The $8 million box sits unmolested but detested beside a pillar in a tunnel that carries four lanes of traffic near the very heart of town.

It clicks, it flashes, it clicks, it flashes.

That box and the cameras inside it have generated 61,061 speeding tickets in the past seven months, transferring $8.1 million from the wallets of K Street drivers into the District’s treasury. The cameras, which sit where four lanes of K Street dip under Washington Circle, are on pace to set a District record for cash earned by a speed camera.

There are orange warning signs — “Photo Enforced” — hanging beneath the 25 mph signs on either end of the tunnel, but they are missed or ignored by an average of 305 drivers a day who receive speeding tickets in the mail.

The revenue from speed cameras and red-light cameras has grown to become a noteworthy piece in the District’s $12.1 billion budget since the devices made their debut 14 years ago. Overall, they took in $84.9 million in fiscal 2012. Since the current fiscal year began Oct. 1, the 10 most-profitable speed cameras have issued $29.5 million in tickets.

A windfall from Washington’s speed camera

Some who are ticketed complain that the District is out for the money rather than being concerned about safety or the law. City officials deny that charge.

Safety experts say people should not use that defense for violating speeding laws.

“The opposition is a reflection of the public’s inability or unwillingness to view speeding as a safety issue,” said Jonathan Adkins of the Governors Highway Safety Association , a coalition of state safety officials. “Some states reported that when gas prices were very high, speeds decreased. So, maybe once the public feels they will get a ticket if they speed, we will see a change. Drivers may slow down to save a buck but not slow down to potentially save a life.”

There is a solid body of research to support the argument that cameras reduce the risky behavior that causes accidents. Speeding was a factor in about a third of all traffic deaths nationwide, and the rate has been about the same in the Washington region, although in 2010 it played a role in 38 percent of the fatalities, according to data compiled by the regional transportation planning board.

The wide mix of state laws on speed-camera use seems to reflect the relative novelty of the tool. Twelve states expressly prohibit use of speed cameras; seven states permit limited use; the District and two states allow them; and 29 states have no laws regarding them.

Virginia has no law on speed cameras. Maryland limits speed cameras to work zones and school zones.

In a world where many drivers treat the speed limit more as a recommendation than gospel, and where a police officer with a radar gun has been considered bad luck rather than a high probability, the advent of speed cameras already has seen results.

When people in the District learn of a camera’s location — and they are posted on the police department’s Web site — they slow down to the speed limit as they approach. The drivers behind them may not know the reason for the relative crawl, but they have no choice but to slow down, too.

That leads to a question: As the District becomes accustomed to the tens of millions of dollars in camera fines, will it run low on cash if more people begin obeying the law? Once again, the fact that these devices are relatively new to the urban landscape makes the answer unclear.

“Does there come a point where the city’s not making money or even losing money? I think that’s a possibility in the long run,” said Anne T. McCartt, senior vice president for research at the Insurance Institute for Highway Safety. “That certainly would be the ultimate goal from a safety point of view. In the long run, you would expect violations to go down. That’s the purpose, and that’s going to happen.”

But she doubts speed cameras will grow so effective that they put themselves out of business. “Experience would say that drivers really like to speed; it’s hard to persuade people not to speed,” she said.

So far this fiscal year, the camera inside a 5-foot-tall steel box on K Street is by far the most productive in the District. After its $8.1 million in revenue, a camera on southbound D.C. 295 ranks second with 33,495 tickets valued at $4.6 million. The previous year’s leader, in the 600 block of New York Avenue NE, is third with 31,949 tickets worth $4.7 million, a drop in volume but increase in value because it is now in a work zone where fines are higher.

Rounding out the top speed cameras: another on D.C. 295, this one on the northbound side (19,685 tickets, $3.1 million); 2200 block of South Dakota Avenue (17,685 tickets, $1.7 million); 3500 Massachusetts Avenue (13,618 tickets, $1.5 million); two more cameras on D.C. 295, one southbound (13,172 tickets, $1.5 million) and one northbound (12,350 tickets, $2.4 million); and 1900 Branch Avenue (10,819 tickets, $1.8 million).