They provide rapid optimisation of layouts and also enable low-cost compliance with the necessary regulations and selective, rather than blanket, mitigation of 'risk hot spots'. Flame impingement on a piece of adjacent process equipment or storage can lead to rupture and maybe a fireball.
Blast waves caused by gas burning in congested areas can also cause damage.
This escalation is known as the domino effect and has to be controlled. PRT can show that you have optimised plant layout against potential accidents. Because you can backtrack to the source of the dominant problem, PRT also gives you priorities for planning safety improvements or for preparing for an emergency. Users can carry out rapid 'what-if' calculations to see the effects of changes in site layout or the addition of safety features. PRT is appropriate for a new project where options are being considered and for an established business that needs to write or update a safety case.