New Research Projects

Sidewalk Smoothness

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.


Chehalem Cultural Center

Chehalem Cultural Center PICP Parking Lot Demonstrates an Attractive Solution for Stormwater Runoff

The Chehalem Cultural Center needed a visitor parking lot that also provided the flexibility for hosting a variety of outdoor events. Serving as the main entrance to the Cultural Center Ballroom, permeable pavers were the answer providing a unique visual and textual richness not typically found on parking lots.

To learn more, download the pdf.


Permeable Pavement Takes on Frankenstorm

PICP Parking Lot Demonstrates an Attractive Solution for Stormwater Runoff

As the Monster Storm called Hurricane Sandy slams the Eastern U.S., permeable interlocking concrete pavement—called PICP—is working overtime to reduce runoff and flooding. Millions of square feet of PICP consisting of durable concrete paving units with permeable joints is receiving rainfall rather than sending runoff to overflowing storm sewers and streams. Located in hundreds of parking lots and some low-speed roads, PICP stores runoff under the concrete pavers and allows infiltration into the soil beneath. This reduces local flooding and property damage.

From North Carolina to New England, many cities have passed ordinances over the past decade requiring reduced stormwater runoff. To meet many of these ordinances, developers switched to permeable pavement often because it was less expensive than directing runoff from roofs and impermeable pavements directly into big detention ponds. The ordinances resulted in hundreds of PICP parking lots with some sidewalks and roads built using PICP.

An example is Richmond, Virginia that has begun converting alleys to PICP in the downtown and in selected neighborhoods that store and infiltrate runoff rather than allow it into the city’s combined sanitary and storm sewer system. Another example is Montgomery County, Maryland, that helps offset homeowner expense to install PICP in driveways throughout selected neighborhoods with storm sewers working at capacity. The County figured that it was less expensive to provide some financial incentive to homeowners to make their driveways permeable than to upsize the neighborhood’s storm pipes, a costly project that only sends more water to flood some other downstream neighborhood.

Homeowners should propose to their local municipalities to pass ordinances that include PICP to reduce stormwater runoff in parking lots and low speed roadways. ICPI has developed a short video that explain the benefits of PICP:


To learn more about PICP, visit our web site.


GaLaBau 2012 Snapshot

With 1,156 exhibitors and almost 62,000 attendees, the biennial GaLaBau 2012 offered a view into new trends for the segmental paving industry. GaLaBau is Europe’s leading trade fair for the design of gardens, landscapes, sports fields, golf courses and playgrounds. Abounding in product and design ideas, the show returned to Nuremberg, Germany, Sept. 12—15, 2012, for its 20th show.

The show featured 12 halls with a comprehensive range of products and applications for design, construction and maintenance of urban green and open spaces. About half of the exhibitors presented construction and maintenance machinery. Some 30 percent offered building materials and the remaining 20 percent displayed specialty products like playground equipment, street furniture, or golf course construction and maintenance equipment. The show included indoor and outdoor exhibits and demonstrations. The show feels like a larger, international version of the Green Industries Expo and Hardscape North America held annually in Louisville, KY, at the end of October.

The show featured 12 two-man teams of technical school landscape/hardscape installer trainees that competed for the title of “German Champion Team.” The dedicated students entered the Germany-wide competition for the “Landscape Gardener Cup 2012”. Each team constructed the same hardscape/landscape design, which was judged based on installation principles.

For more information on the show and exhibitors visit their website.


Tar Heel State Trailblazers

The parking lot for the North Carolina chapter of the American Institute of Architects (AIA) building in downtown Raleigh had to be more than a place to park. The organization’s impeccable 12,000 sf (1,200 m2) headquarters was completed late last year and earned Platinum-level LEED credits. The post-modern building was designed by renowned architect Frank Harmon, FAIA , whose rm won a professional competition for the project in 2008 because it promoted “healthy urbanism.” This is evident inside the building and in the exterior landscaping and parking lot, which together provide exemplary integration of modern design with sustainable practices.

On a site smaller than an acre (0.4 ha), the remaining area around the building needed to accommodate landscaping and a parking lot for 36 cars. This immediately presented a challenge, says Harmon, who turned it into an asset. “We decided to turn this problem into a virtue by making a parking area that could be used for many purposes in addition to parking,” he says. “We called this area the Parking Garden, so it could be used for sculpture exhibits, outdoor movies, street parties, a farmers market and other events connected to the building’s large multi-purpose room.”

