Sorry, Mayor Kenney, but it's hard to get too excited about the deal you have made with Philadelphia's building trades to potentially open their doors to more minority members.

This city has been down that road before and the unions are about as lily-white as they ever were. Or they seem to be. For decades, the unions have refused to reveal their demographics. But walk around the city and look at who's working construction and you easily get the picture.

The last reliable estimate of diversity in the trades was done in 2013 by former Inquirer reporter Tom Ferrick for the now defunct Axis Philadelphia, a nonprofit news organization. Using city Office of Housing and Community Development data, he concluded the city's trade unions were 99 percent male, 76 percent white, and 67 percent lived in the suburbs.

But even those numbers were deceiving. If you excluded members of the mostly minority Laborers International Union, 81 percent of the trades' members — carpenters, electricians, painters, etc. — were white. Until the unions share membership information, it's a good guess that not much has changed.

Give Kenney credit for addressing a disparity that not even the city's past black mayors — Wilson Goode, John Street, and Michael Nutter — could erase. Kenney announced Tuesday that the unions and city are launching a pre-apprenticeship program as part of the six-year Rebuild initiative to renovate, parks, recreation centers, and libraries.

Thirty people from low-income neighborhoods will be enrolled the first year and given the chance to become apprentices vying for full union membership. If that procedure sounds familiar you might be thinking of a similar deal that the trade unions and the School District agreed to in 2006.

The unions were supposed to make up to 425 apprenticeships available to city high school graduates over four years. Nearly 400 apprentices were recruited the first year, about half of them minorities, but the unions never provided data on how many eventually became members. Again, very few minorities are seen on construction sites.

Maybe that will change some since the Rebuild agreement also calls for minority workers to be 45 percent of the force hired to fix leaky roofs, replace outdated bathroom fixtures, resurface basketball courts, and otherwise improve dilapidated facilities across the city. Fifty percent of the workers at Rebuild sites must be Philadelphia residents.

More significant though may the deal's requirement that people with construction skills who get Rebuild jobs managed by the Philadelphia Redevelopment Authority will gain automatic membership to the trade unions. No one knows how many will meet the criteria.

The trades depend on the city for work. It's time they paid more than lip service to adding minority members. Kenney is trying to make that happen. But it won't unless he's more forceful than past mayors in insisting the unions live up to their end of the bargain, and be transparent about their progress.