MINNEAPOLIS — Fliers can stop sharpening their elbows. Overhead bins are getting bigger.

Packed planes and a high volume of carry-ons are forcing airlines to expand the space above passenger’s heads. United and Delta are the latest airlines to replace or upgrade bins so they hold more luggage. And engineers at Boeing are designing jet interiors with today’s bulkier luggage in mind.

It’s a chance to placate passengers who feel like they’re thrown into a roller derby every time they board a plane. Because of fees on checked bags, more passengers are bringing carry-ons, which are growing in size. And with planes more crowded than ever, bins fill up before everyone has reached their seat. Travelers fight physics and one another to shove one more bag overhead. Or they’re forced to check luggage at the gate.

The result is upset travelers, harried flight attendants and delays.

The percentage of passengers bringing bags on board has hovered around 87 percent in recent years, United Continental says. And “the size of the carry-on has increased. … They are stretching the limits of their bags,” says Scott O’Leary, managing director of customer solutions at United Continental Holdings Inc.

Expanding bins is a smart way for airlines to set themselves apart, says Henry Harteveldt, who leads airline and travel analysis at Atmosphere Research Group, a market research firm. “Especially if they cater to the business traveler, they’re hoping it will give them a small but noticeable competitive advantage.”