# Urban Legend?-Freeway Bridge Height **URL:** \ **Category:** Factual Questions\ **Created:** [January 6, 2005, 11:10pm UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473 "2005-01-06T23:10:17Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![Diceman](https://avatars.discourse-cdn.com/v4/letter/d/22d042/32.png) [@Diceman](https://boards.straightdope.com/u/Diceman)\ **Post date:** [January 7, 2005, 5:23pm UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/21 "2005-01-07T17:23:58Z")
> [@THespos](#): > > I had always heard that Robert Moses built the parkways such that the overpasses between NYC and Jones Beach couldn’t accommodate the height of the busses, and that Moses was a racist who didn’t want blacks coming to the beach. Never really found a reputable cite, though. [This article](http://www.qgazette.com/News/1999/0630/Feature_Story/) refutes the old story. > > A lot of Long Islanders accept this story as fact, but I’m not so sure. I think this is the story. I seem to remember it including some mention of beaches. ---
**Author:** ![TBone2](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TBone2](https://boards.straightdope.com/u/TBone2)\ **Post date:** [January 8, 2005, 1:43am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/22 "2005-01-08T01:43:49Z")
As I understand it, the original Interstate Highway System was very much designed with specifications geared toward the transport of military vehicles. These specs included bridge heights, among others. While it’s true that Eisenhower witnessed first-hand and admired the advantages offered by Hitler’s Autobahn, it is likely that the inclusion of military specifications in the U.S. version was necessary to circumvent the simple fact that the U.S. Constitution in no way authorizes the federal government to build any sort of highway. That document _does_, however, charge the feds with providing for the “common defense.” Thus, if a proposal (such as an interstate road system) can be shown to benefit the “common defense,” Congress can legally – sorta – spend the money. FDR ran into this problem – the U.S. Constitution – constantly as his flurry of “alphabet soup” programs were systematically dismantled by the Supreme Court. One notable exception was the Flood Control Act of 1933, extended and expanded in 1938(?), which is still around. Thanks to this piece of legislation, the federal government has been in the business of building and operating freshwater lakes for over seventy years. Of course, the Constitution doesn’t say a word about lakes or flood control either, but each of the hundreds of projects in place today under this law was authorized (justified) at least in some tiny part as a benefit to the common defense; the U.S. Army’s Corps of Engineers oversees all construction and operations. ---
**Author:** ![BrotherCadfael](https://avatars.discourse-cdn.com/v4/letter/b/977dab/32.png) [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)\ **Post date:** [January 8, 2005, 2:17am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/23 "2005-01-08T02:17:22Z")
> [@TBone2](#): > > One notable exception was the Flood Control Act of 1933, extended and expanded in 1938(?), which is still around. Thanks to this piece of legislation, the federal government has been in the business of building and operating freshwater lakes for over seventy years. Of course, the Constitution doesn’t say a word about lakes or flood control either, but each of the hundreds of projects in place today under this law was authorized (justified) at least in some tiny part as a benefit to the common defense; the U.S. Army’s Corps of Engineers oversees all construction and operations. The Constitution gives the federal government control of all “navigatable waterways” within the United States. Courts have broadened the definition of “navigatable” to reach almost to the wet spot in the middle of your driveway. I think it is supposed to be any waterway down to three feet across… and includes seasonal wetlands that are “navagatable” only a few months of the year. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [January 8, 2005, 2:25am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/24 "2005-01-08T02:25:40Z")
NPR did a piece on the guy who originally designed the interstate highway system, and while they didn’t label him a racist, they did state that the highway system was designed to favor wealthier (and thus more likely white) areas over poorer ones. They also interviewed the author of a book who claimed to have witnessed the military using the highways in some place like the Dakotas or Montana as runways. I don’t remember if he repeated the UL that the capability for this was required in highway design, or if he was stating that the military just thought of it after the fact. ---
