State Route 840 Now Designated as Interstate 840 NASHVILLE – The Tennessee Department of Transportation has received approval from the Federal Highway Administration to designate State Route 840 as Interstate 840. The change was requested to encourage more economic growth along the corridor and more traffic diversion around Middle Tennessee’s urban core. The primary purpose of SR 840 when it was initiated in 1986 was to promote economic development by improving access to the many communities located along the route. Since then, more than 20 major industrial sites have opened directly adjacent to SR 840. Having an interstate designation could encourage more industries to consider locating in Middle Tennessee, which increases employment opportunities for the state. Interstates also provide a level of expectation and confidence for drivers. Motorists can maintain a higher speed and avoid congestion that may be found on state routes. TDOT anticipates the interstate designation will encourage passenger and freight traffic moving through the state to take the route, which will help to reduce congestion in Nashville and surrounding areas. TDOT will begin installing I-840 signage next week, and expects the work to be complete late this year. The cost to replace signs on state routes and interstates is $230,000. The 840 corridor was completed in 2012, providing access to Interstate 40 west and east of Nashville, along with connections to Interstates 24 and 65. It travels through Dickson, Hickman, Williamson, and Wilson Counties.