The U.S. Access Board is currently researching smoothness criteria with the help of the University of Pittsburgh’s Human Environmental Research Laboratories. The criteria are being developed by the University from wheelchair user surveys, extensive data on wheelchair use patterns and roughness measurements. The intent is to develop smoothness criteria that eventually may be included in national Americans with Disabilities Act (ADA) Design Guidelines or in an ASTM standard. These eventual criteria rationalize wheelchair user comfort and sidewalk accessibility.
As a parallel project, ICPI Foundation for Education and Research joined with the Brick Industry Association (BIA) to fund development of a sidewalk smoothness measurement device by the University of Pittsburgh. This University is the same one that conducted wheelchair-pavement interaction studies for ICPI and BIA in 2002 and 2004. The University is completing laboratory and in-situ pavement surface measurements, data analysis and recommended smoothness thresholds. They have begun development of a portable technology for smooth measurement capable of being operated by technician level personnel. The measurement device should be prototyped and tested by summer 2013.
PICP Structural Testing
As a pressing need for PICP market development, structural testing and validated design charts rank high. To address this need, the ICPI Foundation, the California Nevada Cement Association, and the Concrete Masonry Association of California and Nevada co-funded full-scale structural testing and development of design charts for PICP. Modeling, plus laboratory and full-scale load testing of PICP will be done by the University of California Pavement Research Center (UCPRC) in Davis. The ICPI Foundation support includes some of the project costs, a construction test area and project administration. Additional Foundation support includes review of the test program deliverables and review of the data for application to freeze-thaw areas by an outside consultant. About 2,800 sf (280 m2) of permeable pavers are being donated by an ICPI member for the test area. The photo below shows the specialized equipment that repeatedly applies wheel loads while measuring stresses and strains within various pavement structures. The project is expected to start in November 2012.
PICP Cold Climate Research
The ICPI Foundation recently co-founded a permeable interlocking concrete pavement (PICP) parking lot being monitored by the Toronto and Region Conservation Authority (TRCA). This is a continuation of monitoring porous asphalt, pervious concrete and PICP at the offices near Toronto. The funds leverage other contributors who, along with ICPI, helped launch monitoring
over two years. The additional funds extend monitoring another two years. The two PICP parking lot installations at TRCA offices utilize pavers from ICPI Foundation donors.
As previously reported in this magazine, TRCA published very useful PICP reports on monitoring a heavily used PICP parking lot, asphalt parking lot and bioswale at a community college between 2005 and 2008. The reports demonstrated the ability of PICP to reduce runoff and pollutants in a cold climate while confirming lower use of deicing materials than with conventional pavements. A reason for this second monitoring project at TRCA facilities is that the permeable pavement cross sections being tested are those typically recommended by each industry. This side-by-side performance evaluation of PICP, pervious concrete and porous asphalt will be important to furthering PICP in Ontario, wider Canada, and in cold climate regions in the U.S.
PICP Nutrient Reduction Research
The ICPI Foundation is supporting a proposal from North Carolina State University (NCSU) to monitor a small PICP parking lot on low infiltration soils owned by the City of Durham, NC. The US EPA, the City of Durham and an ICPI member are also supporting this project. These research results may likely provide data on nutrient reductions through detention/de-nitrification via a raised subbase underdrain. A raised drain means that runoff can pond within the open-graded base reservoir, and through anaerobic processes, experience greater nutrient reduction than if simply exiting a pipe along the bottom of the base. The project deliverables will help answer questions from stormwater agencies about nutrient reduction on low infiltration clay soils. The research project also has a high impervious surface to receiving PICP surface ratio (6.5:1). The research will examine the rate of sediment accumulation and potential effects on surface infiltration. In the past, ICPI supported NCSU for PICP surface infiltration and water quality/quantity research. This new project starts in fall 2012, and monitoring will continue for two years.