In this industry, the material suppliers drive the segmental retaining wall (SRW) business; a very young, isolated and small segment of the construction industry. At the current level of SRW industry maturity, those driving the business focus on square meters of wall facing and geosynthetics sold. Those driving the business also seek out small contractors that can be manipulated to build walls in accordance with the system providers' specific installation requirements and at their direction. Often, the recommendations of the system provider conflict with those that appear in national peer reviewed articles and documents. Woefully lacking in this scenario is the offering of professionally engineered walls installed by experienced, can't-be-manipulated, professional contractors under the care and control of those familiar with SRW regulation and inspection. Simply stated, there is no broad competence in block and wall design, neither is there comprehensive installation or broad design review/inspection competence. A SRW structure is as critical as a frame for a house and should be treated with the same level of respect and competence, however, it is not. This backwards industry integration and lack of direct involvement from the major general contracting firms has led to too many unnecessary failures and the lack of timely installations; both of which are jeopardizing a successful future. Involvement by major general contracting firms would carry a higher implied "approval" rating of SRW technology and move the technology into large public and private projects, including the highway segments of the various departments of transportation. The SRW industry does not have to languish. A very comprehensive guidance document and design manual exists which, if followed, will correct many problems referenced above. Unfortunately, the majority of the industry does not follow the guidance provided by the NCMA design manual (1). Theoretical and Practical Education The responsibility for inspecting the final product is left to the soil engineers' representative, the on-site soils technician. While the soil tech is probably the lowest paid of the contracting and engineering group, the soil tech carries a large amount of authority relative to influencing the quality with which the wall gets built and affecting the progress and the construction economics of the contractor. Like the engineer, the soil technician typically doesn't understand the system, has little "back-up" from the supervising engineer, and is left to his own devices to do what is "right." Ultimately, the wall gets built with little guidance or recognition of potential problems, which may result in serious long-range adverse effects. There are very few, if any, universities offering classes in SRW design. Likewise, there is little formal training available which focuses on SRW installation. The result is that most engineers don't understand SRW structures, are reluctant to incorporate or design them into their projects, and are uneasy about what is critical in the quality control phases of wall installation. The design and field related problems resulting from inexperience, poor supervision, and inadequate training can be eliminated by requiring theoretical and practical experience of the designers, contractors, and inspectors. System Development Most of the SRW providers have evolved from the block/geosynthetic manufacturing and marketing industry and have very limited competence in SRW design or construction. While there is an abundance of expertise available relative to masonry unit and geosynthetic manufacturing and marketing, little expertise exists in the areas of SRW assembly, site development and construction. Hence the focus of the SRW industry has been to develop and patent unique products, set up and license distributors, and market the systems to those that have the authority to specify them. This often leads to development of systems which look good on paper, are lucrative to manufacture and market, can pass the muster of "standard" laboratory tests, are readily "sold" to the specifier, but are difficult or impractical to install efficiently, correctly or economically. Development of optimized systems needs to occur via cooperation between the general contractors, engineers and material producers/suppliers Development of systems by a cooperative effort as noted above would speed up the development of the SRW sector, increase the long-term reliability of the structure, and enhance understanding for scheduling, construction contracts, installation techniques, speed, and other needs required by the general contractors, developers and owners. Design and Plan Check Current SRW design and plan checking is highly influenced by the material suppliers. Often the system suppliers are offered the opportunity to provide a vendor design or design-build option. While this avenue offers the apparent credibility of having the system "experts" involved in the design phase, it also puts the system provider in a position fraught with conflict; a skimpy design likely ensures initial low costs and sales success; a conservative design is initially more costly and reduces the potential for corporate revenue. The wall designer and the soils engineer of record should be involved and held accountable in the selection of system as indicated by their professional written certification of the system. They need to shepherd the project through its total development process that includes strongly influencing the owner to consider the quality of the whole package offered, not just pricing. Designs should strictly adhere to a specified nationally recognized standard, such as the NCMA or other recognized document. The construction related design assumptions employed in the design process should be stated in the construction notes. The NCMA manual does a good job of providing guidance on the specification related items that should be included on the construction drawings. Some critical compaction related notes include assumptions relative to backfill compaction (including the drainage fill), extent of