Four years later, there are a host of unanswered questions about the events of 9/11, including the unexplained and unprecedented architectural collapses of three office towers, and the extent of toxicity in the air of Lower Manhattan.
"Why Did WTC 7 Fall? [WTC 7]was...probably the first steel skyscraper anywhere to collapse solely because of fire. We still don't know why...according to FEMA's report on the collapse [the fire hypothesis] "has only a low probability of occurrence."
"How did the twin towers fall? Many FDNY personnel who saw the south tower collapse reported explosions at the lower levels as the top began collapsing. These reports, as well as "squibs" of smoke seen on video of the collapses, have led to theories that the towers were brought down in controlled explosions."
"Conspiracy theorists aren't the only ones who dispute [the official]version: Some fire scientists also take issue with [it]...And the point isn't just historical. The lessons learned from the WTC collapse will inform decisions about the safety of other modern office towers."
FULL STORY: Open and Shut

Planetizen Federal Action Tracker
A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

San Francisco's School District Spent $105M To Build Affordable Housing for Teachers — And That's Just the Beginning
SFUSD joins a growing list of school districts using their land holdings to address housing affordability challenges faced by their own employees.

Can We Please Give Communities the Design They Deserve?
Often an afterthought, graphic design impacts everything from how we navigate a city to how we feel about it. One designer argues: the people deserve better.

Engineers Gave America's Roads an Almost Failing Grade — Why Aren't We Fixing Them?
With over a trillion dollars spent on roads that are still falling apart, advocates propose a new “fix it first” framework.

The European Cities That Love E-Scooters — And Those That Don’t
Where they're working, where they're banned, and where they're just as annoying the tourists that use them.

Map: Where Senate Republicans Want to Sell Your Public Lands
For public land advocates, the Senate Republicans’ proposal to sell millions of acres of public land in the West is “the biggest fight of their careers.”
Urban Design for Planners 1: Software Tools
This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.
Planning for Universal Design
Learn the tools for implementing Universal Design in planning regulations.
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Transportation Research & Education Center (TREC) at Portland State University
City of Camden Redevelopment Agency
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