Geotechnical Information Practices in Design-Build Projects (2012)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

56 CHAPTER SEVEN DESIGN-BUILD GEOTECHNICAL CASE STUDIES INTRODUCTION Case study data collection was based on the results of the literature review. The team proposed to identify and ana- lyze at least four projects from across the spectrum of DB transportation projects with geotechnical aspects of spe- cific interest to the synthesis. The cases are separated into geotechnical engineering case studies and geotechnical case law studies. The engineering case studies each high- light a specific geotechnical issue that was solved by means of the use of DB project delivery. Table 32 is a summary of the geotechnical engineering case study projects that were sampled for this research. One can see that the projects span from coast to coast. The team was able to identify and gain access to informa- tion on four geotechnical engineering projects worth more than $600 million in four states that represent the cross sec- tion of variations on DB delivery. The projects ranged from a low of $0.55 million to a high of $483 million. The project types spanned the spectrum from the use of a GBR for an urban elevated guideway project to an emergency repair of a landslide on an interstate highway. GEOTECHNICAL ENGINEERING CASE STUDY PROJECT DETAILS The following sections relate the details of each geotechnical case study project. The objective of this section is to portray the breadth and depth of the case study project population. The format has been standardized for each project to enable each project to be compared with all other projects in the sample. In all cases, the details shown in this chapter were obtained through structured interviews (either in person or by telephone) with the agency and then supplemented as required by specifics found about the project from the literature. West O’ahu/Farrington Highway Guideway Project, Section I—City and County of Honolulu, Hawaii (CCH) The project was selected for inclusion because it illustrates the use of the GBR as a contract document on a DB project that had highly variable subsurface conditions along a sig- nificant project length. The project involved the construction of 6.5 miles of elevated rail guideway resting on columns/ piers spaced at roughly 150 ft. This yields about 220 separate foundations in conditions that included older and recent allu- TABLE 32 SYNTHESIS CASE STUDY PROJECT SUMMARY Agency (case no.) Case Study Project (Value) Construction Type (location) Geotechnical Issue Solicitation Type Payment Provision Type City and County of Honolulu (1) Section I—West O’ahu/ Farmington Highway ($483 million) Elevated Computer Rail Guideway (Honolulu, Hawaii) Use of GBR as contract document RFQ/RFP Lump sum Montana DOT (2) US Highway 2 Rockfall Mitigation ($3.0 million) Rockfall mitigation features (Flathead County, Montana) Adequate slope to pre- vent rockfall can’t be known until construc- tion start RFQ/RFP Lump sum with unit price items Minnesota DOT (3) Hastings River Bridge ($120 million) Steel arch bridge over the Mississippi River (Hastings, Minnesota) Use of preproposal ATCs and PAEs for geotechnical design – resulted in pile-sup- ported embankment w/3-year warranty RFQ/RFP Lump sum Missouri DOT (4) I-270—St. Louis County Slide Repair ($0.55 million) Emergency landslide remediation on inter- state highway (St. Louis County, Missouri) Use of a “nested” DB contract provision in a DBB contract with known geotechnical issues to respond to a major geotechnical problem Invitation for bids with requirement to include a prequalified geotech- nical specialty subcontractor Time and materials

57 vium, localized areas of coralline deposits, isolated boulders and boulder fields, residual soils, and basalt bedrock. Case 1—City and County of Honolulu: West O’ahu/Far- rington Highway Guideway Project Value: $483 million Scope: Design and construction of a 6.5-mile elevated commuter rail guideway. The geotechnical scope work includes the final subsurface investigation and foundation design for approximately 220 column/pier structures that support the elevated guideway. The owner anticipated that drilled shafts would be proposed for the majority of the align- ment because “they can be installed faster; a smaller area of soil is disturbed; and it is quieter than driving piles” (CCH 2008). Figure 7 shows the alignment for the entire corridor project. This case study section lies inside the dotted line. Rationale: The City and County of Honolulu (CCH) chose DB project delivery for this difficult geotechnical project for two reasons. First, it wanted to award the construction as fast as possible to take advantage of a drop in construction costs (Petrello 2009). This was realized when the project came in under the engineer’s estimate. Second, since the alignment was completely through an urban area, CCH was restricted in the amount of preliminary investigation it could do, and as a result it used DB to have competing design-builders optimize the alignment with respect to means and methods, constructability issues such as traffic disruption, and noise mitigation (Dwyre et