ExpSAFE Stand-Off Distances

ExpSAFE: Blast Stand-Off Distances is an ‘Quick Scan’ software tool that has been developed to conduct fast assessments of scenarios involving a structure or asset from a range of pre-defined IED attack vectors. The app is non-specific as predicting actual effects is far more complex requiring detailed knowledge of the improvised explosive device (IED), it’s placement with respect to asset, and specific understand of nature and construct of the asset. Nevertheless, the blast over-pressures provided in this application could assist façade and structural engineers in calculating blast responses of design and construction. Note the blast overpressure calculations were validated against US Army Technical Manual 5-855-1 ‘Fundamentals for protective design for conventional weapons’ (CONWEP). CONWEP is a recognised and appropriate modeling tool for calculating blast effects and is a well-validated model.

The application does not include damage from fragmentation as this is difficult to predict in relation to IEDs, which is why emergency procedures should advise sheltering behind a solid object. In relation to preferred distances for injury and damage, these are based on incident overpressure damage approximations found on the US National Oceanic & Atmospheric Administration (NOAA) - Office of Response & Restoration website (lasted updated 17 Apr 2019). The user should apply caution when referring to these preferred distances as knowledge of far field blast wave formation and interaction with structures will affect on actual damage.

KEY FEATURES OF THIS VERSION
- Ability to create and save assessments. No network connection is required as information is stored locally on the user’s device.

- Pre-loaded selection of IED types that range from small packages to delivery vehicles. The assigned amount of explosives or (net explosives quantity NEQ) is based on estimated capacity of the container and the type of IED attack vector.

- Calculated peak and reflected over-pressures are based on an user assigned distance for a selected IED type to the structure/asset under consideration. For comparison purposes, the US FEMA suggested minimum building distance is also shown.
 
- The preferred distance for a range of injury and damage thresholds are shown based on the IED type selected. The injury and damage approximations are based on incident (peak) overpressure.

Disclaimer statement. 
The findings and conclusions reached in this application are not, and should not be considered, an opinion concerning absolute values or rectification requirements.  No warranty or guarantee whether expressed or implied, is made with respect to the data reported or the findings and conclusions expressed in this application.  

Acknowledgement & Further Reading
The developer would like to acknowledge Mr Don Williams CPP ASecM MIExpE IABTI IAPS who is a recognised thought leader in security, emergency management and related disciplines.  His book “Bomb Safety and Security: the Manager’s Guide” is available from Amazon.  dsw57@internode.on.net This book is an excellent source for understanding the concepts behind this application and the terminology used.