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Analysis | Leaving downtown at rush hour in America's largest cities

Last updated: 08-13-2017

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Analysis | Leaving downtown at rush hour in America's largest cities

Tampa
Miami
There are vast swaths of America that are not easily accessible from America’s largest cities. And if you limit travel time to an hour, you might not get far from city limits.
Don’t forget about rush hour
How far you get in an hour often varies based on when you decide to leave.
Using billions of anonymous measurements from cell phones and vehicle sensors, Here Technologies, a location platform company, calculates how traffic conditions change throughout the day, said Alex Gordy, director of the company’s product management for traffic. That information can be used to predict how far you can get if you depart at rush hour versus later at night.
In Boston, you can drive a full 20 miles farther if you leave at 10 p.m. than if you leave at rush hour. Twenty miles might not seem like much, but in tightly packed New England, it’s the difference between being stuck in Massachusetts or escaping to neighboring Rhode Island or New Hampshire.
Compare that to Houston — a city with more than three times as many people as Boston — where you can travel almost 50 miles in one hour no matter what time you depart.
How far you can travel from downtown in one hour
Leaving at 4 p.m.
St. Louis
Las Vegas
Comparing traffic between cities is difficult, said Joe Cortright, president of Impresa Consulting, which specializes in metropolitan economies. If you focus only on the difference in travel time at rush hour, you miss the fact that in some cities, people just drive more, period. Sure, you can zip along at 60 miles per hour in St. Louis at any time of day, but you’re also much more likely to live farther from work, he said.
And you can’t alleviate traffic by just building more roads. That’s the “ fundamental law of road congestion ,” which says that when a new highway is built, it just increases the amount that people drive. That’s not necessarily bad — it can mean people gain more access to jobs and other opportunities they wouldn’t otherwise be able to reach.
So what is behind nightmarish traffic? According to Cortright, it’s about zoning and segregation. The model of the modern American city, with separate sections for living, working, shopping and eating, spurs congestion.
Gridlock in action
Nowhere is the rhythm of traffic more visible than in Los Angeles. Should you decide to leave at 4 p.m., you probably won’t get far.
Start in the afternoon and you’ll barely make it to Long Beach, about 25 miles south. Leave at night and you can get almost twice as far. Compare that to Dallas, the fourth largest metro area, where traffic is less apparent.
Area accessible in one hour at
4 p.m.
75 mi.
75 mi.
Los Angeles is cornered by the ocean to the west and the mountains to the north. But L.A. is “particularly tricky,” said Madeline Brozen of the University of California at Los Angeles Institute of Transportation Studies, because it’s “a city of a thousand villages without a center.”
Jobs have cropped up in the adjoining coastal towns without affordable housing in those areas, exacerbating the problem, she said.
Leaving Las Vegas
A half-dozen freeways run through the heart of Las Vegas, producing a spidery pattern that hardly changes during the day. The city, however, is in the middle of the Mojave Desert so you can drive for an hour without hitting much besides Paradise (a town adjacent to Las Vegas).
Compare the spindly shape of Las Vegas to the star-shaped pattern surrounding Nashville, where you can reach most of the city suburbs, spread throughout the surrounding area, within an hour.
Area accessible in one hour at
4 p.m.
Southeast
Northeast
There’s a reason why escaping a city like San Antonio is so much easier than leaving Philadelphia, which has roughly the same population. The pattern of access and how it changes throughout the day reflects a city’s geography, economy and history.  
West Coast
Many West Coast cities are sandwiched by the Pacific Ocean and mountains to the east, squeezing traffic along a few big interstates that slow down at rush hour. And escaping downtown Seattle or San Francisco might require crossing a bridge.
Traffic patterns also reflect a city’s activity, Brozen said. At 10 p.m. in Los Angeles, people might be cruising down Sunset Boulevard, making the streets busier than they would be in a sleepier town. In that way, traffic is an expression of a thriving local economy.
Area accessible in one hour at
4 p.m.
75 mi.
Southwest and west
There are huge sections of the country accessible in an hour from the downtowns of most Western cities. That’s partly due to the relative lack of lakes, oceans and mountains. But commuting patterns are also car-centric, with workers spread throughout the suburbs surrounding the city.
These areas are growing fast. Austin’s population, for example, grew about 20 percent between 2010 and 2016. That means there are more cars on the streets, but it also means more roads are built as people commute from farther away. Plus, cities in the West don’t always have the same public policy restrictions around development as older cities in the East and Midwest, Lomax said.
Area accessible in one hour at
4 p.m.
75 mi.
Northeast
Because many East Coast cities developed well before the invention of the automobile, they weren’t designed for cars in the first place. That, along with the density of homes and businesses in the oldest part of the country, is evident in the congestion that develops at rush hour.
While New York has a well-developed subway system (despite its recent trouble) it’s the hardest city to escape by car. No matter what time you leave, you can’t make it much farther than 30 miles from Manhattan in an hour.
Area accessible in one hour at
4 p.m.


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