How green is my alley?

This summer the City of Milwaukee Comptroller's office found that the replacement cycle for the city's streets and alleys was several years longer than their predicted useful life. For alleys, the replacement cycle was found to be 272 years, or 4.5 times the useful life of an alley. The response from the Mayor was to hasten the replacement cycle, which garnered general agreement and support.

Interestingly, the New York Times reported this week that the City of Chicago is also focused on replacing alleys:

Chicago has decided to retrofit its alleys with environmentally sustainable road-building materials under its Green Alley initiative, something experts say is among the most ambitious public street makeover plans in the country. In a larger sense, the city is rethinking the way it paves things.

This initiative was prompted by the fact that its hundreds of miles of aging alleys needed replacement. Says Janet Attarian, the project's director, “The question is, if you have to resurface an alley anyway, can you make it do more for you?”

Chicago has found that the answer is yes. They will now pave all alleys in such a way as to filter rainwater, reduce run-off, and recharge groundwater, while reducing heat retention in the summer and reflecting heat in the winter. The cost? About the same as traditional paving, divided between materials (porous concrete) and labor (creating a stone filtration layer).

Milwaukee would be smart to consider making a similar investment in its alley infrastructure. Things to investigate: Would the cost of porous paving be more than traditional paving? Would the maintenance costs differ significantly? Would the useful life spans differ significantly? If the answers to all these questions are "no," green alleys could be a feasible option for our city, as well.