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Transportation Management Office - Emergency Reference Markers


Smartway logoWhat is the purpose of the blue signs placed along the medians and ramps of the Interstate highways in Chattanooga, Knoxville, Memphis and Nashville? In emergencies, those signs serve the same purpose as the "street addresses" on other streets and highways. TDOT is testing the use of these signs to improve emergency response to Interstate crashes and other incidents.

When a problem occurs on an Interstate highway, passing motorists call "911" or "*THP," and those calls are important to quick response. However, the callers are frequently unclear about their exact location, route, and direction of travel. Without that information, the emergency responders—law enforcement officers, fire and emergency medical services, the HELP operators, and others—have trouble knowing the location, exit/entrance ramp to use or even which of the available units should be dispatched. 

Photo of Median Reference Marker and Ramp Reference MarkerMedian Reference Markers
TDOT has installed two signs, one facing in each direction, along 228 miles of Interstate highways in the four metropolitan areas. Each sign gives four pieces of information:

  1. Direction of travel
  2. Interstate route the motorist is traveling
  3. Milepost
  4. Tenth of a mile past the indicated mile post.

If you report an emergency, look ahead in your direction of travel for a blue sign and then report all of the information. For instance, "The crash is Eastbound on Interstate 440, near mile 2.2 (2 and 2/10ths)." 

(Please note that the signs are placed in both directions of travel, often back to back on the same post. If you look behind you at a sign in the opposite direction of travel, the sign will indicate that direction and, therefore, the opposite side of the Interstate.) 

Ramp Reference Markers
You may also have noticed signs on ramps from one Interstate to another Interstate. The ramp sign shown above tells you (and emergency responders) that you are on the ramp from Interstate 24 westbound going to Interstate 65 southbound.  The small square at the bottom indicates that this is the second sign on the ramp.  All of the Interstate-to-Interstate ramps have three or four of these emergency reference signs equally spaced along the full length of the ramp.