How long will it be before a driverless car says to a pedestrian, "Get out of the way!"

Imagine a green light and a crosswalk littered with stragglers. It's a common problem for drivers — one that usually results in some yelling out the window or perhaps a hurried hand wave. Yet now, as cars prepare to ditch their drivers, we are left with one nagging problem: How will self-driving vehicles communicate with people?

Alphabet (which owns Google) is attempting to answer that question with a new patent addressing pedestrian interaction that lays out some options. Originally filed in 2012, the company received the patent on November 24.

The 22-page document includes some expected technology aims — Alphabet says it may equip its autonomous cars with sensors that can detect objects around them -- namely, pedestrians attempting to cross the street. The sensors would be designed to determine whether or not a vehicle's path is likely to be obstructed by a pedestrian, according to the patent, allowing the car's computer to decide on the right course of action: whether to stop, slow down or keep going.

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More interesting, though, is where the patent also outlines options for the driverless car to notify pedestrians of its intent, including a physical signaling device, an electronic sign or lights, or even a speaker that could provide audio communication. Different possibilities are detailed in sketches, with one example showing a stop sign on the front side door and another with a "Safe to cross" sign below the windshield.

The would-be exchange laid out in the patent is not unlike the one between traditional drivers and pedestrians — take a look around, make a decision, then communicate that decision. The only difference is that people crossing the street would now be interacting with computers and receiving cues from screens or speakers instead of from a fellow human being.

According to the document, "The notifications may replace those signals initiated by a driver, such as making eye contact with, waving to, speaking to, or flashing lights to a pedestrian while also sufficiently reassuring the pedestrian that it is indeed safe or not safe to cross the roadway."

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The patent signals Alphabet's intent to address safety issues, which may in turn help the tech giant tackle regulatory hurdles — key to broader acceptance of driverless cars. Asked when the company's self-driving cars would be mainstreamed, Google X's public policy director, Sarah Hunter, told a conference panel in the fall, "Whenever the DMV pass their operational regulations."

Earlier this week the company announced that its driverless car unit, until now part of Google X, will become a separate operating subsidiary as part of the restructured Google.

"Person-to-car communication is within the DoT's vision for the future," said Aaron Steinfeld, an associate professor at the Robotics Institute at Carnegie Mellon University.

He explained that a lot of emphasis is put on dedicated short-range communications (DSRC), or the sort of transmissions that alert a pedestrian to a nearby autonomous car via their smartphone. Google's new patent addresses the flip side of the communication issue — the car's perspective. As Steinfeld put it, "It's signaling its awareness of you."

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Other companies are dappling with this kind of technology, too. In October, Nissan unveiled a concept car with a dashboard display that signals in electronic blue text what the vehicle plans to do. In Nissan's vision, the car would be able to flash messages, like "After you," to pedestrians.

Apple's interest — and recent investments — in a driverless car have also attracted much attention and speculation.

Samsung also recently set up a unit to focus on automotive initiatives.

Car service company Uber, the most valuable private company in the world, has also been pouring money into driverless cars.

Regulators have been struggling to put pen to paper to cover the revolutionary auto technology. But there is little debate that communication is crucial.

Despite the buzz about safety, self-driving cars are actually known to be pretty cautious — sometimes to their own detriment. In fact, one of Alphabet's driverless vehicles was pulled over in November for driving too slowly. So while implementing communication technology would certainly make pedestrians more comfortable, it might also enable these cars to take a more realistic role on the road, without the rage associated with human drivers.