Yes, as has been stated already in the thread. they are 1:24. They follow the LGB old american wood sided style rolling stock sizes pretty much bang on as is also the case for the USAT 'American' series.
The Delton cars are nicely moulded and with enough difference in details to make the cars a little more interesting and near prototypical depending on what lines etc you have running (that is if rivet counting might be the issue ;-) )