====== Transcontinental L-3I System ======

During the early 1960s, AT&T built a high-capacity transcontinental cable hardened against nuclear attack. The L-3I transcontinental cable served both to add reliable capacity to AT&T's commercial network, and to provide a hardened backbone for the rapidly growing AUTOVON military telephone system.

The transcontinental L-3I cable is a multi-core coaxial cable using the [[carriers/coaxial|L-3I or L-3 Improved carrier]]---a multiplexing technology that could transmit up to 9,300 simultaneous phone calls. The L-carrier technology required repeaters every four miles, located in small underground vaults below distinctive metal huts, and large underground "main stations" at least every 200 miles. The main stations were staffed by maintenance crews 24/7, and were hardened and supplied to ride out a nuclear war.

<olmap id="bigMap" width="100%" height="500px" lat="38.5" lon="-104" zoom="9" controls="1" baselyr="OpenStreetMap" kmlfile="routes:transcontinental_l-3i:map.kml">
</olmap>
(you can {{ :routes:transcontinental_l-3i:map.kml |download this KML file}})

===== L-3I Facilities =====

{{topic>l3i}}