The Ribbon of Light, LA City’s Project on Sixth Street Bridge
The original Sixth Street Viaduct opened in 1932 in Los Angeles, connecting Downtown Los Angeles to Boyle Heights. At the time it was the largest and longest of all the bridges in the city. Unfortunately, they didn’t test materials back then, and it was unknown at the time that the materials used to build the bridge would cause a chemical reaction called an Alkali Silica Reaction, which is also known as a concrete cancer. In 1952 the bridge began to crack, and after multiple failed attempts to repair it over the years, it ultimately was deemed seismically deficient, and the decision was made to demolish it.
Fast forward to 2012 when the City of Los Angeles decided to not only replace the bridge with a new, better viaduct, but to hold an international design competition for the right to design it. Ultimately, the winner was design firm HNTB with its design dubbed The Ribbon of Light. It features ten pairs of arches ranging in size from 30 to 60-feet. The bridge will not only have four lanes of traffic like before, but it will have a bicycle lane on each side, 14-foot-wide sidewalks, and five sets of stairs that let pedestrians exit the bridge at different locations. One of the main highlights of the bridge will be the 3 level helical ramp that pedestrians will be able to walk or bike down from the deck level of the bridge. The bridge will also be a special place at night for Angelinos, as the arches will be lit up with color changing LED lights for different events and celebrations.
Once the Sixth Street Viaduct is completed, the Bureau of Engineering will begin construction on the new 12-acre Sixth Street Parc (Parks, Arts, River and Connectivity Improvements), which will rest at the base of the bridge. It will feature soccer fields, basketball courts, a dog park, adult fitness areas, children’s playgrounds and splash pads, a skate park, picnic and garden areas, and an amphitheater.
Of course, any large construction in Los Angeles will have to account for the seismic activity in the area, and the new bridge is no exception. Each column will be equipped with triple friction pendulum bearings, which will allow the entire bridge to move 30 inches in either direction during a seismic event. If there is a seismic event, if there is an earthquake, this is where you want to be. This is going to be one of the safest spots anywhere. The bridge deck construction is scheduled to be completed in summer 2022.