Conversion from metric to English units delays freeway interchange

[Drum_God]

Several years ago, the Texas Department of Transportation (TxDOT) built an interchange at the intersection of SH71 and I-35/US290 in South Austin. In typical fashion for Austin, the entire interchange was planned, but only a portion was built. (Interchanges all over Austin have only part of the ramps built. This way, you get years of construction, a new interchange, but still the same old traffic jam. Totally cool. :rolleyes:) Anyway, now TxDOT may have come up with some funding to build the remaining parts of the interchange. According to this article in the Austin American-Statesman, however, the project may be delayed while the plans are revised.

Says TxDOT:

Construction on the four remaining Ben White/I-35 bridges could begin in a little over a year, Daigh said Tuesday. The department has to amend a federal environmental document approved years ago. And, in an oddity, Daigh said that the plans for the bridges were done when TxDOT used metric units. They’ll have to be redone in traditional English units.

My GQ: Why do the plans have to be changed at all? When TxDOT lets out the bids, can’t they just tell the contractors “Hey, this is in metric.”? Obviously, everyone on the project has to agree on the units to use lest bridges fail to meet in the middle (witness NASA’s mission to Mars that ended in disaster because of unit confusion). However, as long as everyone is on the same page, why does it matter what the units are? Build the thing using cubits. Who cares?

So what’s the big deal? Just build the thing already!!

(In a truly inspired example of half-assed highway building, check out my favorite example of the bridge to nowhere. Those columns have been there for nearly thirty years. They are supposed to hold a four lane overpass comprising northbound US183. The southbound bridge was built, but you’ll notice that, while it can hold four lanes, it only is striped for one lane. That’s because, at the southern end of the bridge, is an abutment for the Montopolis Drive underpass. So, it’s a bridge into a wall. Brilliant.)

[The_Flying_Dutchman]

Let me get this straight. Texas had construction plans done in metric before and now they are going back to “english” units?

Isn’t that ass backwards?

Is Texas concerned about the terrorists reading their construction and building plans?

Even England has their construction plans drawn in metric.

[Mycroft_H]

The Federal Highway Administration, in the late 1990s, was making one more push towards metrication.* If the bridge plans were developed during this time and subsequently shelved, that would explain the done-in-metric-going-back-to-English situation.

As to the OP, I can see the powers that be being afraid that too many contractors would complain about trying to access metric labeled components and working with metric units. Not that I agree with it, but I can see the argument being used. It would also probably add to the cost of the project bidding in metric as the construction companies would probably need to convert anyway to order materials. Plus, you run the risk that if something ever went wrong (I’m in Minnesota, land of the collapsed 35W bridge) it would be blamed on conversion difficulties. It’s a problem no one would want to take on.

Redesign should not have to start from scratch, but I would say the new team would have to run design computations again from the beginning instead of applying “OK, we multiply this number by 3.281.” This would be done to make sure that all the numbers mesh properly and that, as you reference in your OP, the bridge does not wind up slamming into the surface of Mars. (Highly improbable, but if that sort of thing can happen to missiles and whales…) Plus a fresh look can be used to apply design techniques learned in the past few years. If this was designed during the Federal metric push, the plans have been sitting around for a 8 or 9 years.

If I may be permitted time for a personal anecdote – In 1997 I started design on a small road project for a Twin Cities area county. I got special permission to design it in English units as that is what all the surveying and preliminary design used and Mn/DOT agreed that it would be costly to convert everything. Anyway, this was going to be the last Federally funded project in Minnesota allowed to use English units. The project got held up for various reasons that added to my hair loss rate and by the time it was constructed, metric plans had been abandoned and the contractors used the English units they were used to. In the ensuing years I did design a few metric projects and love the system. But one should never underestimate the general American public’s hatred of the metric system.

*”One more” meaning that there had been a lame attempt during the 1970s(?) and possible one more after that. After much complaining by most of the transportation design and materials supply industry ([wine]But the metric system is just tooooo confusing[/wine] :rolleyes: ), the whole effort was dropped again around 2001. Dates are all approximate based on a crappy memory.

[Drum_God]

@Mycroft_H

The Federal Highway Administration, in the late 1990s, was making one more push towards metrication.* If the bridge plans were developed during this time and subsequently shelved, that would explain the done-in-metric-going-back-to-English situation.

As to the OP, I can see the powers that be being afraid that too many contractors would complain about trying to access metric labeled components and working with metric units. Not that I agree with it, but I can see the argument being used. It would also probably add to the cost of the project bidding in metric as the construction companies would probably need to convert anyway to order materials. Plus, you run the risk that if something ever went wrong (I’m in Minnesota, land of the collapsed 35W bridge) it would be blamed on conversion difficulties. It’s a problem no one would want to take on.

The interchange was developed during the 1990’s, so the FHA explanation seems likely. I like your comment about not being able to access metric labeled components. There are several Home Depots and Lowe’s stores near this location. If they need a metric wrench, they could probably find one nearby. I suppose liability in conversion difficulties could be an issue. Still, aren’t these sorts of people really, really good at math?

[Tapioca_Dextrin]

@Drum_God

(In a truly inspired example of half-assed highway building, check out my favorite example of the bridge to nowhere.

I drove over that today (not into the wall though).

[Drum_God]

@Tapioca_Dextrin

I drove over that today (not into the wall though).

You might be heading out my direction, then.

[jasonh300]

@Drum_God

(In a truly inspired example of half-assed highway building, check out my favorite example of the bridge to nowhere. Those columns have been there for nearly thirty years. They are supposed to hold a four lane overpass comprising northbound US183. The southbound bridge was built, but you’ll notice that, while it can hold four lanes, it only is striped for one lane. That’s because, at the southern end of the bridge, is an abutment for the Montopolis Drive underpass. So, it’s a bridge into a wall. Brilliant.)

What I don’t get is the westbound traffic on Ed Bluestein Blvd. splits before turning southbound, runs across the two bridges, and then merges back together.

I assume that the bridge(s) in the center were ultimately supposed to replace the outer bridges.

[Drum_God]

@jasonh300

What I don’t get is the westbound traffic on Ed Bluestein Blvd. splits before turning southbound, runs across the two bridges, and then merges back together.

I assume that the bridge(s) in the center were ultimately supposed to replace the outer bridges.

What is supposed to happen is that only traffic that wants westbound Montopolis Drive would exit there and use the older, smaller bridge. The old bridge is also used to gather the traffic from downtown (Airport Blvd., 1st and 7th Streets) and send it onto southbound US183. The original bridge is the western-most bridge with the girders. It used to have one lane in each direction. Later, the existing northbound bridge was added. In the 1980’s, the wide southbound bridge was added, along with the empty bridge pilings. Construction stopped at this point. (The Bolm interchange northeast of the linked map was completed several years ago. It too is constructed for more lanes of traffic than it actually carries.)

I think the problem is that the new highway alignment did not allow for Montopolis area residents to access US183. This was politically not a good idea. Of course, the Montopolis interchange could be redesigned, too, but that would take still more money. Better to ignore the whole thing. :rolleyes:

[Mycroft_H]

@Drum_God

Still, aren’t these sorts of people really, really good at math?

Yeah, but just because you’re good at math doesn’t mean you still can’t be a chicken. Or to look at it another way, if you’re smart enough to handle the math, you’re smart enough to be afraid of lawyers, lawsuits and liabilities. In an ideal world it should not be that way, but we do not live in an ideal world.

[Tapioca_Dextrin]

@Drum_God

You might be heading out my direction, then.

If your direction is on the far side of Istanbul, then yes :eek: