It’s sometimes said that prestressed concrete beams used in bridge construction aren’t overly exciting. The truth is, they are used because they are less expensive, more efficient, durable, proven and can expedite opening sooner. Simply said, they are the workhorse of the American bridge system and get the job done!
Forterra produced 40 prestressed concrete beams with a maximum length of 146 feet and a maximum weight of 85 tons for the Southwest Light Rail Transit (SWLRT) Green Line Bridge #27C06 over Prairie Center Drive.
But this isn’t just a boring bridge job. In fact, it’s quite the opposite. First, the bridge isn’t intended for use by automobile traffic – it’s intended to be used by light rail trains. Second, the trains will leave the Eden Prairie station at grade and climb vertically to cross Prairie Center Drive. Third, the bridge curves. The curvature on this bridge is attained by using variable length beams in span to perform as “chords” for the turn.
The bridge was installed over a period of four days. Spans 8 through 17 utilized ten 82-inch beams consisting of over 5,000 linear feet of total girders/beams. More than 60 miles of 0.6” diameter, 270 ksi prestressing strand were used in those ten spans alone.
Speed of construction, low cost, and durability make prestressed concrete beams the number one choice for bridge materials – both highway, and transit. And if that’s not exciting, we’ll take boring any day!