al. 2010). Procurement: The project used a typical two-step pro- cess, with CCH first issuing an RFQ from which it developed a short list. It then issued an RFP to the members of the short list. The major technical issue that had to be resolved in the development of the RFP was to equitably allocate the risk of differing subsurface conditions. The owner settled on the use of a GBR to mitigate the significant risk of delay and/or cost escalation (Dwyre et al. 2010). Dwyre et al. describe the process used to develop the GBR as follows: A key decision in developing the GBR was that only subsurface material properties would be baselined, and that no baselines would be developed for soil foundation interaction properties. It was not considered feasible or appropriate to baseline parameters such as foundation friction and end bearing values which would be influenced by the contractor’s choice of deep foundation type and the means and methods of installation. Specific parameters baselined in the GBR focused on the factors of greatest significance to the design and construction of foundations, including stratigraphy, groundwater conditions (including an area with confined artesian conditions), USCS soil types, shear strength of cohesive soils, the incidence of cobbles and boulders, clinker zones and voids within the intact basalt, the Rock Quality Designation (RQD) and unconfined compressive strength of the basalt, and seismic site class (Dwyre et al. 2010, italics added). FIGURE 7 Honolulu high-capacity transit corridor project alignment [Source: CCH 2008].

58 Table 33 is a summary of the GBR for the guideway proj- ect. It shows the method the owner’s geotechnical consultant chose to establish the baselines for each soil type. This was developed using preliminary geotechnical data obtained from a boring program with a spacing of roughly one bor- ing every 1,000 ft. Since the design-builder had authority to vary the alignment, this particular data set could easily be off the final alignment. Quality Management: Table 34 shows the distribution of quality management responsibilities among parties to the contract. It shows that the agency’s general engineer- ing consultant was responsible for most of the day-to-day QM tasks. The project also required considerable interac- tion between the design-builder and the agency’s consultant. Note that the two-dimensional Refraction Microtremor (2D ReMi) method was successfully used to map soft soil zones under the Farrington and the Kamehameha Highways, both of which support high traffic volumes, without the need to interrupt traffic flow (Sirles and Batchko 2010). This is another example of innovation that was brought to the proj- ect by the use of DB project delivery. Summary: The project is currently under way. The fact that the award price was 15% less than expected indicates that the use of the GBR as a means to allocate risk was successful. Multiyear DB projects of this magnitude with significant geotechnical risks typically carry large contin- gencies inside the price proposal (Finley 2011). The CCH actually saved $87 million. Although it is impossible to know what percentage of the savings is due to lower con- struction prices, at least some of it must be assigned to a lower design-builder’s contingency owing to the well- defined geotechnical risk. TABLE 34 CITY AND COUNTY OF HONOLULU PROJECT QUALITY MANAGEMENT RESPONSIBILITIES Quality Assurance/ Quality Control Tasks Does Not Apply Agency Design- Builder Agency-Hired Consultant Technical review of construction shop drawings X X Technical review of construction material submittals X X Checking of pay quantities X Routine construction inspection X Quality control testing X Verification testing X Acceptance testing X Independent assur- ance testing/ inspection X Approval of progress payments for con- struction progress X X Approval of con- struction post-award QM/QA/QC plans X X Report of noncon- forming work or punch list X X TABLE 33 SUMMARY OF GEOTECHNICAL BASELINE REPORT BASELINES FOR CITY AND COUNTY OF HONOLULU: WEST O’AHU/ FARRINGTON HIGHWAY GUIDEWAY PROJECT Parameter Stratigraphy Baselines Material Property Baselines Fill As deep as profile line; up to 5 ft deep where not shown • Not baselined. Coralline Undistributed quantity, not shown on subsurface profile • % #200 • % stratum depth cemented • Unconfined strength range Recent Alluvium Suburface profile • USCS types • Average shear strength by station reach Older Alluvium Suburface profile • USCS types • Average shear strength by station reach Cobbles and Boulders Lengths of foundation in cobble/boulder zone • Thickness ranges of clinker and void zones Clinker and Voids Percent of foundations where clinker/voids will be present • Thickness ranges of clinker and void zones Rock Subsurface profile line, with upper/lower bounds for planning construction means and methods • Minimum RQD for specified percentage of core run • UCS Groundwater Elevations Varying groundwater conditions shown on profile • Water table or confined aquifer Source: Dwyre et al. (2010). USCS = Unified Soil Classification System; UCS = unconfined compressive strength; RQD = Rock Quality Designation.

