With financial support from ICPI members, this magazine humbly started in 1994 with the idea of featuring innovative segmental concrete paving projects. While featuring residential projects from time to time, the main editorial objective was sharing project experiences that increased engineering design, construction, and maintenance know-how for interlocking concrete pavement (ICP), permeable interlocking concrete pavement (PICP), segmental concrete paving slabs, and concrete grid pavements.
This 100th issue highlights the past 25 years. Space doesn’t allow display of all the engineering innovations and visual fireworks in all 100 issues. Many engineers, landscape architects, architects designed, and skilled contractors built some unique, groundbreaking projects. Moreover, willing, and in some cases daring project owners paid for them.
Sea-to-Shining-Sea Pavers—The first issue featured about 330,000 sf of interlocking concrete pavements installed at Berth 30 at the Port of Oakland, California. Like the Port of Baltimore, Maryland, the initial Oakland ICP project led to 5 million sf. Baltimore’s initial project in 1989 of of 230,000 sf eventually led to a total of 2 million sf there.
As the masters of ports with ICP, the Dutch began placing acres in the Port of Rotterdam in the mid-1980s. The total is likely around 20 million sf today. The Baltimore and Oakland projects received inspiration from Dutch pavement engineers. In the case of Baltimore, the engineer who designed the pavers for the European Container Terminus at the Port of Rotterdam provided design guidance to the Port of Baltimore. For Oakland, a Dutch engineer working for the Port at the time helped move ICP forward.
Traffic calming is one of the primary safety benefits of segmental concrete pavements. ICP at intersections in Vieux-Limoilou next to Quebec City, Canada, was selected to slow drivers. Colored, cast-in-place concrete was rejected in favor of the distinct visual appearance of texture change required to warn drivers, as well as ICPs ease of utility repairs. This was the first of several traffic calming projects reported in this magazine. This issue was also the first one to show PICP, mostly applications in Germany where the idea began.
Since 1995, the magazine published winners of a design contest most years. The initial national contest was run jointly with Concrete Products magazine. In 2008, ICPI opted to run it’s own contest as part of the Hardscape North America trade show. No matter the sponsor, the winning entries each year consistently revealed innovative designs. The contest winner on the cover of this issue featured a non-repeating paver pattern resembling African Kente cloth. Built under a Metro station in the Overtown neighborhood in the city of Miami, Florida, concrete pavers met the need to construct the 23,834 sf project within three months and at a reasonable cost.
The Port of New Orleans, Louisiana, placed 25 acres of ICP in their Nashville and Louisiana Avenue container terminals which inspired the Port of Tampa, Florida, to install 18 acres in Berth 208 for bulk steel storage. Life cycle cost analysis by the Port of New Orleans demonstrated the lower overall costs for ICP on a cement-treated base compared to unreinforced and reinforced concrete pavements. A consultant’s study for the Port of Tampa demonstrated that ICP on a thick aggregate base reinforced with geogrid would be sufficient to support heavy plates and rolls of sheet steel compared to asphalt pavement. Machine-assisted installation was used in both projects.
Across North America, increasing flood occurrences are damaging roads and shortening their life. The Forks cultural center near downtown Winnipeg, Manitoba, at the confluence of the Assiniboine and Red Rivers demonstrated the ability of ICP to resist damage from inundation. Some of the 200,000 sf rest on concrete docks along the Assiniboine River. They are covered each winter by rising waters for about eight weeks. When the flood waters recede, the fire department washes them clean, making the pavers ready for the spring and summer events. The flood-resistant mechanics of ICP are simple: the sand-filled joints between the pavers relieve water pressure in the saturated bedding sand. With rising sea levels and increasing damage to local roads from flooding, a resilient solution appears to be demonstrated here. In the meantime, the pavers visually unite various buildings.
Two elegant acres of a jazzed paver pattern graces the entrance to Canada’s National Trade Centre in downtown Toronto. Having done similar, smaller paver pattern designs for other municipalities, the Toronto project became the apogee of art professor Jerry Clapsaddle’s visual treats in unit concrete paving. While the paver waves reflect the shore of nearby Lake Ontario, the design came from exploration of computer-generated patterns. With the help of invisible rays from the Buck Rogers architecture, the pavement’s energy level has yet to be matched by other ICP projects. It resonates without making a sound.
