ICPI Interlock Design Issue 3 2018

2 David R. Smith interlockutor Missionary Work Continues on page 3 S tate departments of transportation (DOTs) rely on millions of tax dollars for road construction and maintenance. They also look after thousands of struc- tures including bridges. For decades, DOTs are immersed—and one might say entrenched—in design, mainte- nance and improvement of asphalt and concrete pavements. These are mostly highway pavements. Most DOTs look after local roads as well, especially if they are national or state routes passing through a city or town. About one fourth of all roads are urban, so some portion of this percentage is under state DOT care. While the percent- age of their total road inventory likely varies from state-to-state and province- to-province, urban roads represent an opportunity for interlocking concrete pavements (ICP). Here is a story from the New York State DOT (NYSDOT) who made a new path for ICP. In 2004, the U.S. Federal Highway Administration contacted the NYSDOT requiring removal of ICP from pavement use due to crosswalk failures. This was likely due to problems from a federally funded road project. In the fall of 2005, at the request of ICPI, a task force was created to implement new specifications and subbase requirements to allow ICP. In 2006, provisional ICP specifications were written with drafts of typical sections for ICP crosswalks in high use areas. The drafts included a 12-inch thick crushed stone subbase, 8 inches of con- crete, ¾ inch sand-bitumen setting bed and adhesive under 3 1/8-inch thick (80 mm) thick pavers in a herringbone pat- tern. The paver thickness was increased from 2 3/8 (60 mm) to 3 1/8 inch as recom- mended by ICPI. The NYSDOT found a trial location, where a crosswalk(s) in a street could be built. The street had about 8,000 average annual daily traffic (AADT) and this provided a pilot project to monitor the success of the draft speci- fications. In 2007, the State Historic Preserva- tion Society decided that ICP must be used to replace the pavement on Main Street in East Aurora, NY. AADT was over 20,000 with 10% to 12% truck traffic. This equates to roughly 10 million equivalent single axle loads (ESALs) over 20 years Four blocks of interlocking concrete pavement are paved on Main Street in East Aurora, New York in 2009.