As John White points out in The American Freight Car, most cars were really composites, not completely wood or steel, and even after steel cars had become the norm, wood had its uses and advantages.
ジョン·ホワイトが著書アメリカの貨車で指摘するように、ほとんどの車はまさに複合製で完全な木材や鋼製ではなく、鉄鋼の車が当たり前になった後でも、木材ならではの利点により使用された。