• Expected transportation distances for all materials. This means distances from source to production as well as from production to site. Transportation of waste to disposal is also included.

• Expected construction vehicle types. These include, but are not limited to, pavers, mixers, hauling vehicles, excavators, rollers and finishing equipment. Obviously use of the new mobile equipment meeting Tier 4-interim emissions guidelines would be a plus.

• Estimated design life. This should reflect the same input data as used in Greenroads Lifecycle Cost Analysis section.

• Scheduled years and expected type of maintenance. Likewise, Greenroads suggests use of the same input data as used in its Lifecycle Cost Analysis, and meet project specs provided for its pavement and site maintenance plans.

FHWA’s INVEST Now a Reality

On October 10, the Federal Highway Administration’s INVEST sustainable pavements rating system was introduced. Not a calculator per se, it’s a totally free, voluntary, web-based tool for assessing the environmental sustainability over the lifecycle of a transportation project or program, including system and project planning, through design and construction, to operations and maintenance.

Opening screens of detailed National Ready Mixed Concrete Carbon Calculator, a spreadsheet that enables calculations of carbon footprint of concrete products and projects.

INVEST is intended to permit agencies to assess their own transportation plans, projects and programs, and help them make more informed decisions with limited resources to balance what FHWA calls economic, social and environmental factors.

Goals of INVEST are to support the U.S. DOT’s aims for livability and sustainable transportation, increase the body of knowledge regarding sustainability aspects of both asphalt and concrete materials in pavement design, construction, preservation and maintenance, and to boost use of sustainable technologies and practices in pavement design, construction, preservation and maintenance, FHWA says.

More information – and the program – may be downloaded at www.sustainablehighways.org

NAPA’s Greenhouse Gas Calculator

The National Asphalt Pavement Association has stepped into the fray with its Greenhouse Gas Calculator for pavements, revised in 2012 and currently under beta testing.

This online tool calculates greenhouse gas emissions related to asphalt pavement manufacturing in a gate-to-gate analysis. “The user-friendly interface provides drop-down lists of typical fuels that are linked to greenhouse gas emission factors, expressed as carbon dioxide equivalents (CO2e), the universal measure of greenhouse gas emissions,” NAPA says.

The calculator provides inputs for three separate fuels used by a rotary dryer, plus three additional fuels used inside the facility by equipment, including vehicles. “A final category addresses CO2e attributed to electrical use, with unique factors for each state,” NAPA says. “Fuel used for onsite power generation should also be included. Generally, the more fuel combusted or burned, the more CO2-equivalent gases [that] are emitted.”