This meant the lot not only had to be attractive, it also had to be useable immediately after inclement weather. So, naturally, Harmon selected permeable pavement. And when he envisioned a herringbone pattern using interlocking concrete pavers, the ICPI member contractor delivered.

Over four weeks in December 2011, the contractor installed the 8,200 sf (760 m2) parking lot using permeable interlocking concrete pavers that incorporated some of the building’s blue tones. His crew installed most of the pavers with mechanical equipment to reduce construction time and costs. According to the contractor, mechanical installation of the concrete pavers saved at least a week’s worth of labor costs.

Mechanical installation requires one person operating the machine and one person helping to set and align the pavers on the permeable bedding material. Once the paver joints are filled with permeable aggregates and compacted, the owner has immediate use of the surface. In contrast, pervious concrete requires about a week to cure and porous asphalt at least 24 hours before receiving vehicular traffic.

Not Just A Pavement

Although the mechanical installation saved significant time and money, some of the detail work had to be done by hand to achieve Harmon’s standards for appearance.

To achieve Harmon’s desire for a continuous herringbone pattern, the installation crew stitched the mechanically placed paving layers together. Each square yard (m2) layer has a few half pavers on the layer sides. These half pavers are removed during layer placement, replaced by whole units to continue the herringbone pattern from one layer to its neighbors. This creates a consistent pattern across the surface and suggests a customized appearance.

Adding customization, the contractor gave the lot permanent parking stall stripes by creating them with a different color paver. As a result, the building owner eliminated time and money spent maintaining painted stripes on the lot’s surface. Other permeable surfaces don’t provide this option.

Because of its adaptability, sustainability and increased affordability, permeable pavement has seen a rise in demand every year for the last five years in the region. Frank Harmon hopes that the AIA project will inspire more developers to follow suit and increase that demand even more. “We like to think that our building and landscape raises the standard of sustainable design,” Harmon says. “Being in the capital city and located a few hundred feet from the state legislature, it will, we hope, become a role model.”

Leading By Example

Permeable interlocking concrete pavers have already found their way into other parts of Raleigh, a city where excessive stormwater runoff is one of the most pressing environmental challenges, according to Harmon. Completed in the fall of 2011, the North Carolina Department of Environment and Natural Resources (NCDENR) in downtown Raleigh included a permeable interlocking concrete pavement sidewalk as part of its Green Square Complex, a two-block, multi-use, sustainable urban development that houses the NCDENR headquarters, the North Carolina Museum of Natural Sciences’ Nature Research Center and underground parking for 426 cars.

“This is one of the first installations of a permeable paver system within a public streetscape in North Carolina,” says Jonathan Parsons, a project landscape architect for O’Brien/Atkins, the Durham-based firm responsible for the design of the complex’s sustainable systems. The NCDENR permeable paver project consists of 7,100 sf (660 m2) of sidewalk placed in phases over three months.

“This state agency project clearly sets the example for the rest of the state. They’re incorporating green building principles in a downtown area with far too many hard surfaces,” Parsons says. “Hopefully other urban settings across the state will realize the benefits from these principles.”

A Balanced Environment

Raleigh is typical of most urban areas with expansive suburban development surrounding an urban core. Over the years, development impacted multiple streams within the drainage basin, according to Parsons. “Impacts include sudden changes in flow volume and intensity during rainstorms, plus temperature spikes caused by runoff flowing into the streams from paved areas,” he says.

Raleigh in particular has been slow to accept permeable pavers since the clay soils in this part of the state infiltrate slowly, Parsons says. However, the state as a whole has made significant progress in expanding acceptance of permeable pavement as part of a site’s stormwater management plan.

Between 1999 and 2005, North Carolina State University conducted several studies on permeable pavement for infiltrating stormwater runoff, all of which showed positive performance for runoff reduction. Two of these studies were co-funded by the Interlocking Concrete Pavement Institute. As a result, North Carolina State University faculty convinced NCDENR regulators to accept permeable pavement as a stormwater best management practice in 2006. NCDENR recently released revised design guidelines on permeable pavements. The 40-page document provides pollutant credits and site coverage credits to builders and homeowners for using permeable pavements across the entire state. The 2006 edition only provided such credits to the eastern counties with sandy soils.

