BAR methodology

A Methodology for Post-Disaster Building Assessment

The BAR methodology was published in March 2016 by researchers from the Signal Program on Human Security and Technology at the Harvard Humanitarian Initiative (HHI). The article can be read here. BAR stands for the three authors of the methodology: “Baker, Achkar, Raymond”. With the aim of facilitating humanitarian interventions in the field and complementing ground-based assessments, this guide proposes a standardized methodology for rapid, reproducible disaster damage assessment. This approach analyzes geospatial data, such as satellite or drone imagery, and can therefore be remotely mobilized by online volunteers and integrated into OpenStreetMap. The following section is taken from the Guide, page 9:

The Signal Program BAR Methodology applies a color-coded damage scale across all structure types based on repeating, visible damage patterns. Damage in the BAR scale is classified in 4 distinct categories: Green, Yellow, Orange and Red.

* No Visible Damage: This category, classified by the color green, signifies no visible damage to the structures. In these cases, the roof is virtually undamaged and the walls, in effect, remain standing. The structure appears to have complete structural integrity and does not appear to need repair.

* Minimal Visible Damage: This category, classified by the color yellow, signifies that some minimal visible damage has been sustained. In these structures, the roof remains largely intact, but presents partial damage to the roof’s surface, with minimal exposure beneath. In oblique aerial and satellite imagery, minimal damage may be able to be observed within the structure and to the exterior walls. The structure appears to have general structural integrity but needs minor repairs.

* Significant Visible Damage: This category, classified by the color orange, signifies that partial but ex-tensive visible damage has been sustained. In these structures, the roof is entirely damaged or missing. The walls of the structure remain upright. However, the interior wall partitions can be partially damaged. Debris inside the structure can also potentially be visible. The structure does not appear to have complete structural integrity and is in need of significant repair.

* Critical Visible Damage: This category, classified by the color red, signifies severe visible damage has been sustained. In these structures, the roof is completely destroyed or missing, and the walls have been destroyed or collapsed. The support structures are completely leveled, and interior objects have also suffered visibly heavy damage or destruction. The structure does not appear to have any structural integrity and requires comprehensive reconstruction or demolition of the entire structure.

In addition to the damage categories, the BAR methodology also includes an evaluation of the type of the structure in three categories:

• The light structures category is assigned to traditional structures built using, cinder blocks, bricks, organic or locally sourced material with the roof built using thatch.

• The medium structures category is assigned to single-level, small to medium sized structures built using cement walls with roofs made out of metal or prefabricated material.

• The heavy structures category is assigned to multi-level and/or large structures built using cement walls or prefabricated material with a metal or prefabricated roofs

Comparison with other post-disaster assessment methodologies

The BAR methodology focuses primarily on the assessment of wind disaster damage to structures, while Copernicus EMS is intended to cover any type of damage, but in practice both use 4 equivalent categories to assess damage, from none to complete. In 2018, a study was conducted to evaluate the accuracy of the different damage assessment methodologies. It can be read here.