59 US 2 Rockfall Mitigation Project—Montana DOT (MDT) This project was selected for inclusion for three reasons. First, the geotechnical problem that had to be solved was how to quantify a scope of work when the agency does not know the minimum angle of repose for an unstable rock slope, and the angle cannot be found until construction com- mences. Therefore, this represents the high end of geotech- nical uncertainty, and that MDT chose DB project delivery represents an interesting and valuable rationale for projects with high geotechnical uncertainty. The second reason was the mechanism that MDT chose to allocate risk: unit price pay items for the uncertain features of the scope. Finally, MDT developed an innovative approach to getting as much rockfall mitigation completed as possible for the available funding, recognizing that once it had reached the end of the budget, the project was over regardless of how many linear feet of slope had been stabilized. Case 2—Montana DOT: US 2 Rockfall Mitigation Proj- ect, Flathead County Value: $3.0 million Scope: Design and construction of rockfall mitigation measures and slope stabilization along 14 miles of US High- way 2 east of West Glacier. The project identified six reaches that must be mitigated and two more to be fixed if the con- tract funding is available. Traffic control is a major issue on this job since the road provides access to Glacier National Park. The project includes scaling, draped rockfall protec- tion, trim blasting, and other techniques as may be deter- mined by the design-builder. Rationale: MDT chose DB project delivery because it appeared to be the best method for sharing the risk of geotech- nical uncertainty. The preferred rockfall mitigation method was to scale the rock faces back to a safe angle of repose. However, there is no economical method for determining the angle, if there is one, by any other method than field trial. As a result, completing the design before setting the con- struction contract carried an unacceptable risk because of the high potential for DSC changes/claims. The project had a fixed budget of $3.0 million with no contingency. Therefore, MDT originally looked at using a fixed-price best-proposal BV award algorithm (Gransberg and Molenaar 2003). In this manner, the contract price would have been fixed at $3 mil- lion and each competing proposal would have stated how many of the eight reaches in the 14-mile zone it could do for that amount. Unfortunately, MDT’s enabling legislation requires it to use an adjusted score award algorithm, which requires the price be divided by the technical score with the lowest adjusted score becoming the BV (MDT 2011). The final alternative was to develop a unit price approach to those pay items that were expected to vary in quantities and bundle the remaining items into a single lump sum price. Procurement: The partial unit price method shown in Fig- ure 8 allowed the technical proposal to be scored and did not constrain the competitors to a stipulated price. The RFP used the following clause to articulate this approach: Bid Price Proposals will be submitted on the blank Bid Price Proposal Requirements Form included as an attachment to this RFP. The Bid Price Proposal form will include unit prices for the items indicated, a lump sum price for the remainder of the project scope and the completion date proposed by the Firm. The unit prices will include all costs associated with the construction of the items indicated. Each unit price will be multiplied by the quantity provided by MDT to determine the total amount for each of the unit price items. The Total Lump Sum for the project will be calculated by adding the extended sum of the unit price items with the lump sum amount for the remainder of the project scope. This total lump sum will be the final contract amount. The lump sum price will include costs for all design, surveying, geotechnical work, engineering services, Quality Management Plan, construction of the project (all items except the unit price items) and all other work necessary to fully and timely complete the project in accordance with the Contract Documents. The lump sum price will also include all job site and home office overhead and profit. It is understood payment of the lump sum amount for the project will be full, complete and final compensation for all work required to complete the project. If project [unit priced quantities] overruns or under runs occur at sites, the unit prices will be utilized to extend or reduce the work at other sites to maximize the amount of work accomplished for three million dollars (MDT 2011, italics added). FIGURE 8 Design-build bid price proposal form with unit price items. The clause makes it clear that MDT intends to spend the entire budget for this project and get as much work done as possible. This clause was followed by a second clause that describes what MDT will do if all price proposals exceed the budget: it will ask each responsive competitor to submit a “Best and Final Offer” that details the scope of work each competitor could complete for the specified budget. MDT would then repeat technical scoring and compute the BV based on the adjusted score. The RFP also explicitly encouraged including ATCs in the proposal. “Credit will be given for innovation in design and construction methods that minimize public impacts, mini- mize traffic delays, mitigate the risk of quantity overruns, and accelerate project delivery by reducing the total project

