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Greenhouse Gas Emission Mitigation in Road Construction and Rehabilitation: A Toolkit for Developing Countries

Available for Download Now!

See below for links to the final report, Greenhouse Gas Emission Mitigation for Road Construction and Rehabilitation: A Toolkit for Developing Countries, and the ROADEO Calculator and User Manual.




Vietnam road constructionAddressing global climate change is a paramount challenge of the 21st century. According to the Intergovernmental Panel on Climate Change (IPCC), warming of the earth’s climate is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level [Intergovernmental Panel on Climate Change (IPCC), 2007, 1st Working Group, 4th Report].

Since the beginning of the Industrial Revolution (approximately 1750), atmospheric concentrations of carbon dioxide (CO2), the chief heat-trapping greenhouse gas (GHG) have risen 35 percent, from about 280 to 377 parts per million (ppm). This increase is primarily from the burning of fossil fuels and from deforestation. Carbon dioxide is the single most important GHG on a multi sectoral level, accounting for more than 75 percent of annual emissions in terms of CO2-equivalents and is the primary contributor of the transport sector [Intergovernmental Panel on Climate Change (IPCC), 2007, 1st Working Group, 4th Report].

The transport sector accounts for nearly 14 percent of global GHG emissions according to a 2009 World Resources Institute study [World Resources Institute (WRI), 2009, Climate Analysis Indicators Tool (CAIT)] of which approximately 72 percent is attributed to road construction, rehabilitation, maintenance, service, and usage.

Indonesia road constructionGlobally, Asia is responsible for approximately 37 percent of total GHG emissions, with China accountable for nearly 19 percent of the world’s total or over 50 percent of Asia’s contribution. Although the contribution of the transport sector to GHG emissions in Asia is relatively small (about eight percent) compared to transport sectors in other regions (approximately one-half of Europe and one-third of North America), the potential GHG emissions growth is enormous as Asia is home to over fifty percent of the world’s population.

As transitional economies and populations continue to grow, it is anticipated that over the coming several years, developing countries in East Asia will be substantially expanding and restoring their extensive highway networks. One consequence of these activities is GHG emissions attributable to the transport sector will continue to grow towards those recorded in Europe and North America.

The East Asia Sustainable Development Infrastructure Unit at the World Bank conducted a study on the mitigation of GHG emissions due to road construction and rehabilitation in East Asia. The aim was to identify and quantify the GHG emissions from current practices and develop a strategy for the better planning, design and construction of roads to minimize these emissions. The outcome of the study is a GHG Toolkit that consists of: (i) ROADEO (Road Emissions Optimization), software for calculating GHG emissions at the planning, design, and construction phases, (ii) a calculator user manual, and (iii) a report on GHG emissions generated by road construction and rehabilitation activities, which is classified by work categories and includes analysis of local and international best practices.

road construction

The GHG emissions calculator was designed for road planners, designers, and construction managers with previous expertise in road construction and rehabilitation. Practitioners can apply this tool to optimize the process at each given phase for economic mitigation of GHG emissions. This initiative represents an effort to introduce new methodologies to reduce the gap between international best practices and the state-of-practice of road construction and rehabilitation in East Asia. The development of the GHG Toolkit involved the selection of China, Indonesia, and Vietnam as pilot countries. 

china roadAlthough designed to be used at all phases, the calculator is innovative in that it can be used at upstream stages with minimal inputs. By the construction phase, the user has the opportunity to enter over 400 input variables that can impact the project’s carbon footprint or to use default values based on a comprehensive review of the state-of-practice of road construction and rehabilitation activities in East Asia. The database of emissions factors consists of three main categories including materials, equipment, and transport (drawn from internationally verifiable sources). The tool’s boundaries are from the aggregate quarry, cement manufacturing plant, bitumen refinery, and steel plant to the implementation of the road works including all intermittent activities (the tool does not consider the quarrying of the raw materials that are used to manufacture cement, the extraction of oil for bitumen, etc.).  Outputs are divided into material, equipment, transport, and total as well as subdivided into earthworks, pavement, drainage, structures, and road furniture for easier identification of where GHG emissions mitigation can be pursued.

