Sustainable roadway construction data from Greenroads certified projects
Data was collected as part of the roadway construction certification offered by Greenroads International according to Greenroads Rating System v1.5. This dataset is the result of data collection efforts for 33 construction projects across the US and abroad. Data was initially collected by Greenroads International as part of its certification process and was later obtained by this dataset's contributors. Projects in pursuit of certification submit supporting documents as evidence for performing a roadway construction practice. For example, tracking the amount of water used in construction to earn points and satisfy a credit in Greenroads. We hypothesize this dataset is unique in that it contains information and statistics on roadway construction projects that are declared sustainable with numeric outcomes to act as performance benchmarks for future projects to follow. Construction documents were first used to collect data on 12 sustainable performance benchmarks explained in the dataset (see Performance Benchmarks and Project Properties and Landscape Plans files). Sustainable performance benchmarks are established using median values of quantitatively measurable project outcomes. These benchmarks are defined in such a way that any roadway construction project regardless of size or scope may use them as sustainability achievement goals. In that, these performance benchmarks are somehow normalized to an aspect of the project’s size such as its monetary value, length, or area. Except for the source documents used to produce sustainable performance benchmarks, the dataset contains numeric values obtained from digesting several digitally formatted documents or spreadsheets submitted by project teams. The other major construction document included in this dataset is the pay item list from 30 projects (three projects did not provide this data). Pay item lists contain all the items used in the bidding process of a project and include a short description of each item, a unit of measure, the unit price, and the total price (see Pay Item Lists for LCA and Construction Materials LCA files). Several other construction documents were used to reinforce projects’ pay item lists with enough information for environmental impact assessment. As a result, many other data attributes were added to the pay item list data for each project. These include but are not limited to material’s unit weights, breakdown of material constituents (e.g., how much cement is in a concrete item), transportation distances, etc. Finally, life cycle inventory (LCI) data for the primary construction materials (see Materials LCI file) were collected from publicly available sources and were embedded into the pay item list data for life cycle assessment of materials used to build roadways. We analyzed the resultant dataset to estimate the greenhouse gas emissions and energy consumption of projects. When necessary, each dataset contains a metadata worksheet that explains data attributes.
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The majority of data was collected from construction documents. Some of the data are the result of entires from project teams in the Greenroads web platform. That includes some general properties of the roadway like its length, budget, year of construction, contracting method, the main motivation of the construction, the type of roadway under construction, etc. We call these project portfolios. Once projects register for Greenroads certification, they indicate which credits they are about to pursue based on their scope of work. Projects are then required to submit supporting documents showing evidence of the activities needed to obtain scores and finally certification. The Greenroads data repository collects documents and files into several folders with a prefix in the file name denoting the Greenroads category the data was submitted for. This way, Greenroads acts as a data collection and management tool beyond its main purpose of granting certification to sustainable roadway projects. The performance benchmarks established in this dataset and its subsequent analysis are those that most projects provided data for. Our goal was to include only quantitative measures of sustainability that at least 1/3 of projects provided some sort of information/documents for. The result was a selection of 12 performance benchmarks and we took extra effort to extract numbers from several construction documents such as pavement design, stormwater management plans, drawings, etc. In some cases, Greenroads asks for a specific type of document or activity that was beyond what a project required per its stakeholder request; a good example can be tracking the recycled content in construction materials. Future projects can use the same definition of benchmarks and their numeric representations to track their sustainability efforts and compare them to those established here. The other major data source (typically in a spreadsheet format) is the pay item list. Pay item lists (also known as bid tabulations) are mainly used in design-bid-build projects that need to provide a list of all items that are going to be placed to deliver a project, in addition to the price of materials and construction activities for each item (so the name 'pay item list'). Although pay item lists are mostly used for the bidding process and procurement of construction projects, as this dataset shows, they can act as an environmental impact accounting tool. The pay item list data here is further reinforced with several other pieces to describe each pay item (e.g., material types and applications, estimated weight, and proportion of materials). This dataset uses life cycle inventory (LCI) data collected from publicly available sources to perform life cycle assessment (LCA). This dataset indicates what extra attributes can be added to a pay item list. This dataset also serves as a reference for LCA practitioners. Especially, the LCA data can be updated using more recent inventories in the future.