60 duration. Credit will also be given for design proposals that improve functionality and safety of the project” (MDT 2011). It contained a “Design and Construction Criteria Package (DCCP)” to furnish technical guidance to the design-builders during proposal preparation. The RFP described the ATC proposal process in the following manner: The Firm will identify separately all innovative aspects as such in the Technical Proposal and each must be explained in detail with any estimated cost increase or decrease. The Technical Proposal must state whether any cost increase or cost decrease resulting from innovation is included in the base Bid Price Proposal Amount. An innovative aspect does not include changes to specifications or established MDT policies and must conform to the RFP and DCCP requirements. Innovation should be limited to the Firm’s means and methods, approach to the project, rockfall mitigation techniques, use of new products and new uses for established products. Proposed changes to the RFP, DCCP, Design Concept, specifications or established MDT policies should be identified as Alternatives or Options in the Technical Proposal and explained in detail with any estimated cost increase or decrease to be considered together with innovative aspects, as the basis for scoring Technical Proposals. The estimated cost increase or cost decrease associated with any Alternative or Option that proposes changes to the RFP, DCCP, specifications or established MDT policies must not be included in the base Bid Price Proposal Amount (MDT 2011, italics added). The clause is an excellent example of a way for the owner to express its desires as well as its requirements. The phrase “an innovative aspect does not include changes to specifica- tions or established MDT policies” indicates that MDT spec- ifications and policies must be used. However, innovation is encouraged in “means and methods, approach to the project, rockfall mitigation techniques, use of new products and new uses for established products.” Quality Management: Table 35 shows the distribution of quality management responsibilities among parties to the contract. The table shows that MDT plans to stay actively involved in the QM process and share many of the design and construction QA tasks with the design-builder. This makes sense owing to the need to maximize the amount of work completed for the fixed budget. Joint responsibility also supports the issue that the final design will be function- ally reliant on trial and error data obtained in the field during actual scaling operations. It also supports the potential deci- sion to reduce the number of reaches mitigated if the quanti- ties overrun on early reaches by ensuring that the agency is actively engaged in verifying the actual angles of repose for the types of rock faces encountered in the field. Summary: MDT’s procurement approach on this project illustrates an alternative for sharing the risk of geotechni- cal uncertainty on a DB project. “Unit price contracts are used for work where it is not possible to calculate the exact quantity of materials that will be required” (Schexnayder and Mayo 2004). In a lump sum contract, the design-builder bears the entire quantity risk. Unit pricing for specific fea- tures of work inside a lump sum DB contract allows the agency to share the risk of the final quantities of work with the contractor and reduce the price. Requiring a lump sum price in a DB contract forces the contractor to bid the worst possible case for those items whose quantities cannot be accurately measured during proposal preparation (Grans- berg and Riemer 2009). Thus, it makes sense to use the DB contract payment provisions to manage geotechnical uncer- tainty through unit pricing. This case, plus the fact that three of the RFPs reviewed in the content analysis (two from Vir- ginia and one from Delaware) lead to identifying the use of selective unit pricing as an effective practice, also lead to a suggestion for future research to examine potential costs and benefits of employing selective unit pricing as a geotechnical risk management technique. TABLE 35 MONTANA DOT PROJECT QUALITY MANAGEMENT RESPONSIBILITIES Quality Assurance/ Quality Control Tasks Does Not Apply Agency Design- Builder Agency-Hired Consultant Technical review of construction shop drawings X X Technical review of construction material submittals X X Checking of pay quantities X X Routine construction inspection X X Quality control testing X Verification testing X X Acceptance testing X Independent assur- ance testing/ inspection X Approval of progress payments for con- struction progress X Approval of con- struction post-award QM/QA/QC plans X Report of noncon- forming work or punch list X X TH 61 Hastings Bridge Design-Build Project—Minnesota DOT (Mn/DOT) This project was included because of the difficult foundation conditions that had to be dealt with on the north approach to this bridge. The project involved replacing an existing bridge whose northern abutment had serious settlement issues

