Things You May Want to Know About Industrial Safety System: an Overview of Industrial Safety System

An overview of industrial safety system

Of the six states that I-75 traverses, the segment in Tennessee is the shortest, at 161.86 miles (260.49km). Between Chattanooga and Knoxville, I-75 follows the route of U.S. Route 11 (US 11), and from Knoxville into Kentucky it follows the route of US 25W. Beginning in Chattanooga, I-75 follows the route of US 41 for the rest of the length to its southern terminus in Miami.

Exit list of industrial safety system

History of industrial safety system

The 25.8 miles (41.5km) section between US 25W/SR 63 in Caryville and US 25W in Jellico was opened to traffic on October 22, 1968. The 0.7 miles (1.1km) segment in Rocky Top, located between US 441 and US 25W, opened on September 1, 1970. The section between SR 60 and SR 308 in Bradley County began construction in 1968, but was stalled shortly thereafter. Construction resumed in 1972, and the segment was opened to traffic on January 23, 1973. The section between US 25W north of Knoxville and SR 61 in Clinton broke ground in segments, beginning in August 1968, and was opened to traffic on August 1, 1972. The approximately 6 miles (9.7km) segment between SR 61 in Clinton and US 441 in Rocky Top was completed in September 1973. The section of the highway between SR 308 near Charleston and SR 30 in Athens opened on December 24, 1973, and was completed the following spring. The last section of I-75 in Tennessee, approximately 32 miles (51km) between SR 30 in Athens and US 321/SR 95 in Lenoir City, was opened to traffic on December 20, 1974, in a ceremony officiated by then-governor Winfield Dunn. The last sections of I-40 and I-81 in Tennessee was opened on this same day.

I-75 originally continued into downtown Knoxville then turned to the north at Malfunction Junction, following what is now signed as I-275. When the western section of I-640 was completed in 1982, I-75 was moved to overlap the auxiliary route to divert through traffic away from downtown in preparation for the 1982 World's Fair. This concurrency is somewhat unusual in that the exit numbers and mile markers follow the auxiliary route I-640 instead of I-75 mileage.

Fog hazardsAn approximately five mile section of I-75 in northern Bradley and southern McMinn Counties, including the bridge over the Hiwassee River is prone to hazards from dense fog in the morning, which can severely obscure the visibility of drivers. This segment is located near several heavy industries including the Resolute Forest Products paper mill, formerly Bowater, which operates settling ponds along the interstate. This segment has been the site of several serious multivehicle accidents, the first of which occurred on March 9, 1974, less than three months after the section opened to traffic, and before it had been declared complete. This accident involved 18 vehicles, and killed three and injured 10. A total of six multivehicle accidents occurred along this stretch in the 1970s. The worst, which took place on November 5, 1978, involved 62 vehicles and injured 46, and took place on the Hiwassee River Bridge. After a multivehicle accident on April 15, 1979 which involved 18 vehicles, killed three, and injured 14, TDOT identified the stretch as prone to fog hazards, and agreed to install warning signs with flashing warning lights, which would activate if fog was detected. After this, no serious fog related accidents occurred for more than 11 years.

On December 11, 1990, a 99 vehicle accident occurred in this same area that resulted in 12 deaths and 56 injuries. This accident was considered unusual, due to the density and sudden appearance of the fog, and initial speculation arose about the possibility of the role of water vapor. Extensive investigations followed, and some meteorological experts believe that the fog may have been caused by an unusual phenomenon known as a temperature inversion. Several lawsuits were filed against Bowater, alleging that they had contributed to the fog with their water vapor emissions. A study conducted by researchers at the University of Tennessee in January 1979 had concluded that Bowater's settling ponds were possible contributors to fog in the area. Several lawsuits were also filed against the state of Tennessee, which claimed that TDOT had failed to install adequate warning systems along this stretch of I-75, a position that Bowater also took. The existing fog warning lights were reportedly not working on this day. After settling with the family members of accident victims and survivors in court, TDOT instituted several safety measures along this stretch of highway, including re-striping the roadway with extra markings to make it more visible and installing a computerized fog detection system, which contains a warning system with flashing lights, electronic signs, variable speed limits, and electronic controlled swing gates which block access to the interstate from six entrance ramps in and near this stretch in the event of dense fog. Between mileposts 31 and 39, the highway is designated as a fog advisory zone. A $5.5 million upgrade was completed to this system in 1993, and in 2006, a $6.6 million upgrade was completed which installed video cameras. Bowater also agreed to limit the use of their settling pond closest to the interstate. The accident was profiled in a 1997 episode of the show Forensic Files.

