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Defining the LCA Study

In defining how an LCA study will be carried out, certain parameters must be addressed as well as how data and data quality requirements are handled. The starting point for any discussion on topics such as LCA goal and scope definition as well data and data quality requirements, are LCA standards such as ISO 14044 and EN15804. This guide goes a step further and narrows the room for interpretation found in standards, addressing topics that are specific to road and rail infrastructure and taking into account the developed PCRs for both road and rail (CPC 53210, 53211 and 53212).

4.1 Purpose of the Assessment - Goal and Scope Definition

4.1.1 Defining the Goal

An LCA can provide support for decision making across all stages of the planning process as well as the development of a climate declaration for a completed project. The specific goal at each planning stage will vary to reflect the type of decision being taken. During feasibility studies and early planning, the goal will relate to providing decision support in selecting infrastructure solutions, e.g. selecting a specific corridor. During the later planning stages and construction, the goal will be to identify solutions for elements, components and materials with the lowest environmental impact.

It should be noted that all assessments will have a large degree of uncertainty due to these activities linked to operation and maintenance taking place in the future and the assumptions that will have to be made. It is therefore critical not to assume that increased emissions occurring during construction will be compensated during operation and maintenance, as there is a very high level of uncertainty.

The intended audience will include decision makers and consultants that deliver the design as well as stakeholders such as public authorities.

4.1.2 Defining the Scope

Product system definition

Product systems in order of complexity are defined as:

  1. ​​Transportation system (e.g. combination of transportation solutions)
  2. Project (e.g. road/rail from point A to point B)
  3. Element (e.g. stretch of road, bridge, tunnel)
  4. Component (e.g. pavement overlay, railway sleepers)
  5. Material (e.g. asphalt type)

Functional unit

The functional unit of the LCA shall follow the principles defined under ISO 14044 and will depend on the types of decisions being made. When reporting overall emissions of road/rail infrastructure at a national level, a representative functional unit is to be chosen that may differ from what is suggested below.

For feasibility studies and early planning the functional unit is to be defined as:

  •  One complete project in operation over the sudy assessment period. The result is to be presented as a total as well as individualy for all life cycle stages of the project.​ 

For later planing stages and construction the functional unit will vary for road and rail infrastructure and is to be defined as:

  • Road infrastructure: one km of road. The road’s overall environmental impact and the environmental impact per km shall be reported together  with the total amount of Annual Average Daily Traffic (AADT), speed limit, dimensions and number of lanes. The option to define the functional unit as one m2 of road may also be considered when supported by the study goal and the product system definition. 
  • Rail infrastructure: one km of railway (km of railway with a given function and number of tracks). The railway’s overall environmental impact and the environmental impact per km shall be reported together with type of vehicle operation (e.g, high speed, metro, etc.).

(Note that the PCR defines the functional unit of one m2 of road, while this guide defines the functional unit as one km of road. It is expected that in the coming revision of the PCR, the functional unit will change to one km of road, as is defined in this guide.)

It should be noted that there are many expected differences between road/rail through tunnel or bridge and the details of each stretch should be described and presented together with the functional unit.

When defining the functional unit, it is common practice to identify the actual function of the product or system. In the case of road and rail infrastructure, this is the transportation of passengers or freight. It was briefly considered that the functional unit defined should address the actual function of the infrastructure. However, the impact on the results of assumptions made on passenger load is too big and too uncertain. 

System boundaries

The system boundarie should follow EN 15804:2019 and EN 15978:2011. Any changes of the system boundaries should be stated in LCA reports to ensure transparency when communicating results. In this guide, activities are addressed under each planning stage that require specific consideration. 

Reference Service Life (RSL) and study assessment period

The RSL is the service life of rail/road infrastructure which can be expected under normal operating conditions. An RSL of 60 years is suggested. However, a longer or shorter RSL may be defined when supported by the study goal and product system definition. Elements or components might have a specific RSL that will often be lower than 60 years. When assessing then environemntal impact at element or component level, it is recommended to use the estimated service life of each element or component, as provided by the supplier.

4.2 Data Quality

Data quality requirements set in this guide vary with the applicable planning process stage of the LCA (see chapter data quality sections in chapter 5). The requirements are less stringent during early planning while they increase significantly during the later planning stages and construction.

Further work on standardization of emission factors, system boundaries and even RSL for elements and components would allow for higher data quality and comparability of results. The example of Norway where a number of LCA tools have aligned their methodology should be viewed as a possible way forward at a national level, which could then be implemented in the Nordics as a subsequent step.

4.3 Life Cycle Impact Assessment

The environmental impact categories assessed in an LCA following this guide shall include Global Warming Potential (GWP 100), defined as GWPFOSSIL according to EN 15804:2019.

In addition, it is recommended that GWP from land use and land use change (GWPLULUC) is reported, while reporting GWPBIOGENIC and GWPTOT is optional.

​GWPFOSSIL Mandatory​
​GWPLULUC ​Recommended

When applicable, results should be reported separately for GWPFOSSIL, GWPLULUC, GWPBIOGENIC and GWPTOT.


Though this guide focuses on greenhouse gas emissions, for an extensive overview of the environmental impact of the rail/road infrastructure project, it is recommended that the environmental impact categories assessed are not limited to GWP and instead include all core environmental impact indicators specified in EN 15804:2019.

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