Mill Avenue Bridges
Encyclopedia
The Mill Avenue Bridges consist of two bridge
s that cross the Salt River
in Tempe, Arizona
at the north end of the shopping district on Mill Avenue. The first bridge opened in August 1931 and the second bridge opened in 1994.
, a former Tempe doctor and the governor at that time. The creation of this bridge replaced the Ash Avenue Bridge which was a dilapidated, one-lane, wagon bridge just to the west. It was demolished in 1991. In the Phoenix
area, it was the sole crossing at the Salt River for some time.
Water flowed down the Salt River until the 1940s, when dam
s were constructed upstream. The water flow almost ceased, creating a dry river bed to support the growing Southwest
. For years, southbound traffic used both lanes of the bridge, while northbound traffic utilized an unbridged crossing in the riverbed.
Despite the Salt's being a dry river, water occasionally flowed. When reservoir levels got too high, the dams were required to release water, causing water to flow once more. Due to monsoon storms heavy rains would fall, and washes and street runoff emptied into the river. At such times the unbridged crossing was closed, and the bridge was opened to north- and southbound traffic, one lane in each direction.
The bridge faced many strong floods that raged through the Salt River Valley
. In 1980 all but two of the bridged crossings on the Salt River were closed for safety reasons (principally erosion of the approaches) due to severe flooding. The Mill Avenue Bridge and one other bridge in Phoenix were the only bridges that remained open. This was because they were structurally sound to stand up to the raging currents. Water hit the bridge at 200000 cuft/s, which far surpassed the expected strength of the bridge. In one 24 hour period during this flood, 92,000 vehicles crossed the bridge.
The Old Mill Avenue Bridge is listed on the Tempe Historic Property Register. It was the 8th property to be added to that list, receiving designation on November 4, 1999.
The New Mill Avenue Bridge (located directly to the east, upstream) opened in 1994 to relieve the original bridge from the increasing traffic. This allowed for two lanes to travel in each direction (North and South), instead of the previous single, two-lane bridge. With the opening of the northbound bridge, the unbridged crossing was permanently closed. With two lanes now running in each direction no matter the weather, monsoon storms and releases from dams no longer lead to traffic obstructions.
In 1999 the dry river bed was transformed into a dammed artificial lake. Tempe Town Lake
was a key success to the revitalization of Downtown Tempe. Formerly just a crossing over the (usually) dry river, these bridges became a centerpiece of the new lake. This prompted a lot of development along the lake. Today, mid-rise offices rise above the southeast portion of the bridges.
Every Fourth of July the CBS 5
July 4 Tempe Town Lake Festival is held at the lake. The fireworks for the celebration are launched from the bridges.
The Mill Avenue Bridges complex also includes two rail bridges slightly downstream from the motor-traffic bridges: a railroad bridge of many decades' standing, and parallel to it a new bridge to accommodate the Phoenix Light Rail
system, which opened in late 2008.
Bridge
A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...
s that cross the Salt River
Salt River (Arizona)
The Salt River is a stream in the U.S. state of Arizona. It is the largest tributary of the Gila River. The river is about long. Its drainage basin is about large. The longest of the Salt River's many tributaries is the Verde River...
in Tempe, Arizona
Tempe, Arizona
Tempe is a city in Maricopa County, Arizona, USA, with the Census Bureau reporting a 2010 population of 161,719. The city is named after the Vale of Tempe in Greece. Tempe is located in the East Valley section of metropolitan Phoenix; it is bordered by Phoenix and Guadalupe on the west, Scottsdale...
at the north end of the shopping district on Mill Avenue. The first bridge opened in August 1931 and the second bridge opened in 1994.
Original Span
The original bridge was built in 1931 but was not dedicated until 1 May 1933. The dedication celebration lasted for two days. Attending the celebration was Benjamin Baker MoeurBenjamin Baker Moeur
Benjamin Baker Moeur was the fourth Governor of Arizona, one of the United States of America.Born in Decherd, Tennessee, Moeur was a doctor before running for public office...
