いっぽうだ (ippou-da): Keep becoming; steadily more
～いっぽうだ (ippou-da)
Meaning
Keep becoming; steadily more
Formation and usage
V（辞書形） + 一方だ
Nの + 一方だ
Explanation
Describes a continuing trend in one direction, often an unwelcome one; not a contrast between two sides.
Examples
会議の費用は増える一方だ。
The cost of the meeting keeps rising.
試験の費用は増える一方だ。
The cost of the exam keeps rising.
研修の費用は増える一方だ。
The cost of the training session keeps rising.
発表会の費用は増える一方だ。
The cost of the presentation event keeps rising.
面接の費用は増える一方だ。
The cost of the interview keeps rising.
How related patterns differ
つつ often joins actions by one subject; つつも concedes. かたわら links sustained pursuits. てからというもの marks a turning point; つつある an ongoing change, 一方だ a one-way trend, and おきに a recurring interval.