A new international airport for Hong Kong rests on an island near the city. Since there wasn’t quite enough land on the island for the airport, one of the island’s mountains was removed and cast into the sea to create the land. Expected pavement settlement was addressed with about 5 million sf of concrete ICP around part of the passenger terminal and cargo buildings. Installed on a cement-treated base, pavers enabled easier of repairs with reduced down times compared to rigid concrete pavement. Inspired by other overseas airfield projects and by ICPI’s Airfield Pavement Design with Concrete Pavers manual, the Hong Kong project remains the largest installation of ICP in an airport. ICPI later published a case study on the project in cooperation with the British contractor, John Howe, and Interpave UK.
September 30, 1999
At a meeting with ICPI members, the U.S. White House Office of Management and Budget revised the Department of Labor’s Bureau of Labor Statistics Standard Occupational Classification to include a new occupation called Segmental Pavers. The classification number is 47-4091 and the occupation is defined as one who “lays out, cuts, and places segmental paving units. Includes installers of bedding and restraining materials for the paving units.” With some 7,000 years of history, it was good to see the United States government recognize this ancient occupation.
At 5 million sf, the Port of Oakland Berths 55 through 59 achieves the record for the largest ICP project in the Western Hemisphere. ICP was selected because the pavement was built on about 2 million cubic yards of fill soil that presented some risk of differential settlement over time. Compared to other surfaces, ICP could tolerate some deformation and still be serviceable. The pavement could also likely survive earthquakes. “Fill” also consisted of demolished buildings of a former WWII U.S. Navy base. The pavement structure consisted of 100 mm thick pavers on an inch of bedding sand over 3 inches of asphalt and 18 inches of Caltrans Class 2 aggregate base. Tenant Hanjin Shipping Company, Ltd., wanted ICP because it could support various heavy container handling equipment such as top pick machines and rubber-tired gantries.
While acres of ICP in plazas and streets surround the Rock and Roll Hall of Fame in downtown Cleveland, Ohio, this issue featured a groundbreaking, high-slope, 350,000 sf street project in Colma, California. See page 25 for a follow up article 18 years later. The residential streets and sidewalks demonstrated that ICP could maintain a stable surface at an 18% slope. Sometimes a concern of fire departments, the project increased confidence in using pavers in steeply sloped paver driveways and streets.
As previously noted, 1989 marked the first use of 230,000 sf of ICP in a wharf at the Seagirt Marine Terminal at the Port of Baltimore, Maryland. This project was inspired by 660,000 sf of ICP placed in 1983 at Massey Coal Terminal (now Pier IX) in Newport News, Virginia. This issue documented projects at the Port of Baltimore, all totaling almost 2 million sf. The applications included container yards and a roll-on/roll-off (aka ro-ro) facility that receives heavy wheeled equipment and steel-tracked vehicles. The ro-ro areas were created by removing existing asphalt and paving an inlay of concrete pavers and bedding sand.
The passage of the Americans with Disabilities act in the early 1990s led to development of design guidelines for the public-right-of-way proposed by the U.S. Access Board in 2000. With no technical justification, pavers were disqualified from sidewalks in the proposed guidelines due to wheelchair user discomfort from vibrations. This motivated ICPI and the Brick Industry Association (BIA) in 2002 to involve well-known wheelchair researchers at the University of Pittsburgh to test vibrations in wheelchairs passing over jointed, cast-in-place concrete, as well as concrete and clay pavers.
Not surprisingly, the research results indicated that pavers with small or no chamfers enabled a smooth ride for wheelchair users. This research began a supportive relationship with the U.S. Access Board that led to additional industry research in 2004, new surface roughness measurement technology in 2014, an ASTM standard for taking roughness measurements in 2016, and additional roughness research in 2017 that affirmed Access Board roughness criteria recommended in 2018.
While around for decades, this was first issue to recognize the emerging use of segmental concrete paving slabs. The basic difference between a paver and slab is the former can be picked up and placed with one hand; the latter requires at least two. Canadian producers helped moved the slab industry forward by having the Canadian Standards Association publish the initial version of slab standard in 1972 dubbed CSA A231.1 Precast Concrete Paving Slabs. Forty-four years later, the U.S. industry, having grown and learned much from the Canadians, published a product standard through ASTM in 2016 called C1782 Standard Specification for Segmental Concrete Paving Slabs. The ICPI developed detail drawings, guide construction specifications, and Tech Spec technical bulletins that address paving slabs. At this writing, ICPI has drafted structural design guidelines for limited vehicular traffic and is conducting full-scale testing to validate them.
