Wednesday, April 08, 2009

Getting On and Off in Texas

Heading out for some time out, I once again have to drive to the nearest major airport and do a handover with a replacement pilot. The airplane is in for scheduled maintenance and will be at least a couple of days, so this time I'm dropping off the car and flying out this afternoon, and then my replacement will pick up the car and drive back to the worksite when he arrives.

The USA has great highways. They are usually well-paved, with yellow lines in the middle, clear lane markings and white lines along the edge so you don't drive off the road. They usually have lots of bright reflective cateyes while Canada typically has only the glue marks left behind after the snowplough scraped the cateyes off the pavement. Some amazing engineering goes into the urban highway ramps. Some places they are stacked five or six layers deep. I'm sure there are dozens of advanced textbooks and hundreds of engineering theses on how to curve and bank an exit ramp, how long to make an exit or entrance lane, and where to put signs such that drivers can interpret them in time to make lane changes.

There are national, state and possibly also county highways and they have different formats. So one sign might direct you to 131 North, 23 South and East Loop. And the signs can be on the same pole so you see "East Loop 131 North 23 South." And then you're looking for 23 North and you see "North 23" and you go for it, realizing as you're committed to the ramp that that's 131 North and 23 South. So you're going the wrong way. Fortunately it's usually simple to exit, cross under the highway and get back on going in the proper direction. Okay, further evidence that Aviatrix can't drive. What else is new.

Texas on ramps: Some of them live up to that state of the art engineering picture. And some of them appear to have been built by the Dukes of Hazzard as a one-off. I guess the highway goes through all kinds of towns, and all of them want access. I have literally missed highway entrances to I-20 because I thought the ramp concerned was one of those dirt roads that cops use to do U-turns rather than a legitimate highway entrance. After a time I came to realize that while the interstate has a dependable consistency from Shreveport to Fort Worth and on to California, the entrance ramps aren't necessarily paved. It lends the interstate an exotic flavour, like The Road in Zelazny's Roadmarks.

Oh, and an airplane cartoon, just so I don't have to put the non-aviation tag on this.

13 comments:

Peste said...

Roadmarks, actually.

Fastest round trip from reference taken as recomendation to, let's say, purchase, to love at first sight yet, in 17 years. Thanks!

Free Flying Mom... said...
This comment has been removed by the author.
The Flying Pinto said...

The highways are great and well paved and laid out down here in TX...but if you head up to the North East this is not the case....we have huge pot holes and old confusing roads. In fact the highway from Boston to Cape Cod is only 2 lanes! And, don't even get me started on driving any where near Boston Logan Airport or Newark Airport! Talk about nightmare!

Oh, and you made me laugh when you said you can't drive....none of the pilots I know have any sense of direction on the ground;-)

Sarah said...

Excellent! A Zelazny I've never heard of and which is out of print. I'll start looking. It will be like a gift out of the past.

Angus said...

Gotta love dirt ramps on the interstate! Would that be chapter one or chapter two? ;-)

Anonymous said...

Hmm... let's see... you're Canadian, with a temporary flight assignment out of Texas, and I'm from the states, temporarily flying out of Hamilton. Trust me, you've got the best weather.

Aviatrix said...

Thanks for the title correction. Fixed.

Astroprof said...

Unless under construction, the interstate on-ramps in Texas should all be paved. Granted, the paving sometimes is in disrepair, narrow, unlit, or dirty from debris washed onto it ...

They are also sometimes placed in the oddest locations. That's why in many small towns the locals sort of make their own unofficial on-ramps, just cutting across the grass. Though commonly used by the locals, you can still get a ticket using one if a state trouper sees you doing so.

Dave Earl said...

One thing Texas does great is that many of the frontage roads have a loop under the freeway to reverse course. I generally don't get trapped going the wrong way for long. :-)

One thing they do poorly (along with Florida) is consistent names on signs - you might be looking for Hwy 8, The SH toll road or something else and it might change as you progress...

zb said...

Maybe we have a civil engineer around here to clarify, but anyway, this is what I've heard once: There's a mathematic concept of how to shape a curve on the road in order to have the drivers make smooth movements on the steering wheel. It works something like this:
When entering the curve, you start rotating the steering wheel at what might be close to a constant rotational speed until you reach the middle of the curve, then you rotate the steering wheel back to the middle position, again at a constant (or harmonic) rotational speed.
This makes it safer and more convenient for drivers and requires the radius of the curve to be quite big at its start, then gradually become smaller until you reach its maximum curvature, and become bigger again until the road completely straightens out. (In contrast to having a straight road, a curve with a fixed radius, and a straight road again.)
There's a formula and there's a name for this type of curve as well, but I don't remember them.
If I remember right, there are countries that try to build their roads according to these rules, and an educated observer will be able to tell.

dpierce said...

ZB -- A racer calls it a decreasing radius turn, civil engineers call them spiral curves or transition curves. The idea is to avoid introducing the vehicle to the controlling radius all at once, so they can exit the highway at a relatively high speed, and gradually slow down in the turn (or enjoy a good tire squeal -- whatever floats your boat) until it opens up again. Yes, if it's done well, you'll have a very smooth steering movement.

They are a source of debate. Some people (mostly who aren't used to them, I'd guess) consider them dangerous because they're not expecting the decrease, and, misjudging the turn, fly off the road.

On the other hand, you have tight constant radius turns as I've seen in some parts of the world that essentially require you to get down to about 40mph while still on the highway in order to enter the turn. (Which could also be considered dangerous.)

Johnson said...

Ah, glorious I-20. I've spent much of my life on that stretch of road from Tyler to DFW, but I've never looked at it from such a perspective... there is a steep learning curve if you haven't grown up with it. And I've always been in awe of all those overpasses in the Dallas area... I have some friends who are civil engineers and I've seen those textbooks you mentioned- they're ridiculously huge and complicated. I'll stick to my instrument handbooks, thank you very much.

Well, keep on trying to figure out these Texas roads! I also have to say that as a native of east Texas, we most definitely have the best roads in any part of the state!

Anoynmous said...

Roadmarks is responsible for my giggling to myself each time I encounter the word "copious".