An additional 1,100 parking meters designated for use by handicapped drivers will be installed shortly in the District in areas where there is a high demand for parking spaces for the disabled.

Installation of the meters, which are identifiable by their red tops, will bring to 1,500 the number of disabled-only metered spaces available by April 17, the District Department of Transportation (DDOT) said Thursday.

The increase means that about 9 percent of the District’s metered spaces will be reserved for disabled parkers, DDOT said. The District nets about $40 million in revenue from 17,000 parking meters.

More meters for disabled drivers will mean more parking-meter revenue for the District. Before the installation of the red-top meters, disabled drivers were allowed to park for free at regular meters for two hours, but they often parked for longer because ticket writers weren’t able to accurately determine how long the vehicle had been in the spot.

Some areas — notably the area around city offices at One Judiciary Square — had a very high number of cars with handicapped credentials parking for free.

Although people parking legally at the new red-top meters will be permitted to remain there for twice as long as cars parked in nearby non-red-top spaces, they will be required to pay to park.

DDOT said vehicles parked at red-top meters without a valid placard or plate designating a disability will receive $250 tickets. If disabled drivers park in non-red-top spaces, they will be required to pay the prevailing meter rate.