In 1985, the editor (as a municipal employee) orchestrated the design and construction of the first mechanically-installed city street in the U.S., specifically in a historic district in Dayton, Ohio. This issue visited that street 20 years later and, according to the City of Dayton, found that the picturesque street received no repairs for its first twenty years.
Besides the regular circulation, this issue was distributed at the 8th International Conference on Concrete Block Paving in San Francisco during the same month. Sponsored by member donations to the ICPI Foundation for Education and Research, the triennial conference attracted about 400 delegates to hear presentations on 80 technical papers. The issue also covered center-city revitalization in Kingston, Ontario, using pavers, permeable pavement research, and guidelines on selecting bedding sand for vehicular applications, also known as ICPI Tech Spec 17 Bedding Sand Selection for Interlocking Concrete Pavements in Vehicular Applications. Thanks to conference and advertiser support, this issue was the largest at 64 pages.
Traffic calming received additional coverage from the editor’s several visits to the Netherlands with some occurring before ICPI and this magazine started. The 2007 article explained the critical role of concrete pavers in the evolution of traffic calming there. The latest designs were featured as created by Hans Monderman, a traffic engineer from Drachten in the northern part of The Netherlands. Wikipedia captures Mr Moderman’s approach well:
“His most famous approach has been labeled designing for negotiation, which he openly admits works better in some places than others. At busy urban intersections with slow traffic, he has found that it is often safer and more effective to get road users to focus on looking at one another instead of traffic control devices. Rather than crosswalks, signs, lights, etc., he designs the road to make it easier for users to see and negotiate with one another. His goal is to enhance the conspicuity and predictability of users, empowering them to cooperate with each another.”
Thanks to his fewer-signs-is-more-driver-information approach, Mr. Monderman remains a legend in the traffic calming world. With his sudden death in 2008, the editor was thrilled to visit him and tour some of his designs in 2007. Most of his projects relied on ICP to draw driver attention to pedestrians.
With its inaugural show in March 2007 in Nashville, Tennessee, Hardscape North America (HNA) ran a second show there in March 2008. At the time, the small show was fledgling. When HNA co-located in Louisville, Kentucky, with the GIE+EXPO in 2010, a symbiosis occurred by displaying the world of hardscaping to the landscaping industry, and vice versa. HNA since has grown to 166 exhibitors occupying over 46,000 net sf and programs attracting over 3,600 attendees. This is added to some 16,000 attendees at the GIE+EXPO which together is the 13th largest trade show in the U.S. The 2008 HNA show inaugurated the HNA Project Awards contest whose winners presented the finest residential and commercial projects in this magazine for the past ten years.
The U.S. National Pollutant Discharge Elimination System (NPDES) permits in the early 2000s essentially regulated PICP into existence. State and local municipalities, and especially some 772 older cities with combined sanitary and storm sewer systems, developed guidelines for reducing pollutants and stormwater runoff. PICP was recognized as an effective control measure to reach water quality improvement and water quantity reduction goals.
Then the largest PICP project at 265,000 sf, a parking lot at the Chicago White Sox stadium saved the client money by not having to install expensive underground vaults for storing runoff from the 100-year storm. The issue also featured a 140,000 sf PICP parking lot at a commercial redevelopment project in northern Ohio. In addition, an article introduced ICPI’s PICP design software, Permeable Design Pro, available at www.permeabledesignpro.com.
One of the most visible PICP projects opened in 2010 at a U.S. Environmental Protection Agency facility in Edison, New Jersey. The site is a 100-car parking lot with side-by-side monitoring of PICP, pervious concrete and porous asphalt. The main research objective is determining any long-term impacts from pollutants on soils under permeable pavement. Maintenance is also being documented as well as surface infiltration. The project received much press and on-line exposure, and EPA published various reports over the years of monitoring. So far, so good regarding pollutant reductions with regular maintenance and snow removal. The PICP area was expanded in 2016 as part of removing raveled previous concrete.
