patch" really is, as its deceptive yellow color made me wonder
if it's also some kind of light filter and/or special plastic formulation
to interact with the resin in some way. The answer was that no, it's just
a type of plastic that the resin doesn't stick to very well and allows
easy removal later, but keeps air out of the damaged area as the resin
is designed to cure *anaerobically* as well as under ultraviolet light.
It's also flat and smooth and squashes any remaining resin out to a flat
surface that interferes the least with the desired optical characteristics.
This is a bit of a change from what I remembered from the previous time
I did this, where the sealant had been common cyanoacrylate aka Super Glue.
But the Permatex guy said that had fallen out of favor as cyanoacrylate has
a different expansion coefficient from glass and tends to fare less well
over the long term in such fixes. Well, my old fix hadn't had a problem
but that was a smaller crack than this so hopefully I didn't bugger this
up too badly and it will hold well. The cracks are largely invisible
now, so they probably got sealed correctly.
It seems that having one of these kits onboard is probably a good idea for road trips, where a bouncing rock could come along almost anywhere and it might not be at a convenient place or time to go find a local supplier before the damage starts spreading. So, one more thing for the load list. |