How do engineers explain mysteries such as phantom traffic jams and why a brief drop in volume can trigger a traffic jam?
" 'Weaving is the worst condition for traffic flow,' says Prof. Polus. Because drivers in heavy traffic brake when a car pulls into their lane, and because it takes time to get back up to speed, there are larger and constantly-changing gaps between vehicles. That invites yet more cars to change lanes, propagating a wave of stop-and-go traffic that cuts the number of cars in a stretch of road by about 10%, calculates Prof. Polus, who will present his work at the 16th International Symposium on Transportation and Traffic Theory at the University of Maryland this month. That may not sound so dire, but in rush hour the result is a five-mile backup, his calculations show. In congestion, be content with the lane you're in."
[Editor's note: The link below is available for a period of 7 days.]
Thanks to Chris Steins
FULL STORY: How Brief Drop in Cars Can Trigger Tie-Ups, And Other Traffic Tales

Trump Administration Could Effectively End Housing Voucher Program
Federal officials are eyeing major cuts to the Section 8 program that helps millions of low-income households pay rent.

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

Ken Jennings Launches Transit Web Series
The Jeopardy champ wants you to ride public transit.

Driving Equity and Clean Air: California Invests in Greener School Transportation
California has awarded $500 million to fund 1,000 zero-emission school buses and chargers for educational agencies as part of its effort to reduce pollution, improve student health, and accelerate the transition to clean transportation.

Congress Moves to End Reconnecting Communities and Related Grants
The House Transportation and Infrastructure Committee moved to rescind funding for the Neighborhood Equity and Access program, which funds highway removals, freeway caps, transit projects, pedestrian infrastructure, and more.

From Throughway to Public Space: Taking Back the American Street
How the Covid-19 pandemic taught us new ways to reclaim city streets from cars.
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.
Heyer Gruel & Associates PA
Ada County Highway District
Institute for Housing and Urban Development Studies (IHS)
City of Grandview
Harvard GSD Executive Education
Toledo-Lucas County Plan Commissions
Salt Lake City
NYU Wagner Graduate School of Public Service