Sundial Bridge at Turtle Bay
Encyclopedia
The Sundial Bridge is a cantilever spar cable-stayed bridge
for bicycles and pedestrians that spans the Sacramento River
in Redding, California
, United States
and forms a large sundial
. It was designed by Santiago Calatrava
and completed in 2004 at a cost of US$23,500,000. The bridge has become iconic for Redding.
, a complex containing environmental, art and history museums and the McConnell Arboretum and Gardens. It also forms the gateway to the Sacramento River Trail, a 35-mile-long trail completed in 2010 that extends along both sides of the river and connects the bridge to the Shasta Dam
. Drift boats of fishermen are often seen passing beneath the bridge as they fish for salmon, steelhead and rainbow trout. In the distance, Mount Shasta
is barely visible. Shasta Bally is visible to the West looking upstream the Sacramento.
of a sundial; it has been billed as the world's largest sundial, although Taipei 101
and the associated sundial design of its adjoining park are much larger. The Sundial Bridge gnomon's shadow is cast upon a large dial to the north of the bridge, although the shadow cast by the tower is exactly accurate on only one day in a year – the summer solstice
, June 21. The tip of the shadow moves at approximately one foot per minute so that the Earth's rotation about its axis can be seen with the naked eye.
in Seville
, Spain (1992). This type of bridge does not balance the force
s by using a symmetrical
arrangement of cable
forces on each side of its support tower; instead, it uses a cantilever
tower, set at a 42-degree angle and loaded by cable stays on only one side. This design requires that the spar resist bending
and torsional forces and that its foundation
resists overturning. While this leads to a less structurally efficient structure, the architect
ural statement is dramatic. The bridge is 700 feet (213 m) in length and crosses the river without touching the water, a design criterion that helps protect the salmon spawning grounds beneath the bridge. The cable stays are not centered on the walkway but instead divide the bridge into a major and minor path.
The cable for the bridge totals 4,342 feet and was made in England. The dial of the sundial and a small plaza beneath the support tower are decorated with broken white tile from Spain. The bridge's deck is surfaced with translucent structural glass from Quebec, which is illuminated from beneath and glows aquamarine at night. The steel support structure of the bridge was made in Vancouver, Washington
and transported in 40-foot sections by truck to Redding.
as another architectural marvel, and it has been successful in that goal.
Cantilever spar cable-stayed bridge
A cantilever spar cable-stayed bridge is a modern variation of the cable-stayed bridge. This design has been pioneered by the architect Santiago Calatrava. An example of this type is the Puente del Alamillo...
for bicycles and pedestrians that spans the Sacramento River
Sacramento River
The Sacramento River is an important watercourse of Northern and Central California in the United States. The largest river in California, it rises on the eastern slopes of the Klamath Mountains, and after a journey south of over , empties into Suisun Bay, an arm of the San Francisco Bay, and...
in Redding, California
Redding, California
Redding is a city in far-Northern California. It is the county seat of Shasta County, California, USA. With a population of 89,861, according to the 2010 Census...
, United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and forms a large sundial
Sundial
A sundial is a device that measures time by the position of the Sun. In common designs such as the horizontal sundial, the sun casts a shadow from its style onto a surface marked with lines indicating the hours of the day. The style is the time-telling edge of the gnomon, often a thin rod or a...
. It was designed by Santiago Calatrava
Santiago Calatrava
Santiago Calatrava Valls is a Spanish architect, sculptor and structural engineer whose principal office is in Zürich, Switzerland. Classed now among the elite designers of the world, he has offices in Zürich, Paris, Valencia, and New York City....
and completed in 2004 at a cost of US$23,500,000. The bridge has become iconic for Redding.
Location
The Sundial Bridge provides pedestrian access to the north and south areas of Turtle Bay Exploration ParkTurtle Bay Exploration Park
Turtle Bay Exploration Park, located in Redding, California, is a museum complex that interprets the relationship between humans and nature. The attractions include a botanical garden, a natural history and science museum, a "camp" for nature, history and science education programs, and seasonal...
, a complex containing environmental, art and history museums and the McConnell Arboretum and Gardens. It also forms the gateway to the Sacramento River Trail, a 35-mile-long trail completed in 2010 that extends along both sides of the river and connects the bridge to the Shasta Dam
Shasta Dam
Shasta Dam is an arch dam across the Sacramento River in the northern part of the U.S. state of California, at the north end of the Sacramento Valley. The dam mainly serves long-term water storage and flood control in its reservoir, Shasta Lake, and also generates hydroelectric power...
. Drift boats of fishermen are often seen passing beneath the bridge as they fish for salmon, steelhead and rainbow trout. In the distance, Mount Shasta
Mount Shasta
Mount Shasta is located at the southern end of the Cascade Range in Siskiyou County, California and at is the second highest peak in the Cascades and the fifth highest in California...
is barely visible. Shasta Bally is visible to the West looking upstream the Sacramento.
