even more; all the more; to make matters worse (adds emphasis that something increases or is intensified)
雨で電車が遅れ、いやが上に道路も渋滞していた。
The trains were delayed by the rain, and to make matters worse the roads were also congested.
彼は失敗した上に、いやが上に嘘までついて信用を失った。
He failed, and worse still he lied and lost people's trust.
期待していた発表が延期され、いやが上にも不安が増した。
The announcement I had been expecting was postponed, and my anxiety grew all the more.