The Long and Quiet Road

The Natural Rubber Bureau Research Laboratory was a facility that conducted experiments in the 1950s to prove the viability of rubberized roads by embedding rubber in asphalt across the U.S. and Canada. The findings were published in the report “Stretching Highway Dollars with Rubber Roads” (1952). These studies demonstrated that such roads were longer-lasting, safer, slower to freeze, and less brittle below freezing than ordinary asphalt. The pavement provided better skid resistance and produced fewer cracks when compared to concrete, reducing maintenance costs for highway departments. 

The tests were part of a broader historical timeline of mixing rubber and asphalt dating back to the 1920s and earlier experiments in the Netherlands, confirming similar benefits. By 1954, the Bureau of Public Roads had also published laboratory studies evaluating various rubber powders, including those from scrap tires, styrene-butadiene rubber (SBR), and natural rubber, further validating the technology. 

Today, Rubberized Asphalt Concrete (RAC) is a noise-reducing pavement material that consists of regular asphalt concrete mixed with rubber made from recycled tires. It is currently used in many regions, though its use is not universal across America. While historically concentrated in warmer states like Arizona, California, Florida, Texas, and a couple of southeastern states, testing is expanding into northern regions of Washington, Colorado, and Missouri, with recent projects demonstrating improved durability and a quieter driving experience.

Note: Porous Elastic Road Surfaces are a type of low-noise pavement composed primarily of rubber granules, often from scrap tires, and mineral aggregates bound together with polyurethane resin rather than traditional asphalt. This composition creates a highly porous and elastic material that is even quieter, yet it faces challenges regarding durability and bonding.

Hand Me That Wrench

For the 1946 Convair XB-36 prototype, the two main landing gear tires were the largest aircraft tires Goodyear ever made, weighing 1,320 pounds each. The tricycle landing gear setup was used for all larger aircraft at the time, but the immense weight of the largest bomber ever built restricted its landing to just three runways nationwide. That changed with the second pre-production bomber, the YB-36, with the invention of a 4-wheel bogey design with smaller tires, distributing the weight evenly, allowing the plane to land on any major runway. With a few exceptions, this became the new standard for all future large aircraft. Constant upgrades throughout its career were made to keep pace with the speed of the era's aeronautical advancements. The most visible change was the adoption of a new, raised canopy for better pilot visibility, first used on the YB-36. 

Note: The B-36 was the United States Air Force's first true intercontinental bomber, entering Air Force inventory in 1948 and remaining active through 1958. The final flight of the bomber was in the Spring of 1959, delivered to the United States Air Force Museum at Dayton, Ohio for permanent display. Three other B-36s remain in American museums.