**Author:** ![jeffh3000](https://avatars.discourse-cdn.com/v4/letter/j/34f0e0/32.png) [@jeffh3000](https://boards.straightdope.com/u/jeffh3000)\ **Post date:** [January 8, 2005, 8:33am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/25 "2005-01-08T08:33:25Z")
> [@TBone2](#): > > As I understand it, the original Interstate Highway System was very much designed with specifications geared toward the transport of military vehicles. These specs included bridge heights, among others. Going back to the orginal urban legend that started this thread. The feedback and comment indicate to me that, at this point it looks like there is some level in truth to this urban legend. It looks like there obviously is military feedback at times regarding interstate road specs, but it still seems it may be a bit of a stretch to say that military vehicles carrying missles was a primary concern in this determination. Unless someone has some information regarding specific bridge height requests from the military, for the transport of missles via roadways? Looks like we are getting some good info here. Thanks guys. ---
**Author:** ![jester21](https://avatars.discourse-cdn.com/v4/letter/j/ed655f/32.png) [@jester21](https://boards.straightdope.com/u/jester21)\ **Post date:** [January 8, 2005, 9:23am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/26 "2005-01-08T09:23:37Z")
> [@BobLibDem](#): > > The 4.9 m figure is correct as per the AASHTO Green Book. 4.9 m clearance over the entire traveled way is required over freeways, except that in highly developed urban areas 4.3 m may be used if there is an alternate freeway facility with a minimum of 4.9 m clearance. Also, sign trusses and overpasses have a clearance requirement of 5.1 m. And an allowance of 150 mm is recommended to all clearances to accomodate future resurfacing. > > I’ve been told that in the event that the military was to use the freeways to move equipment and if a bridge prevented such passage, that they are quite able to clear the bridge quickly if need be. That gives me an idea for a funny movie scene: General: Well, any ideas how we get these trucks past the low bridge? 2nd LT: Sir! I’ve composed this 40 page report on how we can bypass the bridge using alternate routes and reloading the equipment onto other vehicles for spans that can not be traversed by the larger trucks. It will only add 4 days to our current ETA. General: I see. Sergeant, any ideas? Sergeant: Yeah. Blow up the damn bridge! ---
**Author:** ![Quartz](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/quartz/32/267_2.png) [@Quartz](https://boards.straightdope.com/u/Quartz)\ **Post date:** [January 8, 2005, 10:40am UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/27 "2005-01-08T10:40:58Z")
> [@GorillaMan](#): > > Any cites? I’d like to see these mile-long straight stretches in that rather imposing terrain. I’ve seen pictures of Saabs dispersed on exercises. ---
**Author:** ![Meurglys](https://avatars.discourse-cdn.com/v4/letter/m/258eb7/32.png) [@Meurglys](https://boards.straightdope.com/u/Meurglys)\ **Post date:** [January 8, 2005, 1:51pm UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/28 "2005-01-08T13:51:46Z")
> [@Quartz](#): > > I’ve seen pictures of Saabs dispersed on exercises. > [@](#): > > Originally Posted by GorillaMan - Any cites? I’d like to see these mile-long straight stretches in that rather imposing terrain. I remember reading an article in _Look & Learn_ (informative children’s weekly magazine) in the late 60s about this. The (Swedish) road in the artist’s impression was in a wooded area and a STOL aircraft of some sort was sitting on a small apron area beside the road; I think there were some small buildings (fuel store, maybe?) there as well. The ‘runway’ section of road was a bit wider and stronger than the usual construction and was, I think, 200 or 300 meters long. ---
**Author:** ![TBone2](https://avatars.discourse-cdn.com/v4/letter/t/6a8cbe/32.png) [@TBone2](https://boards.straightdope.com/u/TBone2)\ **Post date:** [January 8, 2005, 3:08pm UTC](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473/29 "2005-01-08T15:08:25Z")
OK, maybe I wasn’t as clear as I could have been… I didn’t say, and didn’t mean to say, that military requirements were the “primary concern” in interstate highway design. My point was that such requirements had to be included to enable Congress to circumvent the Constitution. Ike wanted it. Congress wanted it. The voters wanted it. Heck, I even wanted it, and I distinctly recall messing my diaper in support of it! But the Constitution stood in the way, as it does with a great many things the federal government wants to do. That document was (very purposely!) framed in such a way that, if a specific activity isn’t clearly placed with the federal government, it is automatically relagated to the individual states. The building of highways ain’t in there, so it goes by default to the states. (Take this a bit further and imagine the U.S. criss-crossed with state-built toll roads… Hmmmm…) Ike and Congress put their heads together and came up with a way the feds COULD get in the road-building biz. (“We’ll say it’s a military thing, throw in some army specs, and everything will be cool.”) So what was the “primary concern?” My guess is money, which is the equivalent of power in our political system. The FHWA (or whatever it’s called nowadays) carries a big money stick, and uses it to “encourage” the individual states to lower speed limits, pass mandatory seatbelt laws, reduce DUI BAC levels, and so on. And that’s as far as I’ll venture into politics… [Previous page](https://boards.straightdope.com/t/urban-legend-freeway-bridge-height/283473.md?page=1)