United States/Road signs

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Flag of United States Part of United States mapping project.

Sign codes

Main article: MUTCD
Map showing state adoption of the 2009 MUTCD:
     Adopted MUTCD      Adopted MUTCD with state supplement      Adopted state MUTCD

The traffic_sign=* tag is optionally set to an ISO 3166 country code followed by a specific sign code. The source for most sign codes in the U.S. is the Federal Highway Administration's Manual on Uniform Traffic Control Devices (MUTCD). The designs are detailed in a separate document, Standard Highway Signs and Markings (SHSD).

Unlike in other countries, the national standard is not mandatory nationwide. Several states substitute their own state-level MUTCD standards; many other states supplement the MUTCD with state standards. Regardless, in a given state, most sign codes match the national standard. State-specific sign codes represent at most a small fraction of the signs in a given state.

Highway route shields

Highway driving in the US is a way of life and features prominently in film and TV series. The highway system delivers all manner of goods to Americans from food to building materials and from lubricants to pet rocks.

The highway shields for the Interstate system and US Route system are iconic to US drivers. A glimpse of the familiar blue and red Interstate shield provides context to the situation immediately. Will this next scene in the film include a dramatic highway chase? Do the parents face a long drive with their caterwauling children?

The shields are even more useful for navigation. It is their ubiquity and recognizability that returns lost drivers to their intended routes. They allow reasonable assumptions of road quality when changing plans due to traffic, weather alerts or construction.

Wouldn't it be nice if OSM maps of the US could have the familiar highway signs, used appropriately?

Implementations

TopOSM was perhaps the first OpenStreetMap-based map to use U.S.-specific shields. It used the MUTCD-standard Interstate and U.S. route shields and a square marker for state routes. Similarly, MapQuest Open displays state routes as rounded rectangles. Stamen Design's Terrain map additionally features California state highway shields. It uses Skeletron to optimize marker positioning.

In 2010, Richard Weait developed a crude overlay displaying reassurance-style markers for some U.S. state and Canadian provincial routes. At SotM 2011, he discussed future work to reliably mark concurrencies, an area in which commercial maps also fall short.

In 2012, Phil! Gold incorporated these ideas into an experimental rendering that marks each Interstate, U.S., and state highway route relation with cutout-style shields. Unlike other online maps, this map uses state-specific shields and even handles many one-off parkways, such as the Pennsylvania Turnpike. The map is implemented as an overlay atop OpenStreetMap's standard Mapnik stylesheet. See the talk-us thread for details and Launchpad for the source. In 2013, it was added to openstreetmap.us.

There is an open request to implement similar functionality in the Standard map style at osm.org.

Rebusurance is a suite of scalable image assets that can be used for displaying U.S.-style route shields on a map.

Interstate Highway System

The US Interstate Highway System is well-described on Wikipedia. International OSM contributors are encouraged to read the Wikipedia article.

I-shields.png

The Interstate shield two widths and several variations. As always Wikipedia knows all and many specific shield can be seen there.

Perhaps OSM can allow tagging to include these shield in US maps?

US Interstate tagging

Use the talk section of this page to suggest how this should be tagged.

US Highway System

The US Highway system predates the Interstate system. It is ably described at Wikipedia. US numbered highways or "US Routes" may be surface streets or motorways.

US-shields.png

More shields and variants can be found at Wikimedia

California variant

US-shields-ca.png

Bannered variants

Banners route shields include Truck, Alternate, Business, Bypass, City, Spur, and others.

US-shields-banner.png

State highway systems

Main article: United States/Road signs/Generic shields

All states in the US also have a state highway system which consists of hundreds of state-maintained roads that don't fall into the Interstate or U.S. Route systems. State highways can have bannered variants like U.S. highways above. The federal MUTCD suggests using a circular shield with a black background for state highways; however, the states are free to come up with any design they desire. Delaware, Iowa, Kentucky, Mississippi, and New Jersey use the circular highway shield. (Oklahoma did the same until 2006.) Vermont uses the circular shield for segments of state routes that are maintained by the encompassing town. Virginia uses the circular shield for secondary state highways, and West Virginia uses it for county roads. The other states use custom designs. A gallery of the state highway shields in use is available on Wikipedia.

Ideally we would be able to use these shields in maps (Wikipedia usually does this), but as there are 47 different designs doing so is liable to be quite inefficient. Also, some shields are slightly impractical at the small sizes required by maps.

In addition, some states (Tennessee, Texas, Missouri, Montana, Virginia) have a secondary state highway system which uses different shields. Texas actually has several secondary systems, including Farm-To-Market Roads (FM), Ranch-To-Market Roads (RM), Ranch Roads (RR), Park Roads (PR), Beltways, and of course several of these have bannered variants. There's also a unique "NASA Road 1" in Houston which is state maintained. Missouri's secondary system is well-known because it uses one- and two-letter designations (which sometimes leads to eyebrow-raising junctions when letters that spell out words happen to intersect).

Traditionally, road atlases and online maps rely on generic shields to simplify the user experience: for example, a state route always looks like 7 and a county route always looks like 157. However, these generalizations can be counterproductive depending on the use case.

Bike Routes

Main article: Cycle routes#United States

See also