First documented on the cover of the May 1997 issue, a later phase of sidewalks along Biscayne Boulevard in downtown Miami, Florida, brought the total to about 1 million sf of ICP. Desinged by Brazilian landscape architect Roberto Burle Marx, the bold paver supergraphics suggest the wilder side of Miami with its rich ethnic heritage.
With assistance from ICPI members and the ICPI Foundation, the University of New Hampshire Stormwater Center built a 13,000 sf PICP street and cul-de-sac parking lot and monitored it for over a year to demonstrate that PICP works in cold climates. The year 2010 was also the year the American Society of Civil Engineers released ASCE 58-10 Structural Design of Interlocking Concrete Pavement for Municipal Streets and Roadways. Slightly revised and re-approved in 2016, the standard provides ICP design with aggregate and stabilized bases.
This magazine reported on Toyota’s use of 326,000 sf of PICP at a dealership in Vancouver, Washington. The magazine also gave guidance on ICP crosswalks, sometimes presenting difficult assemblies to design for durable results. This issue summarized results from full-scale load testing of various ICP crosswalks, bases and edge restraints conducted by the University of Waterloo. The research provided design guidance for ICPI Tech Spec 19 Design, Construction and Maintenance of Interlocking Concrete Pavement Crosswalks released in 2014.
Besides covering a few universities (among many) using much ICP for walks and plazas, this issue reported on Charles City, Iowa, placing 170,000 sf of PICP as a first phase in an older residential neighborhood. This saved money by not having to replace and upsize the storm sewer system. A follow up article appeared in the Summer 2014 issue which documented an additional phase, plus other PICP projects in Iowa.
The magazine underwent a name change to Interlock Design and received a layout upgrade. Quarterly issues were designated by season rather than by month. The cover story featured the first PICP alley in Los Angeles which converted a linear dump into a pleasant spot supporting adjacent restaurants and bars. Usually not available to most PICP projects, this one found an opportunity to enhance the existing economic and social culture, one unique to LA’s Hollywood neighborhood.
At 20 years old, this issue provided a brief timeline of the years that led up to the formation of ICPI, as well as the first two decades of ICPI’s progress. In project news, a developer for Whole Foods and Walgreens used 40,000 sf of PICP to prevent runoff from entering the pristine Boise River next to it that also runs through the center of Idaho’s capital city. This was the first PICP project of this size in the state. Not uncommon for PICP projects, it spared a detention pond on the site, thereby enabling additional development land in the future.
The cover story about acres of PICP alleys and streets in three Iowa cities came from an editor’s tour there. Charles City expanded an initial area to cover streets among 27 blocks of an older residential neighborhood. A smaller village, West Union, saw its Main Street downtown paved in PICP. The older city of Dubuque installed a few PICP green alleys as a pilot program and is commencing phased installation of over 200 to reduce combined sewage from entering the Mississippi River.
In response to combined sewer overflows and neighborhood flooding, the City of Atlanta built the largest street installation of PICP at over 700,000 sf to store and infiltrate stormwater. The multi-phase project was part of the Southeast Atlanta Green Infrastructure Initiative. The $66 million invested in PICP eliminated flooding and raised property values in older residential neighborhoods. ICPI also created a case study on the project as shown below.
With the post-recession residential market surging, this issue presented a fine example of complete backyard room. Two projects were revisited tracking 30-plus year of ICP performance: downtown North Bay, Ontario, and Tecumseh Street in Dayton, Ohio. A 2016 visit by the editor to the latter showed that the cast-in-place concrete installed at the same time as the ICP in 1985 was showing serious signs of cracking and wear. The concrete pavers were fine, continuing their compliant adjustment to minor settlement and in a few small areas and where the base was weakening, all while remaining serviceable. The editorial addressed the age-old, common misconception that H-20 loads are relevant to pavement design. Don’t be fooled; such loads are used in bridge design only.
After reporting the project in the November 2000 issue, this issue returned to Colma, California, to visit its 20-year old residential ICP streets. The editor found them almost in the same condition as when installed, and with essentially no maintenance. The same town public works director who oversaw the street and sidewalk installation in 1997 was still employed. He reflected on the life cycle costs compared to asphalt. He noted that in Colma’s moderate climate and residential traffic, ICP would have a lower life-cycle cost than asphalt after about 30 years. The ICP will reach that goal. He did note that seal coating as well as milling and replacing asphalt interferes with traffic and residents’ schedules. ICPI has none of that.