61 throughout its 30-year service life. It had been jacked back up into alignment three times. During the proposal prepara- tion period, Mn/DOT successfully employed the use of pre- approved elements (PAEs) that resulted from the analysis of ATCs proposed and discussed during confidential one-on- one meetings, which resulted in the winning design-builder proposing a column-supported embankment to address the extremely poor north approach subsurface conditions. Case 3—Minnesota DOT: TH 61 Hastings Bridge Design- Build Project, Hastings, Minnesota Value: $120 million Scope: Design and construction of a freestanding arch main span segment with low-maintenance, robust, and highly redundant concrete tie girders and knuckles. A main span is a 545-ft tied arch with freestanding, trapezoidal ver- tical steel arch ribs and post-tensioned concrete knuckles and tie girders. It is erected using a low float-in operation to maximize public safety. The south approach segment includes two side-by-side bridges that are five-span, solid cast-in-place post-tensioned concrete slabs with an arched soffit over Second Street and a constant 5-ft-deep cross section for the remainder of the spans. The north approach segment is a low-maintenance five-span precast concrete girder bridge. A north approach roadway is constructed on a column-supported embankment, with less than 2 in. of total settlement complete within 3 months of embankment con- struction. Project requires a 3-year warranty on settlement of the north approach and includes installed instrumentation for Mn/DOT to monitor settlement. Figure 9 is a rendering of the winning proposal’s design. Rationale: The highway commissioner directed Mn/DOT to accelerate the replacement of this particular bridge. There- fore, Mn/DOT selected DB as the most appropriate proj- ect delivery method to reduce the delivery period available within its statutory procurement constraints. The agency had recently completed the emergency replacement of the I-35W Bridge in Minneapolis and had an experienced project team in the same district. Additionally, Mn/DOT has successfully employed a sophisticated method to confidentially clarify RFP intent and evaluate/pre-approve ATC before award and believed that it could leverage these one-on-one confer- ences to not only encourage innovative solutions to the north FIGURE 9 Renderings of Hastings Bridge Design.

62 approach geotechnical problem but also to share the differing conditions risk with the winning design-builder. Procurement: The project used a typical two-step process with Mn/DOT first issuing an RFQ from which it developed a short list. The RFQ evaluated the qualifications and past experience of the geotechnical engineering team, assigning it 8% of the weight in the evaluation scheme. It then issued an RFP to the members of the short list. Geotechnical was assigned 5% of the total weight in the proposal’s technical evaluation. The literature confirms that a weight of 5% or more would be considered “heavily weighted” (Scott et al. 2006). The unique aspect of the procurement process that was particularly important to the geotechnical aspects of the project was the use of “private preproposal meetings” whose purpose was described as follows: Each Proposer is invited and encouraged to attend a private preproposal meeting at which the Department will address and respond to the Proposer’s concerns and questions regarding details of the project scope, administrative procedures, outstanding issues for the remainder of the bid process, and any other related matters. Each meeting would be private in that only one Proposer would meet with Mn/DOT representatives at a time. Proposers are not required to accept the meeting invitation (Mn/DOT 2010). The one-on-one meetings in this project generated between 6 and 13 ATCs from each competing design-builder. These resulted in as many as nine PAEs for one proposal, and the winning design-builder had eight that were incorpo- rated into its technical approach (Behnke and Ames 2010). Two of those, the column-supported embankment and con- tinuous settlement monitoring, were specifically related to innovative design solutions for the north approach geotech- nical problems. Figure 10 is a cross section of the column- supported embankment that illustrates the design-builder’s approach to this issue. Figure 11 is a detail of the continuous settlement monitoring instrumentation. FIGURE 11 Detail of the Hastings Bridge continuous settlement monitoring instrumentation (Behnke and Ames 2010). The effectiveness of the one-on-one meetings with the competing design-builders can be directly measured by the fact the project was awarded at a price that was $100 million FIGURE 10 Cross section of the Hastings Bridge column-supported embankment (Behnke and Ames 2010).