Geological difficultiesThe entire section of I-75 in Tennessee north of Knoxville has been subject to many geological difficulties, particularly the last 30 miles through the Cumberland Mountains.

In March 2005, the southbound lanes of Interstate 75 were shut down between mile marker 141 to 143 due to a rockslide below the roadway that caused the pavement to partially collapse.

In March 2012, the southbound lanes of the interstate were again closed to traffic between mile markers 141 and 143 in Campbell County, Tennessee due to a slide beneath the roadway.

This was later followed by a second slide in early May 2012 that caused a portion of the southbound lanes to completely erode and forced the detour lanes to be closed.

In February 2016, a rock slide closed I-75 near Caryville, Tennessee.

Other incidentsOn March 28, 1994, a runaway barge that had broken loose from its mooring due to flooding struck the I-75 bridge over the Tennessee River, along with the US 11 bridge and a railroad bridge. The collision broke loose a chunk of concrete from a post, but engineers determined that it caused no major structural damage. I-75 had been closed to traffic on this section in preparation for the collision.

On April 1, 2019, part of the bridge on I-75 southbound over the ramp from I-24 westbound to I-75 northbound at the split in Chattanooga collapsed, injuring one person and blocking traffic for hours. The bridge, built in 1959, is one of the oldest on I-75 in Tennessee, and the interchange is the site of frequent accidents. TDOT's chief engineer said that the collapse was most likely caused by weakening of the bridge's rail that occurred when an illegally oversized load hit the bridge.

ImprovementsThroughout its history I-75 has seen many reconstruction and widening projects in Tennessee.

The first major reconstruction project was a widening of the concurrent segment of I-75 and I-40 from four to six lanes between the interchange near Lenoir City and Downtown Knoxville, which began in the late 1970s. In the latter 1980s, I-75/I-40 was widened from six to eight lanes between the Pellissippi Parkway and Papermill Road, and multiple interchanges along this segment were reconstructed. These segments have since seen more improvements.

I-75 was widened from four to six and eight lanes in Chattanooga between the interchange with I-24 and SR 153 in the late 1980s. Between 1998 and 2010 a series of projects reconstructed and widened I-75 between SR 153 and north of US 11/64 in Ooltewah. The first of these projects, which began in late 1998 and was completed in 2001, rebuilt the interchange with SR 153, changing the approach of two flyover ramps that connect to I-75 northbound from the left to the right side of the road. This project also modified the interchange with SR 320, removing two cloverleaf loop ramps from I-75 southbound, and moving the access to the entrance ramp from I-75 southbound to a point near the interchange with SR 153. The next project, which widened I-75 further between mileposts 6 and 9 and improved the interchange with SR 317, was completed in November 2005. A new interchange was constructed in 2006 to provide access to the Enterprise South Industrial Park, which at that time was in the process of redevelopment. This interchange, which became exit 9, now provides access to the Volkswagen Chattanooga Assembly Plant, and was not opened until 2010. A segment of SR 317 was later routed onto a concurrency of I-75 between exit 11 and this interchange. Exit 9 was designated as the Bredesen-Ramsey Interchange in 2015 in honor of the efforts of then-governor Phil Bredesen and county mayor Claude Ramsey to bring Volkswagen to Chattanooga. The last of these projects, which began on November 8, 2007, widened I-75 from approximately milepost 10 to milepost 13, just north of the interchange of US 11/64, and included reconstruction of this interchange, including the addition of a loop ramp, and improvements on this road. This project was completed on August 12, 2010, four months ahead of schedule.

On May 1, 2008 I-75 northbound traffic was re-routed back along its original path in downtown Knoxville along Interstate 275 as part of SmartFix 40, a major construction project that includes closing a portion of I-40. Traffic was re-routed along I-275 as the ramp from I-640 eastbound/I-75 northbound to I-75 northbound is only one lane which causes traffic delays at peak times.

In December 2018 a contract was awarded to rebuild the interchange with I-24 in Chattanooga. Preliminary work began in May 2019, with completion estimated by June 2021.