Sonny'Side

Post Three: Interstate Highway System

One of the things I think people today take for granted is the Dwight D. Eisenhower National System of Interstate and Defense Highways.  The interstate highway has become more than just a way to move military equipment during times of conflict.  Back in 1919 a group of 294 members of the US Army headed west from Washington, DC in the first military caravan.  Sixty-two days later at an average speed of five miles per hour, they reached Union Square in San Francisco after dealing with poor roads and a number of travel difficulties.  One of the members of that caravan was Army Captain Dwight D. Eisenhower.  During his service in WWII he noticed how durable the Autobahn was in Germany and that a single bomb would only temporarily disrupt transportation on that system of roads.  So when he later became president he pushed for a system of interstate highways and on June 29, 1956 Congress approved a project called the Federal Aid Highway Act (FAHA) and the interstate system as we know it today was started.  What most people probably don’t know is there are a number of guidelines that had to be followed as this system of roads was built.  Listed below are a few of those Interstate Standards. (http://www.interstate-guide.com/interstate.html):

• Access must be controlled, with points of entry limited to interchanges with grade separation. (There are several exceptions to this rule.) Interchanges should be spaced one mile apart in urban areas and three miles apart in rural areas.
• All overpasses must have a 16.5-foot vertical clearance above the freeway, although 14-foot overpasses may be permissible within urban areas. This particular specification was created to allow for military apparatus (such as the huge atomic cannon) to pass cleanly under an overpass. Although military equipment of this size is not commonly transported on the Interstate Highway System (and the atomic cannon is no longer in use), the standard remains. If an overpass cannot be upgraded to accommodate 16.5 feet, then there must be exit and re-entry ramps that allow high profile vehicles to leave the freeway and rejoin the freeway on the other side of the overpass. Truss bridges and overhead signs must meet or exceed 17 feet. Standards may be reduced somewhat for tunnels or other long underpasses.
• Design speed should generally be 70 miles per hour, with 60 miles per hour sections allowed in hilly terrain and 50 miles per hour sections allowed in urban areas or within mountainous regions.
• Maximum grade is six percent, with certain exceptions allowed in mountainous regions.
• Interstates are generally open to all traffic, unless a specific waiver exempting certain vehicles is granted.
• At-grade railroad crossings are not permitted on the Interstate Highway System (standard since 1966).

Numbering Themes

• Directions
• Even Numbers travel east-west (I-4, I-8, I-10, I-12, etc.)
• Odd Numbers travel north-south (I-5, I-15, I-17, I-19, etc.)
• Significance
• Routes ending in "0" are major east-west routes (I-10, I-20, I-40, I-70, I-80, I-90)
• Routes ending in "5" are major north-south routes (I-5, I-15, I-25, I-35, I-55, I-65, I-75, I-85, I-95)

•  Loop routes and through routes that generally connect to an Interstate highway at either end have an even first digit.

• Spur routes and city routes that may or may not connect to an Interstate highway at one end have an odd first digit:

Cool Facts About the Interstate System

• Total Distance - 42,794 mi (68,870 km)
• Longest Route - I-90; Seattle, WA, to Boston, MA; 3,085.27 mi (4,965km)
• Shortest Route - I-97; Annapolis, MD, to Baltimore, MD; 17.57 mi (28.27 km)
• Longest East-west Route - I-90; Seattle to Boston; 3,085.27 mi (4,965 km)
• Longest North-south Route - I-95; Miami, FL, to Houlton, ME; 1892.76 mi (3,046 km)
• Oldest Segment - The oldest segment predates the interstate system. Grand Central Parkway in Queens, NY, opened in 1936 and was later melded into the interstate highway system as I-278.
• The Interstate Highway shield was designed by Richard Oliver of Texas as a black and white shield; the red, white, and blue version was approved by the American Association of State Highway Officials (AASHO) in 1957. It is trademarked.
• Five state capitals are not served by the Interstate Highway System as of 2006: Juneau, Alaska; Dover, Delaware; Jefferson City, Missouri; Carson City, Nevada; and Pierre, South Dakota. The completion of Interstate 580 in 2009 in Nevada will connect Carson City to the system.
• It is not true that one mile of every five miles of Interstate highway must be straight enough to allow planes to land on it. This is an urban legend.

Source: U.S. DOT, Federal Highway Administration

One of the reasons for a post on this topic is because of how and when I use the interstate. Because of where I live I can generally go about my daily routine without getting on an interstate road. However, there are situations that call for using I-26 or I-85 when I want to avoid stop lights and of course those times when we travel and the interstate is the quickest, if not always the shortest, route.  It is easy to forget that those cars on the road with us are also using it for different reasons.  Sometimes they are travelers like we are or they may be just going from one exit to the next just to avoid that busy intersection.  Their destination and duration on the road often contributes to the level of attention they are displaying.  The one request I have for all of you who use the interstate is to drive in the right-hand lane except when passing.  If you are in the left lane, then PASS even if that means speeding up. It is the driver that cruises in the left lane that contributes most to the congestion that causes me and other drivers heartburn.  Be considerate of other drivers and stay safe when driving on any road.  I hope you have enjoyed this little post about our interstate system. Maybe you have learned something or at least will investigate further if you are interested.