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20 This chapter describes a rough process by which sustainability can be used as a criterion for evaluating any proposed construction practice. This is beneficial because: 1. The evaluation process can endure as a useful tool as industry practices change. As the highway construction industry evolves, the SCPs identified in this guidebook may become part of regulations and standard practice; or they may become obsolete. This evaluation process can be used with future construction practices to determine their rough impact on sustainability. 2. Contractors and owners can use the evaluation process to propose and judge highway construction practices that meet sustainability objectives for a project. A standard evalu- ation process helps all parties understand how proposals are evaluated and allows (1) owners to be consistent in their evaluation of sustainability beyond the listed SCPs in this guide- book and (2) contractors to better tailor their efforts to stated owner priorities. The evaluation process described in this chapter asks evaluators to consider the sustainability framework provided in this guidebook and judge the impact of a proposed construction practice on each sustainability category in relation to the standard practice or regulatory requirement. Impacts are judged from the perspective of the entire construction project, and not just one party (not just the owner or just the contractor). Evaluators may choose to customize the process to best match stated project priorities. 4.1 Evaluation Process Determine the impact of a proposed highway construction practice on each of the 10 sustain- ability categories. Impacts are considered relative to standard practice or regulatory require- ment and should be determined both for the construction process and for the life of the facility thereafter. Generally, impacts over the life of the facility (which can be 20 to 100 years or more) are greater than those that occur during construction (which can be several years, at most), so life-of-the-facility impacts are counted as twice the construction impacts. In most cases, it is sufficient to quantify these impacts as present or not; however, impacts can be considered significant and given extra weight, but only if quantified. Table 5 shows the basic impact values and criteria. If the total sum of impacts is positive, then strong consideration should be given to accepting the proposed construction practices as a sustainable alternative to the baseline. Table 6 presents the sustainability evaluation process as a table. To use Table 6, fill in each cell where an impact is identified with values from Table 5. Other cells remain blank. Sum up the impact values for each impact category (construction impacts only, and life-of-the-facility impacts) and enter the total in the sum cell for each. Then, multiply the sum for each by their C H A P T E R 4 Using Sustainability as a Criterion to Evaluate Highway Construction Practices
Using Sustainability as a Criterion to Evaluate Highway Construction Practices 21 respective multiplier (1 for construction, 2 for life of the facility) and enter the result in the subtotal cell for each. Add the subtotal cells and enter the result in the total cell. If the total cell is positive, then strong consideration should be given to accepting the proposed construction practice as a sustainable alternative to the baseline. Value Criteria +1 Positive impact that is unquantified or quantified and small (< 1% of contract value) +2 Positive impact that is quantified and significant (⥠1% of contract value) â1 Negative impact that is unquantified or quantified and small (< 1% of contract value) â 2 Negative impact that is quantified and significant (⥠1% of contract value) Table 5. Impact values and criteria. Dimension Category C on st ru ct io n Im pa ct s O nl y L if e- of -t he - F ac ili ty Im pa ct s Human Well-being Workers Neighbors and Stakeholders Users Environmental Well-being Pollution Local Ecosystems and Habitat Consumption Climate Economic Well-being Project Budget Maintenance and Operations Economic Development/Employment SUM MULTIPLIER x 1 x 2 SUBTOTAL TOTAL Table 6. Default evaluation table. 4.2 Customizing the Evaluation Process If needed, the process in Section 4.1 can be customized in the following ways (Table 7): 1. Each sustainability category can be weighted. It may be that for some projects it is useful to weight sustainability categories, which effectively makes some categories more important than others. This can be done to prioritize certain categories based on sustainability objectives. If so, the values entered in the empty cells should be multiplied by the weighting factor first. For instance, if the selected impact is +2 and the weight factor is selected as 2, then the value entered in the cell is +2 à 2 = 4. 2. The multipliers for construction only and life of the facility can be changed. The multi- pliers of 1 for construction only and 2 for life of the facility should suffice for most projects. However, if there is good reason, they can be adjusted. 3. Instead of values from Table 5, actual quantifications can be entered in the blank cells. If the effort is made to quantify impacts and if those quantifications are all in the same units (e.g., dollars or MTCO2e), the quantifications may be substituted for the values in Table 5 in the evaluation table.
22 Sustainable Highway Construction Guidebook Customization should be done with care and purpose. Impacts on the evaluation process should be clearly understood and customization should be done with good reason. For instance, customization may be suitable for a project that clearly values certain sustainability categories or for a project that has a long or sensitive construction process or an anticipated short life. In most cases, using the default values will lead to the same conclusions and customization is not necessary. Dimension Category W ei gh t F ac to r C on st ru ct io n Im pa ct s O nl y L if e- of -t he - F ac ili ty Im pa ct s Human Well-being Workers ? Neighbors and Stakeholders ? Users ? Environmental Well-being Pollution ? Local Ecosystems and Habitat ? Consumption ? Climate ? Economic Well-being Project Budget ? Maintenance and Operations ? Economic Development/Employment ? SUM MULTIPLIER x? x? SUBTOTAL TOTAL Table 7. Customized evaluation table.