63 under the engineer’s estimate. The RFP stated that “price proposals that exceed $220 million will be considered non- responsive” (Mn/DOT 2010). Therefore, all the competitors had knowledge of the project’s budget. The adjusted score best-value award algorithm used in this project essentially makes the price equal to all other evaluation criteria by dividing it by the technical score (Scott et al. 2006). Thus, there would be some pressure on the competitors to keep their prices down. However, the success of the preproposal interaction between the agency and its proposers to clarify project risk and to furnish PAEs was ably demonstrated by the outcome of the proposal evaluation. The winning pro- posal was scored only 1 point in 100 lower than the best technical proposal while delivering the project for nearly 30% less cost. This leads to the conclusion that encourag- ing interactivity during DB proposal preparation for projects with significant geotechnical issues reduces risk and results in benefits to the agency. Quality Management: Table 36 shows the distribu- tion of quality management responsibilities among par- ties to the contract. It shows that Mn/DOT chose to retain much of the QA responsibility on this project. The Mn/ DOT response to the synthesis survey, which portrayed a broader perspective of Mn/DOT DB policy, assigned sole responsibility for routine inspection to the design-builder and indicated that a major role for an agency-hired over- sight consultant was absent in this particular project. This project also had a 3-year warranty for settlement. Warran- ties are often used in DB to relieve the agency of some QA responsibility (Byrd and Grant 1993). However, that was not the case in this project. One reason was that the design QM plans used on this project are different from those used on traditional design projects. The QM plans are project specific and quite complex regarding the geotechnical design. They require an internal audit and certification by the design-builder. Mn/DOT satisfied its due diligence duty by performing over-the-shoulder reviews throughout the geotechnical design. Summary: The project is under construction. This case study furnishes an example of the value of clarifying risk during proposal preparation rather than the traditional fielding of requests for information. That the competing design-builders had a contractual mechanism to approach Mn/DOT with possible design solutions to the thorny geo- technical issues associated with this project greatly reduced the risk that an innovative design would ultimately be dis- approved. Without the confidential one-on-one meetings and the PAEs, Mn/DOT would not have had the opportu- nity to consider technical solutions that its engineers and consultants had not contemplated. The extraordinary cost savings and the innovative solution to the north approach settlement problem validate the value of interactivity dur- ing DB proposal preparation, making this method an effec- tive practice candidate. TABLE 36 MINNESOTA DOT PROJECT QUALITY MANAGEMENT RESPONSIBILITIES Quality Assurance/ Quality Control Tasks Does Not Apply Agency Design- Builder Agency-Hired Consultant Technical review of construction shop drawings X X Technical review of construction material submittals X Checking of pay quantities X Routine construction inspection X X Quality control testing X Verification testing X Acceptance testing X Independent assur- ance testing/ inspection X Approval of progress payments for con- struction progress X Approval of con- struction post-award QM/QA/QC plans X Report of noncon- forming work or punch list X X I-270 Slide Repair Project—Missouri DOT This project was selected for inclusion because it illustrates an innovative approach to including a DB provision inside of a DBB contract. Additionally, the case was successful in that it generated an innovative geotechnical design that permit- ted construction without lane closures on an urban freeway (McLain and Shane 2009). The case is an emergency repair and stabilization project that resulted from a landslide that damaged a triple box culvert and threatened to close the east- bound lanes of I-270 in St. Louis County, Missouri. Case 4—Missouri DOT: I-270 Slide Repair Project, St, Louis County Value: $552,148 Scope: Design and construction of temporary shoring needed to protect the interstate traffic as well to allow quick repair of the box culvert after a landslide (see Figure 12). The temporary shoring also allowed the slope to be restored with shot rock. The project ultimately designed and built a temporary soil nail wall that had more than 150, 40-ft nails spaced at 5 ft horizontal and 5 ft vertical and was 45 ft high.