Sundial
The support tower of the bridge forms a single 217 foot (66 metre) mast that points due north at a cantilevered angle, allowing it to serve as the gnomonGnomon
The gnomon is the part of a sundial that casts the shadow. Gnomon is an ancient Greek word meaning "indicator", "one who discerns," or "that which reveals."It has come to be used for a variety of purposes in mathematics and other fields....
of a sundial; it has been billed as the world's largest sundial, although Taipei 101
Taipei 101
Taipei 101 , formerly known as the Taipei World Financial Center, is a landmark skyscraper located in Xinyi District, Taipei, Taiwan. The building ranked officially as the world's tallest from 2004 until the opening of the Burj Khalifa in Dubai in 2010...
and the associated sundial design of its adjoining park are much larger. The Sundial Bridge gnomon's shadow is cast upon a large dial to the north of the bridge, although the shadow cast by the tower is exactly accurate on only one day in a year – the summer solstice
Solstice
A solstice is an astronomical event that happens twice each year when the Sun's apparent position in the sky, as viewed from Earth, reaches its northernmost or southernmost extremes...
, June 21. The tip of the shadow moves at approximately one foot per minute so that the Earth's rotation about its axis can be seen with the naked eye.
Design
The Sundial Bridge is a cantilever spar cable-stayed bridge, similar to Calatrava's earlier design of the Puente del AlamilloPuente del Alamillo
The Alamillo Bridge is a structure in Seville, Andalucia , which spans the Canal de Alfonso XIII, allowing access to La Cartuja, an island between the canal and the Guadalquivir River. The bridge was constructed as part of infrastructure improvements for Expo 92, which was held on a large site on...
in Seville
Seville
Seville is the artistic, historic, cultural, and financial capital of southern Spain. It is the capital of the autonomous community of Andalusia and of the province of Seville. It is situated on the plain of the River Guadalquivir, with an average elevation of above sea level...
, Spain (1992). This type of bridge does not balance the force
Force
In physics, a force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape. In other words, a force is that which can cause an object with mass to change its velocity , i.e., to accelerate, or which can cause a flexible object to deform...
s by using a symmetrical
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...
arrangement of cable
Cable
A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...
forces on each side of its support tower; instead, it uses a cantilever
Cantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...
tower, set at a 42-degree angle and loaded by cable stays on only one side. This design requires that the spar resist bending
Bending
In engineering mechanics, bending characterizes the behavior of a slender structural element subjected to an external load applied perpendicularly to a longitudinal axis of the element. The structural element is assumed to be such that at least one of its dimensions is a small fraction, typically...
and torsional forces and that its foundation
Foundation (architecture)
A foundation is the lowest and supporting layer of a structure. Foundations are generally divided into two categories: shallow foundations and deep foundations.-Shallow foundations:...
resists overturning. While this leads to a less structurally efficient structure, the architect
Architect
An architect is a person trained in the planning, design and oversight of the construction of buildings. To practice architecture means to offer or render services in connection with the design and construction of a building, or group of buildings and the space within the site surrounding the...
ural statement is dramatic. The bridge is 700 feet (213 m) in length and crosses the river without touching the water, a design criterion that helps protect the salmon spawning grounds beneath the bridge. The cable stays are not centered on the walkway but instead divide the bridge into a major and minor path.
The cable for the bridge totals 4,342 feet and was made in England. The dial of the sundial and a small plaza beneath the support tower are decorated with broken white tile from Spain. The bridge's deck is surfaced with translucent structural glass from Quebec, which is illuminated from beneath and glows aquamarine at night. The steel support structure of the bridge was made in Vancouver, Washington
Vancouver, Washington
Vancouver is a city on the north bank of the Columbia River in the U.S. state of Washington. Incorporated in 1857, it is the fourth largest city in the state with a 2010 census population of 161,791 as of April 1, 2010...
and transported in 40-foot sections by truck to Redding.
Budget
Plans for the Sundial Bridge began in the 1990s, when the city of Redding budgeted $3 million for a pedestrian bridge across the river. However, costs escalated after Calatrava's design was chosen in 1996, and the project became a controversial one within Redding, supported by a small group of doctors, lawyers, and other professionals but opposed by other residents who thought it would be too expensive and who favored a more "folksy" covered bridge design. The bridge was completed in 2004, three years later than originally planned, at a cost of $23.5 million, with funding from the Redding-based McConnell Foundation. The expense was justified on the basis that it would increase tourism in the Redding area, which also features Shasta DamShasta Dam
Shasta Dam is an arch dam across the Sacramento River in the northern part of the U.S. state of California, at the north end of the Sacramento Valley. The dam mainly serves long-term water storage and flood control in its reservoir, Shasta Lake, and also generates hydroelectric power...
as another architectural marvel, and it has been successful in that goal.