1923 Uniform system of signs State highway engineers across the country adopt a uniform system of signage based on shapes that include the octagonal stop sign. 1925 Numbering system for interstate highways BPR and state highway representatives create a numbering system for interstate highways. East-west routes are designated with even numbers, north-south routes with odd numbers. Three-digit route numbers are given to shorter highway sections, and alternate routes are assigned the number of the principal line of traffic preceded by a one. 1927 Holland Tunnel Completion of the Holland Tunnel beneath the Hudson River links New York City and Jersey City, New Jersey. It is named for engineer Clifford Holland, who solves the problem of venting the build-up of deadly car exhaust by installing 84 electric fans, each 80 feet in diameter. 1930s (Late) Air-entrained concrete introduced Air-entrained concrete, one of the greatest advancements in concrete technology, is introduced. The addition of tiny air bubbles in the concrete provides room for expansion when water freezes, thus making the concrete surface resistant to frost damage.
1932 Autobahn opens The opening of a 20-mile section of Germany’s fledgling autobahn, regarded as the world’s first superhighway, links Cologne and Bonn. By the end of the decade the autobahn measures 3,000 kilometers and inspires U.S. civil engineers contemplating a similar network. Today the autobahn covers more than 11,000 kilometers. 1932 Autobahn opens The opening of a 20-mile section of Germany’s fledgling autobahn, regarded as the world’s first superhighway, links Cologne and Bonn. By the end of the decade the autobahn measures 3,000 kilometers and inspires U.S. civil engineers contemplating a similar network. Today the autobahn covers more than 11,000 kilometers. 1937 Route 66 completed The paving of Route 66 linking Chicago and Santa Monica, California, is complete. Stretching across eight states and three time zones, the 2,448-mile-long road is also known as "The Mother Road" and "The Main Street of America." For the next half-century it is the country’s main thoroughfare, bringing farm workers from the Midwest to California during the Dust Bowl and contributing to California’s post-World War II population growth. Officially decommissioned in 1985, the route has been replaced by sections of Interstate-55, I-44, I-40, I-15, and I-10. 1937 Golden Gate Bridge The Golden Gate Bridge opens and connects San Francisco with Marin County. To construct a suspension bridge in a region prone to earthquakes, engineer Joseph Strauss uses a million tons of concrete to hold the anchorages in place. Its two main towers each rise 746 feet above the water and are strung with 80,000 miles of cable. 1940 Pennsylvania Turnpike The Pennsylvania Turnpike opens as the country’s first roadway with no cross streets, no railroad crossings, and no traffic lights. Built on an abandoned railroad right of way, it includes 7 miles of tunnels through the mountains, 11 interchanges, 300 bridges and culverts, and 10 service plazas. By the mid-1950s America’s first superhighway extends westward to the Ohio border, north toward Scranton, and east to Philadelphia for a total of 470 route miles. 1944 Federal Aid Highway Act The Federal Aid Highway Act authorizes the designation of 40,000 miles of interstate highways to connect principal cities and industrial centers.
1949 First concrete pavement constructed using slipforms The first concrete pavement constructed using slipforms is built in O’Brian and Cerro Counties, Iowa. 1949 First concrete pavement constructed using slipforms The first concrete pavement constructed using slipforms is built in O’Brian and Cerro Counties, Iowa. 1952 Chesapeake Bay Bridge The Chesapeake Bay Bridge, the world’s largest continuous over-water steel structure, opens, linking Maryland’s eastern and western shores of the bay. Spanning 4.35 miles, the bridge has a vertical clearance of 186 feet to accommodate shipping traffic. In 1973 another span of the bridge opens to ease increasing traffic. By the end of the century, more than 23 million cars and trucks cross the bridge each year. 1952 Walk/Don’t Walk signal The first "Walk/Don’t Walk" signal is installed in New York City. 1956 New Federal Aid Highway Act President Dwight D. Eisenhower signs a new Federal Aid Highway Act, committing $25 billion in federal funding. Missouri is the first state to award a highway construction contract with the new funding. The act incorporates existing toll roads, bridges, and tunnels into the system and also sets uniform interstate design standards. 1956 Lake Pontchartrain Causeway opens Lake Pontchartrain Causeway opens, connecting New Orleans with its north shore suburbs. At 24 miles it is the world’s longest over-water highway bridge. Made up of two parallel bridges, the causeway is supported by 95,000 hollow concrete pilings sunk into the lakebed. It was originally designed to handle 3,000 vehicles per day but now carries that many cars and trucks in an hour.
1960s Reflective paint for highway markings developed Paint chemist and professor Elbert Dysart Botts develops a reflective paint for marking highway lanes. When rainwater obscures the paint’s reflective quality, Botts develops a raised marker that protrudes above water level. Widely known as Botts’ Dots, the raised markers were first installed in Solano County, California, along a section of I-80. They have the added benefit of making a drumming sound when driven over, warning drivers who veer from their lanes.
Do'stlaringiz bilan baham:
|