compacted soil limits (from back-cut all the way to the back of the blocks), compacted lift thickness (lift thickness equal to block height not to exceed 25 cm (10 inches), and other project-specific criteria such as those specified in the NCMA manual. Plan Checking Plan checking of SRWs are typically done in either the building or grading departments. The building department normally focuses on structural issues and is staffed with structural and mechanical type engineers while grading divisions focus on geotechnical issues and possess strong geotechnical resources. SRWs are geotechnical structures. Therefore, they should be incorporated into the plan check and review process as a mandatory requirement in obtaining a grading permit from the grading department. Plan checking must review the design, specification, and global project aspects relative to regulatory codes. It should also require that the selected system posses the required certificates, approvals or other special permits as well as have the civil and geotechnical engineers of record written certification on the proposed design and system employed. Wall Project Integration Subsequent to the grading contractors efforts, the wall contractor mobilizes to the site to construct the walls, then the grading contractor returns to finish the slopes and pads that are invariably above the walls. The critical path schedule for this system requires that the rough grading, wall construction and slopes/pads be done as separate, sequential operations. An integrated system, which enables site grading and wall construction to proceed simultaneously, offers concurrent scheduling of two critical path items and shortens the time to finish the building pads. Progressive finishing of building pads enables continuous earth balance (cut/fill) and minimizes the potential for end of construction costly soil import or export operations. It's essential that wall system be constructed rapidly (to keep up with the grading activities) with standard heavy earth moving equipment (integrated into the earth moving operation), and exhibit high form capacity (to resist lateral loads imposed by heavy equipment). Integrating the wall construction with the grading activities enables two critical path items to proceed in parallel, thus severing the time required to deliver the site to the other building trades. Compaction Related Settlements Several system providers recommend the use of clean crushed rock and filter fabric behind the wall face. While the clean rock is often justified as a drainage layer, it's less often admitted purpose is to avoid the application of compaction stresses near the back of the facia unit. Such compaction stresses have a tendency to push the units outward. In an effort to avoid pushing the SRW units outward, compaction is neglected, resulting in poorly compacted drainage fill and the adjacent reinforced soil. Stacking of several blocks prior to infilling is done as a means of construction expedience. Filling multiple stacked units often results in void spaces and poorly compacted unit infill. In severe cases, some units are left totally empty with large void areas into which adjacent unit fill, drainage fill and reinforced soil can move. When either of the above two scenarios occur, inadequate near facia compaction and poor unit fill result. An increased potential is developed for distress causing latent settlement of unit fill, drainage fill and near facia infill soil. In addition, facing-geosynthetic connection integrity is compromised (normal force and friction decreases) and the system starts to unravel. System providers must produce products, that can tolerate compaction of SRW infill and drainage materials placed immediately adjacent to the facia (as required by the design manuals) without fear of pushing the uppermost blocks outwards. Contractors can't be expected to achieve proper compaction if the blocks move outwards.; neither can they be expected to accept total blame for poor compaction when the system provider has failed to provide a system which can't resist the normal rigors of construction. An immediate suggestion to counter the problem of unit stability during construction is to address the issue of system "form capacity".-is the capacity of the system's top blocks to resist construction-related lateral loads without excess lateral deformation. Systems that don't have the benefit of fully mechanical connections between blocks and reinforcement can only rely on mechanical shear between blocks, block weight and batter to resist heavy lateral live- loads due to compaction stresses and heavy earth moving equipment. Friction between the uppermost block and the reinforcement will be minimal due to low normal force. The problem of low normal force with high compaction stresses exists from the first block laid at the bottom of the wall all the way to last block laid at the top. This is an inherent and permanent problem for the upper wall units, which are particularly vulnerable to near-face traffic loads. Proper compaction of SRW infill soils and drainage fill, as required by nationally recognized documents ,cannot be achieved without a high degree of SRW "form capacity." Call to Action System development with the construction profession in mind will have a good chance to succeed. The industry has access to excellent documents that provide guidance for design and installation. It will not achieve long-term success without building a solid track record based on utilization of existing design/construction guidance and demonstration of thorough competence and integrity. Let us compete while focusing on long-term safety, responsibility, efficient installations and aesthetics, rather than on skimping with cheap designs, poorly trained installation crews, un-proven block systems, and low-priced, untested geosynthetics. SRWs are very economical in comparison with other systems. Credibility, not price, is our challenge. Reference 1. Collin, James G., editor (1997) Design Manual for Segmental Retaining Walls, Second Edition, National Concrete Masonry Association, Herndon, VA, 289 pgs.