Competing proposals to revamp Philadelphia's 40-year-old zoning code are before City Council. These measures come none too soon and should be debated openly and vigorously.

Philadelphia's zoning code is so old that nearly every development project of significance requires either a hardship variance from the Zoning Board of Adjustment or a parcel-based change in zoning by City Council.

This practice is known as spot zoning, changes to the way the city regulates building use, size, height and area on a site-by-site basis.

Spot zoning is a kabuki dance of uncertainty pitting sophisticated development lawyers seeking neighborhood approval against under-resourced civic associations looking for community benefits. It turns the Zoning Board of Adjustment and City Council into ad hoc planners, roles they shouldn't have to play.

Spot zoning is neither sound policy nor practice. It keeps the development world in a constant state of guessing, encourages backroom deals, and keeps community groups on the defensive to protect their little piece of earth.

It holds us back as a city.

Nobody is looking out for the greater good. Nobody is taking into account the impact of development-by-fiat on traffic, transit, infrastructure, neighborhood context, or quality of life.

Spot zoning yields mega-projects alongside three-story historic structures. It allows soulless parking structures to sit along once-vibrant retail corridors. And it enables gated communities to straddle the river's edge.

Progressive cities such as Chicago and New York understand the relationship between a modern zoning code and healthy economic development. They understand the role that city planning plays in structuring a rational and level playing field. They understand that a modern code that is enforced saves developers time and money because the rules are known. They have rewritten their zoning codes; smart planning and development are flourishing there.

We need to sweep away the cobwebs of a code that keeps us stuck in the dark ages of the development world. By embracing zoning reform and purging the system of spot zoning, we have a chance of becoming a healthier and progressive 21st-century city.

Harris Steinberg is an architect who runs the Penn Praxis program at the University of Pennsylvania.