Freight Car Brake Pipe Pressures?

[Sean R Das]

I remember reading in Model Railroader Cyclopedia Volume 1: Steam Locomotives that during the steam era, brake pipe pressures were 70 psi for freight and 90 psi for passenger trains.

However, today, freight train brake pipe pressures have increased to 90 psi. Around what year was this change made? Why?

 

[RailroadJeep]

IIRC, BN was still using a 80 PSI BP up untill the mid or even late 80's, but used 90 PSI for mountain grade.

 

[roee]

90 PSI for Freight, 110 for Passenger.

 

[SuperToad]

The higher the brake pipe pressure the more air you have to make multiple applications. This becomes more important while comming down grades. Passenger cars use more air for doors, toilets ect so they can use the extra pressure to run those things as well as air for braking.