, a former Tempe doctor and the governor at that time. The creation of this bridge replaced the Ash Avenue Bridge which was a dilapidated, one-lane, wagon bridge just to the west. It was demolished in 1991. In the Phoenix
Phoenix, Arizona
Phoenix is the capital, and largest city, of the U.S. state of Arizona, as well as the sixth most populated city in the United States. Phoenix is home to 1,445,632 people according to the official 2010 U.S. Census Bureau data...
area, it was the sole crossing at the Salt River for some time.
Water flowed down the Salt River until the 1940s, when dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
s were constructed upstream. The water flow almost ceased, creating a dry river bed to support the growing Southwest
Southwestern United States
The Southwestern United States is a region defined in different ways by different sources. Broad definitions include nearly a quarter of the United States, including Arizona, California, Colorado, Nevada, New Mexico, Oklahoma, Texas and Utah...
. For years, southbound traffic used both lanes of the bridge, while northbound traffic utilized an unbridged crossing in the riverbed.
Despite the Salt's being a dry river, water occasionally flowed. When reservoir levels got too high, the dams were required to release water, causing water to flow once more. Due to monsoon storms heavy rains would fall, and washes and street runoff emptied into the river. At such times the unbridged crossing was closed, and the bridge was opened to north- and southbound traffic, one lane in each direction.
The bridge faced many strong floods that raged through the Salt River Valley
Salt River Valley
The Salt River Valley defines an extensive valley on the Salt River in central Arizona, which contains the Phoenix Metropolitan Area.Although this geographic term still identifies the area, the name "Valley of the Sun" popularly replaced the usage starting in the early 1930s for purposes of...
. In 1980 all but two of the bridged crossings on the Salt River were closed for safety reasons (principally erosion of the approaches) due to severe flooding. The Mill Avenue Bridge and one other bridge in Phoenix were the only bridges that remained open. This was because they were structurally sound to stand up to the raging currents. Water hit the bridge at 200000 cuft/s, which far surpassed the expected strength of the bridge. In one 24 hour period during this flood, 92,000 vehicles crossed the bridge.
The Old Mill Avenue Bridge is listed on the Tempe Historic Property Register. It was the 8th property to be added to that list, receiving designation on November 4, 1999.
New Span
As traffic congestion increased, the city began preparations for a new bridge crossing parallel to the existing. In the early 1990s construction began on the new crossing. In the spring of 1993, floods returned to the valley again and hampered construction efforts on the new bridge as flood waters tore down scaffolding and form work on the new bridge project. Opening was delayed but eventually the project was completed.The New Mill Avenue Bridge (located directly to the east, upstream) opened in 1994 to relieve the original bridge from the increasing traffic. This allowed for two lanes to travel in each direction (North and South), instead of the previous single, two-lane bridge. With the opening of the northbound bridge, the unbridged crossing was permanently closed. With two lanes now running in each direction no matter the weather, monsoon storms and releases from dams no longer lead to traffic obstructions.
Tempe Town Lake Era
Tempe Town Lake
Tempe Town Lake is a reservoir that occupies a portion of the currently dry riverbed of the Salt River as it passes through the city of Tempe, Arizona just north of Tempe Butte....
was a key success to the revitalization of Downtown Tempe. Formerly just a crossing over the (usually) dry river, these bridges became a centerpiece of the new lake. This prompted a lot of development along the lake. Today, mid-rise offices rise above the southeast portion of the bridges.
Every Fourth of July the CBS 5
KPHO-TV
KPHO-TV, channel 5, is a CBS-affiliate television station located in Phoenix, Arizona, USA. KPHO-TV is owned by the Meredith Corporation, and has its studios located on Black Canyon Highway in the Alhambra Village section of Phoenix, with its transmitter located on South Mountain in Phoenix...
July 4 Tempe Town Lake Festival is held at the lake. The fireworks for the celebration are launched from the bridges.
The Mill Avenue Bridges complex also includes two rail bridges slightly downstream from the motor-traffic bridges: a railroad bridge of many decades' standing, and parallel to it a new bridge to accommodate the Phoenix Light Rail
METRO Light Rail (Phoenix)
Metro Light Rail is a 32 km light rail line operating in the U.S. state of Arizona. Part of the Valley Metro public transit system, it serves the cities of Phoenix, Tempe, and Mesa. Construction began in March 2005; operation started December 27, 2008...
system, which opened in late 2008.