LOS ANGELES COULD BE QUIET
CITY OF CARS
Los Angeles is a city known for its cars. The reputation is not undeserved. LA, in recent years, has topped the list of cities with the highest car sales, the highest number of hours spent in traffic, the largest municipal street system, and the highest number of lanes in an urban highway. And all that highway noise makes it loud. An apartment next to a freeway registers at about 90 decibels, or “very loud”—in the same range as a gas lawn mower at three feet.
EXPERIMENTING WITH QUIET PAVEMENTS
The California Department of Transportation (Caltrans) has become the largest builder of noise walls among the 50 state DOTs. By 2004, Caltrans had built over 480 linear miles of noise barrier walls to mitigate freeway noise. Each mile currently costs $2.4 million. But Caltrans has begun to take an interest in “quiet pavements” that had been successful at reducing road noise in Europe. If decibel levels could be reduced by pavements instead of walls, millions in scarce highway improvement dollars could be saved. From 2002-2006, Caltrans built and tested five sections of quiet pavement in the high desert north of Los Angeles on SR-138 in a joint research effort with the Volpe National Transportation Systems Center. The hope was to get the data incorporated into the Federal Highway Authority’s Traffic Noise Model, the highway traffic noise prediction model that maps decibel levels at an urban scale.
A HUSHED CITY?
If quiet pavement is adopted by Caltrans for Los Angeles, wide swaths of the city could become quieter. Compared to Caltrans’ normal dense graded hot mix asphalt (HMA) surface mixes, open-graded friction courses (OGFC) and rubberized asphalt concrete were better at reducing noise in tests, according to Judith L. Rochat, Ph.D., former Physical Scientist with the Volpe National Transportation Systems Center.
The State of California has mandated that each city and county prepare a “ noise element section” as part of its general plan to measure and quantify noise from highways, freeways, and streets, among other sources. It is meant to provide guidance on achieving noise-compatible land uses. If quiet pavements could be predictively modeled, the “ noise element” of each city’s general plan would reflect lower noise levels compatible with higher value land uses.
PIONEERS OF HIGHWAY LIVING
In March, the Los Angeles Times reported that there was a surge in homebuilding near freeways. Between 2000 and 2010, the population within 500 feet of a Los Angeles freeway grew 3.9%, compared with a rate of 2.6% citywide. Between 2005 and 2015, the number of building permits LA granted increased sharply within 1,000 feet of freeways. In 2015 alone, the city issued building permits for 4,300 homes near freeways—more than in any year over the last decade. Developments like Orsini, Il Villagio Toscano, and Cedar Point have already been approved or built near the 101, 110, 405, and 60. Freeways might not be getting quieter yet, but the city is already beginning to close in.
What could a quieter city mean? The areas adjacent to LA’s 508 miles of freeway and expressway could become more desirable areas for living and easier to permit. More residential density next to major thoroughfares could modify neighborhoods and commercial areas to create a new urban form—the linear village. Existing property values near highways could increase. The quieter highways and reduced noise could also mean better health outcomes for those already living nearby. Studies show noise can cause additional stress, disruption of sleep, and heart disease. Overall population health could also decline as people newly drawn to these areas inhale more exhaust particulates.
OR THE FUTURE OF LOS ANGELES COULD BE LOUD
But LA is getting bigger. The city’s population just topped 4 million people. In 2014, Bloomberg predicted that greater LA will be the densest urban area in the US in 2025, with a population growth of 38.4%. That could mean more car ownership, more traffic, and more highway building. Cars themselves are trending bigger. Fifty years after its original release, the Ford Mustang in 2015 is 1,000 pounds heavier with triple the horsepower. Heavier, high-powered cars commuting farther as the metro expands can make the city louder for longer in the day. Today, data on noise is getting out of municipal planning offices and becoming more widely available through Soundscore™, a rating that aggregates environmental noise for a given location. Perhaps in the near future, people will map the noise of the city when looking at real estate listings and take refuge in the quietest areas, abandoning the highways to the mega cars and motor carriers atop their restless Freightliners.