64 The design-builder originated this innovative solution to replace MoDOT’s conventional slide plane removal and replace technique (McLain 2008). FIGURE 12 I-270 slide aftermath. Rationale: MoDOT awarded a DBB project on a con- ventional project in this location that contained a “nested” DB provision for repair of slides during construction by a prequalified geotechnical specialty subcontractor as required during the contract period. The primary rationale for selecting this form of DB to shorten the time the roadway is out of commission and to encourage innovative methods to lessen the cost of the slope repair projects. Procurement: The typical MoDOT process to award a low-bid project includes a 10- to 14-week design review period before a construction contract can be advertised if the project costs more than $1.0 million. Added to this is another 3-week period to award the construction contract. By adding the “nested DB provision” for landslide repairs inside the DBB contract, MoDOT avoided the delays inher- ent in developing a new project or the issues of getting waiv- ers to react to an emergency requirement. The nested DB provision required the prime contractor to subcontract this work with a prequalified geotechnical specialty contractor that had experience successfully completing MoDOT slide repair and other types of projects. Quality Management: Table 37 shows the distribution of quality management responsibilities among parties to the contract. Since this DB project was constructed inside a larger DBB contract, one would expect MoDOT to approach QA in the same manner that it uses for DBB projects. How- ever, it did assign the design-builder the responsibility for QC testing. Summary: The project was completed 120 days after the slide damage occurred. The design took 5 days. These peri- ods compare to an average of 205 days from slide to con- struction completion and 50 days for design for two similar projects that were procured using DBB (McLain and Shane 2009). The use of the soil nail wall permitted the construc- tion to be completed without closing any lanes on I-270. In a conventional slide plane removal and replacement method, MoDOT would have needed to close at least one lane of traf- fic throughout construction. TABLE 37 MISSOURI DOT PROJECT QUALITY MANAGEMENT RESPONSIBILITIES Quality Assurance/ Quality Control Tasks Does Not Apply Agency Design- Builder Agency-Hired Consultant Technical review of construction shop drawings X Technical review of construction material submittals X Checking of pay quantities X Routine construction inspection X Quality control testing X Verification testing X Acceptance testing X Independent assur- ance testing/ inspection X Approval of progress payments for con- struction progress X Approval of con- struction post-award QM/QA/QC plans X Report of noncon- forming work or punch list X CONCLUSIONS The analyses discussed in this chapter resulted in the follow- ing conclusions: • The use of a GBR as a means to allocate subsurface condition risk appeared to result in savings on the O’ahu Elevated Guideway project. • Mn/DOT’s interactivity with competing design-build- ers during DB proposal preparation through the RFP clause that initiated confidential one-on-one meetings and resulted in PAE reduced risk to the design-builders and resulted in significant benefits to the agency on the Hastings Bridge project.

65 • DB project delivery permitted MoDOT to complete an emergency slide repair on the I-275 project in significantly less time than two previous DBB slide repair projects. This chapter also identified the following effective practices: • The use of a “nested” DB provision that required a prequalified geotechnical specialty subcontractor to be a member of DBB general contractor’s team on a project with known geotechnical issues provided a mechanism to expeditiously resolve a landslide. This technique not only saved time but also brought an innovative tempo- rary soil nail wall solution that permitted the slope to be stabilized without lane closure on an urban freeway. • The use of selective unit pricing as done by the Montana, Delaware, and Virginia DOTs provides an effective means for managing geotechnical quantity risk. • Permitting some form of confidential discussion and clarification of geotechnical risk during DB proposal preparation through a process such as the Mn/DOT one-on-one meetings assists competing design-build- ers in making design assumptions that can be priced without including large contingencies. • The ability to assess design-builder ATCs before pro- posal submission and the use of PAEs encourages inno- vative design solutions to difficult geotechnical design problems, such as the north approach settlement prob- lem in the Hastings Bridge project. The confidentiality of the process is key to its success. The following suggestions for future research are made: • Guidance is needed about effectively managing geo- technical cost, time, and technical risk in DB projects. The research will include the following: – Examination of potential costs and benefits of employing selective unit pricing as a geotechnical risk management technique. – Use of specialty geotechnical DB subcontracts in DBB prime contracts, such as MoDOT’s. – When to employ GBRs in DB projects. • Since a number of state DOTs use some form of inter- activity during DB proposal preparation, research is needed to quantify the costs and benefits of instituting a program such as Mn/DOT’s PAE process and to fur- nish guidance to agencies that do not allow interaction in their DB programs. The research would also explore legal barriers to implementation as well as case studies of any litigation or protests that resulted from the use of this approach.