ACPA Concrete Pavement Progress Q1 2020

Concrete Pavement Progress www.acpa.org 12 WHEN KANSAS CITY TIMBER BARON ROBERT ALEXANDER LONG decided to build a giant lumber mill in the 1920s, he decided on a site at the confluence of the Cowlitz and Columbia rivers. Located 67 miles south of Olympia, Wash., the site would become the home of Long-Bell Lumber Companies. Long did not want a haphazardly organized mill town to grow up around the lumber mill, so he designed and financedwhat would become the largest U.S. city to be built with private funds at the time. The city of Longview. The city was incorporated in 1924 and by 1930, its population had grown to 10,700 residents. Today, manufacturing wood and paper products is still the main industry and the population is about 38,000, according to the U.S. Census estimates. City planners built concrete streets throughout the planned community, but instead of square or rectangular, they used hexagonal panels. In a 1924 letter from Assistant Engineer L. A. Perry March to Wesley Vandercook, one of the city’s founders and chief engineer for the Long-Bell Company, he described repeated testing of hexagonal and square panels. He points out that, “…the normal fracture occurring in the square panel is a corner break, which is very hard to treat or patch, and under traffic will settle, causing … breaks to adjacent corners and is otherwise a very bad failure.” He adds that “… the typical fracture in the hexagon panels [divides] the panel squarely in two pieces, causing a long straight fracture which is very easily taken care of…” More important than the type of cracks in each panel, Perry said, was the load required to cause a break. His repeated testing of panels showed that “we have increased the resistance to impairment of pavement [by] 45% and increased the resistance to total destruction [by] 68%merely by changing the shape of the panel and its formation.” Shaped for Long Life Hexagonal Panels Approach a Century of Service By Sheryl S. Jackson