Backtalk 04/10/2008

Extreme engineering The nation's largest and most complex engineering project was Boston's "Big Dig." The project, which took nearly 30 years and exceeded $14.6 billion, was built to untangle an extraordinary traffic mess that worsened each year. The Central Artery, a six-lane elevated highway, opened in 1959 and comfortably handled the 75,000 vehicles that used it each day. As time went on, the number of cars rose to more than 200,000, making it one of the most congested highways in the U.S. The solution: Replace the highway with an 8-to- 10-lane underground expressway directly below the existing one. The expressway would culminate at its northern limit in a 14-lane, two-bridge crossing of the Charles River. The larger of the two, the Leonard P. Zakim Bunker Hill Bridge, is a 10-lane cable-stayed hybrid bridge. It is the widest ever built and first to use an asymmetrical design. Donated plastic send robots into “overdrive” is continuing its support of the multinational FIRST (For the Inspiration and Recognition of Science and Technology) Robotics Competition by donating plastic machinery components. This year’s game, “FIRST Overdrive,” challenges the more than 1,500 students to build a robot that can carry or kick 40-in. inflated balls around a circular indoor field, as well as knock down and move the balls around the field by passing them over or under a 6-ft, 6-in. overpass constructed of gymnasiumlike rings. Teams earn bonus points by putting the balls back onto the overpass before the 2-min, 15-sec match ends. A platinum-level supplier for three years running, igus has donated Energy Chain cable carriers; iglide J and M250 plastic bearings; iglide MCI plastic clip bearings; igubal spherical bearings, including rod-end, pillowblock, and flange designs; DryLin R linear bearings, DryLin N linear-guide systems, and DryLin S aluminum shafting. Donating these items lets igus promote