Mayor Michael Nutter has returned legislation allowing three-dimensional digital billboards in Center City to City Council without his signature, according to a letter Nutter released on Thursday.

The bills become law without his signature, but Nutter said in the letter that he supports and will sign an amendment to the legislation introduced Thursday. The amended version, which Councilman Mark Squilla drafted in coordination with the Nutter Administration, includes a more rigorous approval process for each “Urban Experiential Display,” and emphasizes traffic safety, according to Nutter.

“I understand the concerns of those who have objected to UEDs,” Nutter wrote in his letter, “but also recognize that in certain locations, well-designed displays, compatible with their surroundings, may in fact add to the landscape.”

The new bill clarifies that yearly payments from the sign builders must go through a government entity that will give them out as grants for public improvements. Under the original legislation, the payments—around $125,000 per year—would go directly to a few nonprofit groups, including the Reading Terminal Market, Friends of the Rail Park, and Friends of the Avenue of the Arts.

Under the legislation, Catalyst Outdoor will be permitted to construct two large, 3-D, digital billboards, called “Urban Experiential Displays,” outside the Convention Center at Broad and Arch streets and across from Reading Terminal Market at 12th and Arch.

Catalyst’s president, Thaddeus Bartkowski, donated nearly $10,000 to City Council members in the last few years. The company also hired former Councilman Frank DiCicco as a lobbyist to help get the legislation passed, and engineered a supportive write-in campaign to Councilman Squilla.

Note: an earlier version of this story said the original legislation would not become law without Nutter’s signature. The bills have become law, and Squilla’s current bill would amend that law. PlanPhilly regrets the error.

Read Nutter’s full letter below.

TO THE PRESIDENT AND MEMBERS OF THE COUNCIL OF THE CITY OF PHILADELPHIA:

I am hereby returning to your Honorable Body Bill Nos. 140906-A and 140907 without my signature. This pair of bills provides for the zoning, review, and permitting of “Urban Experiential Displays” or UEDs. These proposed electronic displays would carry advertising and other visual material.

I understand the concerns of those who have objected to UEDs, but also recognize that in certain locations, well-designed displays, compatible with their surroundings, may in fact add to the landscape. Bill Nos. 140906-A and 140907 are a start, but I have significant concerns about them.

Missing is any kind of design review capable of ensuring appropriateness. There is also no certainty that critical traffic safety issues will be taken into account for each and every proposal. And as the legislation now stands, community benefit agreements, which have been integral to this proposal from the start, would be unenforceable by the City, and provide zero accountability for either the developer or the community organization.

For these reasons, I cannot sign these bills at this time. However, the Sponsor—Councilman Mark Squilla—and members of my Administration have worked hard to resolve the outstanding issues. That resolution is embodied in a further bill Councilman Squilla is introducing today. It provides for rigorous review and approval of each UED to ensure the proposal is superbly-designed and appropriate to its location. It makes traffic safety a paramount requirement. And community benefits agreements can be enforced and overseen to provide real accountability. I support that bill, and will sign it.