Permeable pavement enables larger buildings and more efficient site use because the pavement manages the water on the site. The municipal storm drainage systems see less runoff and that reduces public expenses. For Frank Harmon’s project, the permeable interlocking concrete pavement collects all roof runoff and 90 percent of rainwater stays on the site. “If you stand in a mature mountainside forest as it rains, you’ll notice that 90 percent stays in the forest,” he says. “That’s how nature intends it to be in a balanced environment.”


Tech Spec Update

The Interlocking Concrete Pavement Institute (ICPI) announced updates to two of its popular Tech Spec technical bulletin series. “Tech Spec 10 Application Guide for Interlocking Concrete Pavements” and “Tech Spec 15 A Guide for the Specification of Mechanically Installed Interlocking Concrete Pavements” received significant edits.

Tech Spec 10 is completely revised to be the “starter piece” for design professionals and contractors. Organized in a manner similar to the Construction Specifications Institute (CSI) SpecData™ sheets, the revised Tech Spec demonstrates the range of applications suitable for interlocking concrete pavements and provides essential information on each. The reader is directed to specific ICPI design, installation and maintenance resources for these applications. The bulletin treats interlocking concrete pavement as a pavement system and gives direction on how to adapt that system to specific applications. For that reason, Tech Spec 10 should be the first read among the series of 17 ICPI Tech Spec technical bulletins as free downloads on ICPI website.

The title for Tech Spec 15 was modified to more clearly indicate that the bulletin is about considerations when writing specifications for machine-installed concrete pavers. This method of installation accelerates construction time compared to manual methods, while managing costs and maintaining crew energy. It has been used on countless street, industrial, port and airport projects in North America and overseas. Specifications using this installation method are framed around a method statement where the paver manufacturer, paver installation contractor and testing laboratories provide specific information on the paving and bedding materials, test methods and frequencies, installation methods and measures for documenting project quality control/quality assurance.

The original Tech Spec version was framed from lessons learned on large port paving projects, including the Port of Oakland, CA, built in the early 2000s with approximately 4.7 million sf (470,000 m2) of interlocking concrete pavement for container handling facilities. The updated version provides additional information on placing and stitching paver clusters, i.e., the individual paver layers typically cover a square yard (m2) and consis of 35 to 45 concrete pavers manufactured in the final (or near final) laying pattern. The selection of paver layers and the decision to stitch them together primarily affect installation costs and secondarily, pavement performance. Criteria are provided for when and how to stitch together selected paver layers or clusters.

Download your free copies of the current ICPI Tech Specs today. Visit the ICPI website to learn more.



To maintain its original character, one of only two remaining segmental wood-paved areas in Chicago saw restoration of its original construction. Dating from 1909 and located in the city’s Gold Coast neighborhood along Lake Michigan, the alley is enshrined on the National Register of Historic Places and designated a City of Chicago Historic Preservation Landmark. While not officially one of Chicago Department of Transportation’s 100-plus green alleys designed to reduce stormwater runoff, the alley has some sustainable aspects without official certification from the Forest Stewardship Council.

It took 10 years for the CDOT and the community to undertake the venture, says Michael Lev, vice president of TranSystems, the major consultant for the project. “The traditional thing to do would be to cut everything out and put in a concrete alley, but the community felt strongly that concrete was not the right solution,” Lev says. Instead, CDOT decided to replace the original wood pavers with new ones. The construction team vetted various wood species for the new blocks, first considering used railroad ties but finally deciding on black locust wood due to its durability, density, resistance to insects and rotting, visual appeal and lack of odor.

The base of the alley was another issue. “We thought it was pretty unusual to have poured a concrete base under a wood paver street at that time,” Lev says. Although using the existing base reduced costs and construction waste, he says, it also presented drainage complications. “We actually had to create a permeable paver design, but there was this solid concrete base underneath,” Lev says. “We ended up detailing a pattern of weep holes, which the contractor drilled into the base, to allow water to percolate through the bedding sand and the sand in between the pavers, through some filter fabric, and then through the weep holes,” he says. Obviously, open-graded, highly permeable jointing and bedding aggregates used in today’s permeable interlocking concrete pavements aren’t compatible with wood pavers. While sand isn’t as permeable as open-graded aggregates, the passage of any water through sand joints and bedding certainly contributes a bit to stormwater runoff reduction.

