Arup Study for TfGM on Virus Aerosol Transmission in Metrolink Trams

[Greybeard33]

Metrolink trams offer customers breath of fresh air in fight against COVID-19 (tfgm.com)

Transport for Greater Manchester (TfGM) commissioned global built environment and consultancy firm Arup to undertake Computational Fluid Dynamics (CFD) modelling of its M5000 trams – the first study of its kind in the United Kingdom.

The modelling assessed the air flow within the vehicle, with particular focus on how this relates to the potential for aerosol transmission of viruses, by looking at how exhaled breath spreads through the vehicle, and how that is affected by factors like opening windows, mask wearing and activity levels.

Metrolink’s trams are ventilated through fans on the roof and air diffusers in the ceiling, with air exhausted from under-seat vent holes.

Even with the ventilation system operating at half capacity, the study found that there were approximately 20 air changes per hour, which is better than the recommendation in a recent paper from the Scientific Advisory Group for Emergencies (SAGE).

[Arup’s modelling] found that the risk of infection was reduced by around two-thirds by passengers wearing face coverings.

I believe 20 air changes per hour is comparable with the ventilation rate in airliner cabins, and much higher than provided by most HVAC systems in buildings and heavy rail carriages.

 

[VauxhallandI]

[Arup’s modelling] found that the risk of infection was reduced by around two-thirds by passengers wearing face coverings.

I couldn’t see any evidence backing this statement up?

 

[yorksrob]

So basically, shove a fan in the roof and a grille in the floor of all your carriages and you're sorted.

 

[hwl]

Metrolink trams offer customers breath of fresh air in fight against COVID-19 (tfgm.com)




I believe 20 air changes per hour is comparable with the ventilation rate in airliner cabins, and much higher than provided by most HVAC systems in buildings and heavy rail carriages.

Uk heavy rail air change rate is 7-10 per hour based on recent research.

[Arup’s modelling] found that the risk of infection was reduced by around two-thirds by passengers wearing face coverings.

I couldn’t see any evidence backing this statement up?

That would be in the unpublished full report...

 

[yorksrob]

How does the change rate on heavy rail compare with open windows on non-air cin stock ?