Project Overview

Toolkit Objectives

Primary Objective
  • Evaluate GHG emissions of a road construction or rehabilitation project at various phases (i.e., planning, design, and construction/rehabilitation)
  • Expose developing countries to international best practices and alternative techniques that can help reduce GHG emissions
  • Raise awareness of GHG emission issues within road agencies and other stakeholders
Secondary Objective

Use the calculator as a means to monitor and evaluate World Bank safeguards requirements and national environmental guidelines as well as international best practices.

Target Users

  • Planners: Compare the GHG emissions of potential layouts that may require bridges or tunnels, increase travel distances to avoid natural boundaries, or necessitate large volumes of cut or fill
  • Designers: Assist with evaluating horizontal and vertical alignments, pavement thicknesses and materials, as well as structure types and materials based on carbon footprint and economic feasibility
  • Construction Managers: Evaluate site layout, fill material options, equipment selection, and base or embankment stabilization techniques amongst many factors that can influence the GHG emissions of a roadway project

Tasks Completed to Create Toolkit

  • Task 1: Broad assessment of GHG emissions related to transport sector
  • Task 2: Detailed literature review on GHG emissions from road activities
  • Task 3: Road construction and rehabilitation practices in 3 East Asian developing countries
  • Task 4: Case studies selection and detailed analysis of GHG emissions
  • Task 5: Perform GHG emission calculations
  • Task 6: Identify gaps between international best practices and state of the practice as well as proposals for improving the situation
  • Task 7: Assess costs and benefits of each alternative practice proposed in Task 7: Assess costs and benefits of each alternative practice proposed in Task 6
  • Task 8: Develop the Greenhouse Gas Emission Mitigation Toolkit for Road Construction and Rehabilitation
  • Task 9: Complete the User Manual to accompany the Toolkit

Overview of the ROADEO Calculator

Calculator Methodology—Architecture

Architecture chart














Calculator Methodology—Toolkit Boundaries

toolkit chart
















Calculator Methodology—Algorithms

  • Data/calculations come from:
    • Built-In Values
    • Suggested Values
    • User-Defined Values
  • The method of calculation is derived from four main components of algorithms: emissions generated from materials, transport, and equipment
  • The emission factors are drawn from internationally verifiable sources, including the Inventory of Carbon and Energy, the French Environmental Agency Ademe, various construction equipment producers, and the World Resources Institute
  • Materials, equipment types, transport modes, and emission factors can be added and updated by the user
  • Calculation consists of one predefined table for each GHG generator (materials, equipment, and transport ) with multiple variables, including:
    • Works Component: User specified characteristics and quantities or default values based on typical designs or works in East Asia; Customized based on project requirements
    • Characteristics: Variables providing basic characteristics about each GHG generator (material physical composition, equipment type, transport mode, origin, destination, etc.)
    • Quantifying Data: Measurement values of each GHG generator (volume, weight, capacity, distance, fuel/electricity type/consumption, etc.)
    • Emission Factors: Kilograms of CO2 equivalents from verified source


  • Length of existing cross-drainage as a percentage of requirement
  • Length of existing longitudinal drainage as a percentage of length of road
  • Parameter reflecting the balance between cut and fill
  • General longitudinal profile
  • Length of road in mountainous terrain as a percentage of road length
  • Volume of rocky soil as a percentage of volume of soil
  • Length of the road project crossing urban areas as a percentage of road length
  • Volume of embankment treatment
  • Number of bridges to be widened as a percentage of number of bridges
  • California Bearing Ratio
  • Equivalent standard axle (8.2t) loading – ESAL
  • Existing cross-section
  • Road project length
  • Lane width
  • Median width
  • Median type
  • Number of lanes
  • Overlay structure type
  • Pavement structure type
  • Road type
  • Area where subgrade has to be treated with hydraulic binders
  • Shoulder width
  • Shoulder type
  • Type of barrier material
  • Type of structure (standard bridges)
  • Type of structure (major bridges)
  • Type of structure (wall)
  • Length of tunnel
  • Works type

With these inputs and a theoretical bill of quantities, a user is able to estimate the GHG emissions from a project. With an actual bill of quantities and site specific information that would be available during the construction phase, a user is able to more accurately determine the GHG emissions.


  • Earthworks, pavement layers, structures, roadside furniture, and drainage
  • Subdivided by materials, equipment, and transport
  • Current or total project GHG emissions
  • By percentage of category and in total tons of CO2 equivalents

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