Most importantly, the renovated alley retained its cultural value. The renovation of the century-old alley further confirms Chicago as the birthplace of green alleys before naming them as such. As a testament to the alley’s history and durability, a small portion of its west end remains paved with the original 1909 paver blocks. The project won the 2012 American Public Works Association Project of the Year Historical Preservation category award for projects less than $5 million. A glance back to the past suggests that permeable interlocking concrete pavement assumed a role begun by permeable interlocking wood pavement alleys.


HNA 2012 Awards

Brown Hall, Colorado School of Mines

• Project Location: Golden, CO

Square Feet of Project: 35,000

Contractor: Rocky Mountain Hardscapes, LLP


With the construction of Brown Hall, the intent of the design created a beautiful and compelling pedestrian environment in newly vacated streets in the heart of the Colorado School of Mines campus. This solution also accommodated emergency and service vehicle loads and avoided exceeding historic off-site storm flows, while meeting the campus maintenance requirements for a long-lasting, durable pavement surface. The pavement profile captures water on slopes in places which exceeded 8%. This required site specific detailing, including subsurface check dams and subdrains, since the typical design is for under 5% slopes. The pavement system was designed for partial and full infiltration and in places adjacent to the building a liner was included at the bottom of the profile to protect the building foundation from surface water infiltration. An electric snowmelt system was incorporated into the paver design at building entrances. Paver colors were selected to meet the solar reflectance values allowing the project to achieve the LEED credit SSc7.1 – Heat Island Effect/Non-roof. Other LEED credits toward which the paver system contributed were: Stormwater Management Quantity Control Credit 6.1; Stormwater Management Quality Control Credit 6.2; Regional Materials Credit 5. In order to maintain continuity, designer and contractor collaborated on careful detailing of edge conditions around utility manholes and valve covers to accommodate the paver geometry and layout. Specific layout rules helped the contractor minimize redos and avoid a poor result. Team commitment meant spending time in the field to review the paver installation layout to ensure a quality installation and realize the design intent in a non-modular world. While the goal was LEED Silver, with the contribution of a permeable paver system, Brown Hall achieved LEED Gold certification.


Lake Forest Country Club

Project Location: Hudson, OH

Square Feet of Project: 3,000

Contractor: Rock Bottom Lawn & Landscaping


This project consisted of creating an outdoor event venue accommodating all types of gatherings from weddings to informal lunches. The design creates a functional meeting space that highlights and utilizes the picturesque lakefront setting. While the lake served as a beautiful backdrop to the project, it also created challenges in planning and construction. Excess water and slope down to the lake were resolved by engineered retaining walls and extensive drainage under the patio. A professionally diverse staff planned every aspect of the project, including the water feature, the custom bar and grill, and the carefully selected landscaping. To help reduce the scale of the 3,000 sf (279 m2) patio, it was constructed over a grid pattern, accentuated by key vertical elements such as the fireplace, bar, grill and water feature. An inlay of deep red creates the grid that draws your eye down straight lines toward these focal points. Sinuous walls provide a contrast to the rectilinear pavers. A swimming pool, water slides and lounging deck were completed by a separate contractor. The canopy system requested by the association was uniquely designed to conform to the project layout.



Project Location: Dartmouth, NS

Square Feet of Project: 132,000

Contractor: Cornerstone Interlocking Brick Ltd.


The Dartmouth Crossing is a large retail development in Dartmouth, Nova Scotia. Among the typical big box stores are numerous upscale boutiques. When the architects and developers wanted to give these ‘lifestyle’ stores an inviting and appealing feel, they turned to 132,000 sf (12,263 m2) concrete paver sidewalks. Three challenges separated this project from other jobs. The first challenge was the complexity of the circular patterns and accent layouts. The cobblestone look was achieved by nesting half circles with a fan pattern between them. The amount of cutting involved was substantial as none of the factory-supplied circle kits were designed for this method of installation. The second challenge was the different thickness of the banding and soldier coursing.  At 80 mm thick (as compared to 60 mm for the field), the banding pavers and border details had to be graded, laid, and cut before repeating the same process for the thinner field pavers. The third challenge was a tight timeline. Although the work was spread over three years (2007-09), there was always pressure to complete paving for individual stores for grand openings. The unit paving was always left until the very end for over 50 store openings. The pictures for this entry were taken August 2012, four years after installation. The installation has performed flawlessly and looks great with the “main street” storefront designs.


