WASHINGTON — The Secret Service is adding a second layer of steel spikes to the top of the White House fence to keep would-be intruders at bay, according to a proposal submitted to the National Capitol Planning Commission.

The 1/2-inch steel “pencil point” spikes will be snapped into place at the top of the fence and protrude outward, according to a diagram included in the proposal submitted for the Secret Service by the National Park Service. The commission approved the proposal at a hearing Thursday.

The spikes will be added along the north and south sides of the White House grounds starting Friday, the Secret Service and National Park Service said in a statement.

The Secret Service has been studying ways to improve security at the White House since a Texas man, Omar Gonzalez, climbed over the fence in a spot where a spike was missing and ran deep into the executive mansion in September.

The agencies said design concepts for long-term security changes at the fence are being reviewed, and a final design is expected to be selected this summer.

Construction is expected to begin in 2016.