Data Collection Protocol

• The construction process being modeled and the level of granularity for process modeling, e.g., model at the level of "paving" or at the level of "earthwork", "grading", "asphalt paver", "concrete paver" etc., that are inputs to the process "paving".

• The reference unit for the process being modeled. Use the same units of work as your state construction specification uses for the pay-item most closely associated with the process, e.g., if you are modeling "concrete paving", the unit may be per square yard, or per lane mile. 

• Background life cycle inventories: Ways to work with Repositories and Inventories in Learning Modules (Under Construction).

  • Use the EPA equipment inventories in the FHWA Repository - reported in MJ

  • For materials use product and facility specific EPDs whenever they are available

  • When EPDs are not available use the asphalt and concrete LCI in the FHWA Repository, and if possible, and customize the inventory with the following data:

    • Ask agency/contractor for the mix design information 

    • Ask contractor/producer for production specific parameters

  • When EPDs are not available, and the agency, contractors/producers are not forthcoming with parameter data, then use the default parameters in the materials inventories.

For a given construction operaiton:

• List the equipment associated with selected operation (pavers, excavators, graders)

  • Type and quantity of fuel used (diesel, volume in m3 or gal)

  • Horsepower and other equipment specs including dimensions 

  • Fuel consumption for each equipment (gal/hr, or m3/hr)

  • Project specific: work completed per unit of energy used (units of work done/gal)

  • Identify the bill of materials from the bid tabs - this may be total quantity for the project

  • Haul distances for materials to site and the typical capacity of hauling trucks. 

Operation specific modeling is preferred, though at times, project specific may be appropriate

• Convert the collected data to parameters 

  • Diesel used in equipment is typically reported in gallons - unit used in equipment inventories is in MJ. Suggested conversion factors for diesel:  

    • Density: 867.3026 kg/m3

    • Energy: 42.91 MJ/kg

    • Unit conversion: 264.172 gal/m3

• Model estimation parameters where relevant:

  • Quantity: Estimate quantities of material used per reference unit. This can be done in two ways:

    • Project specific: use the total quantity from the bid tabs, and pavement design information to estimate a tons/lane-mile estimate.

    • Construction Operation Specific: the emphasis here is the consumption of material as an input flow to an equipment as a function of the reference unit of work completed. For example, for asphalt paving, if the reference unit is 1 lane-mile, and a 2" asphalt mat is being paved then estimate the quantity of asphalt as a material input flow in ton/lane-mile paved, given a density of 113 lb/sq-yd/in, and the conversion factor of 7040 sq yd/lane-mile. 

  • Time: When estimating construction operation specific parameters that are expressed per unit of work completed, sometimes time parameters need to be estimated. 

    • For example, the production rate of a paving operation will dictate the number of truck loads required to complete a reference unit of work. The number of truck loads, the haul distance and the truck loads will support the parameter informing the ton-miles of truck transportation.

    • Check that production parameters estimated based on time are consistent with the production rate from production plants.

Inventories:

• Develop OpenLCA inventories using the collected data to report for items such as, but not limited to:

  • Asphalt paving operation, kg of CO2 e., per lane-mile or per sq. yd

  • Concrete paving operation, kg of CO2 e. per lane-mile or per sq. yd

  • Earthwork operation, kg of CO2 e. per cyd

  • Grading operation, kg of CO2 e. per lane-mile or per sq. yd

• For each inventory report equipment type (model and make), parameters modeled with references used, assumptions made (e.g., fuel consumption rates), material design information, and EPD sources when relevant.

• Report midpoint indicators using TRACI 2.1 impact assessment method.

• Report inventories in OpenLCA format ensuring that all permissions have been granted for public use as necessary.

Research Products:

• Any analysis pertaining to the data collected that has been been peer reviewed (journal publication, conference presentation, third party reviewed conforming to ISO 14040/44).