Glen cove ferry terminal

Project Location: Glen Cove, NY

Square Feet of Project: 9,000

Contractor: KJB Industries, Inc.

Paving StonesAs part of the waterfront revitalization in the City of Glen Cove, NY, a terminal dock was added for a ferry to take passengers from Glen Cove into New York City. The site was a contaminated superfund site and this clean up was a major part of the contract. The project consisted of a concrete bulkhead more than 600 ft (183 m) along the waterfront from which floating docks extend for ferries to unload passengers. The ramps from the dock to the top of the bulkhead are handicap accessible. Between the bulkhead and the parking lot, a landscaped, paver walkway and seating area was constructed. The walkway and parking area has area lighting for night use.


virginia street residence

Project Location: Omaha, NE

Square Feet of Project: 2,500

Contractor: Paver Designs


This two-stage project included a front patio area finished for a family wedding, and a driveway added after the wedding. The driveway was excavated to a depth of 16-18 in. (400-450 mm) and the patio is 12 in. (300 mm) deep. Crushed recycled concrete was used for the base with one inch of bedding sand. After the Mega-Arbel Stone pavers were placed, another inch (25 mm) of base was added for the Dublin Cobble paver areas. Holland stone pavers are usually used for the inlays. Three round seats were built next to the water feature and pebble designs were created in the center of each. Columns for the freestanding wall were designed with recessed areas for lights and for use as planters. Three-by-six inch (75 x 150 mm) Dublin cobble pavers were cut in half for the triple border in the narrower areas of the patio. The front paver entrance is gently ramped with no step for handicapped accessibility. The most difficult stage of this project was drawing over 20 diverse designs over the winter months and then making a final selection. Using the basement floor as a drawing board, the “Y” shaped designs were drawn on Masonite at appropriate angles and distances so that the mirrored pairs nearly touched, and a template was made from this. After laying the field of pavers, the mosaic areas were marked with the template. These pavers were cut out one at a time. All of the colored Holland stone pavers were cut into thirds, and then angles were cut to follow curves. The template was moved and traced 12 times; each triple-row design took eight hours to complete, an approximate total time of 96 hours just for the mosaic patterns. Many additional hours were spent cutting and installing the fish and triple borders. Pavers in the mosaic, as well as the koi and borders, were coated with Techniseal NuLOOK. These colors are rich and bright, well worth the extra effort. Techniseal Color Boost matte finish was applied to the Mega-Arbel Stone on the driveway. No finish was applied on the Dublin Cobble Pavers.



Project Location: Williamsburg, VA

Square Feet of Project: 3,500

Contractor: Mid Atlantic Enterprise, Inc.

PRODUCT MANUFACTURER: Hanson Hardscapes & Rediscapes

The main objective for this project was to turn a disabled American veteran’s unused, hilly backyard into a complete outdoor living destination. This meant creating a functional place for the client’s needs while being an exciting place for his young family to play and entertain. A major challenge in this project was altering the terrain to suit the design plan. The entire backyard had to be clear cut and over 3,000 cubic yards (2,300 m2) of earth removed. Poor drainage was corrected before installing the hardscape. To accommodate the elevation changes of the property and to support an ADA compliant ramp, two walls were constructed using Rediscapes Wall Block. One wall serves as a freestanding retaining wall specially constructed on a large concrete footer and reinforced with rebar and concrete. Everything was custom built including a new deck and pergola to blend the home and hardscape. This included a fully functional outdoor kitchen, a gunite pool and spa large enough to accommodate the client’s ever-growing family, two fire bowls and a fire pit to add the “wow” factor. In addition, a shed was built to complement the home while providing much needed storage space. A full landscape was installed, which included five 25 ft Magnolia trees to provide instant privacy in place of the overgrown woody area. To provide safety at night, the project was completed with strategically placed landscape lighting.


HNA Winner: Brown Hall – Colorado School of Mines

Dr. Dave Warner
Tribal leaders
Village cricket
Young girls
electrical infrastructure
trans-border transportation
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