How Los Angeles leads the way in cutting congestion

Downtown Los Angeles during evening rush hour.

When one hears the words “Los Angeles” and “traffic” in concert, the image that comes to mind is not often very pleasant. After all, statistically-speaking, Los Angeles has the worst vehicular congestion in the United States. The city is infamous for its creeping freeways and fabled stories of painfully long commutes. An average 5-mile drive through the L.A. basin takes at least 30 minutes due to traffic, and during peak travel times, that figure almost doubles. Rush hour results in slightly over 80% of the road network becoming gridlocked. To the average Angeleno, this accumulates to an extra 92 hours spent in the car per year.

These figures may prompt one to ask: why is traffic so horrendous in L.A.? What factors contributed to this situation?

Source of the Problem: Sprawl and… Density?

Los Angeles sprung forth through land grants and annexations, exploding from its original 28 square miles to engulf 503. However, this figure dramatically undersells the city’s actual urban growth. Greater Los Angeles spans an incredible 33,954 square miles (87,490 sq. km) of land. For comparison, that is roughly the size of South Carolina.

However, unlike South Carolina’s population of 4.6 million, Greater L.A. contains a total of nearly 19 million people. Contrary to popular conception, this makes Los Angeles one of the most densely populated cities in the country. No wonder Angelenos spend so much time stuck in their cars.

Killing Congestion

To tackle travel delays in increasingly populated and built-out American cities like Los Angeles, planners need to employ data-driven technology, improve access to modes other than the personal vehicle, and restrict or incentivize certain methods of commuting. Los Angeles has taken an unprecedented step in mitigating its crowded streets with coordinated and systematized traffic lights. However, this solution alone does not strike at the crux of the matter, for an overwhelming majority of Angelenos still commute by personal vehicle. This is despite extensive investment in public transit from the city government. Planners should respond to this imbalance by placing intentional limitations on private vehicular use to encourage a change in commuter behavior.

Synchronized Traffic Lights = Coordinated Control

Unexpected high volumes of vehicles and organically occurring shifts in traffic patterns create packed arterial roads and bottlenecks at busy intersections. Monitoring and remotely controlling traffic lights uses existing infrastructure to wisely coordinate the flow of traffic in relation to traffic density. Traditionally, shifts in traffic patterns cause major congestion before a city can address the flow. This leads to a phenomenon where local roads surrounding larger arterial throughways see an increase in usage until they too become congested. Traffic engineers could only respond to jams on site by manually adjusting lights. When traveling to the sites of congestion, they would often become ensnared in the very jam that they were dispatched to remedy. Synchronizing traffic lights enable immediate, real-time responses to incidents, whether it be as impactful as alleviating a bottleneck by sensing the speed of vehicles on the route, or as simple as prolonging a green light or two for VIPs to reach a movie screening on time (the latter example perhaps only applicable in L.A.).

By 2013, Los Angeles became the first major city in the world to completely synchronize all of its 4,400 signalized intersections with the completion of the Automated Traffic Surveillance and Control (ATSAC) System. This accomplishment has had a dramatic impact on the city’s roadway congestion and on the region’s carbon emission output. The Los Angeles Department of Transportation reports that ATSAC has directly increased speeds by 16 percent and reduced travel time by 12 percent. An experiment conducted by a team from Texas A&M also revealed that ATSAC relieved delays caused by stopping as much as 43 percent on certain arterial roads. A Data Impacts case study found that the launch of the system is directly responsible for a one million metric ton reduction in carbon emissions and criterion pollutants. By retrofitting existing infrastructure with modern technological solutions, planners and other decision-makers can have a dramatic impact on not just local traffic, but the global environment.

View from the Santa Monica Mountain Range.

Just a Drop in the Ocean

While the data-driven management of traffic flow decreases carbon emissions and the severity of vehicular congestion, it does not address another serious concern that planners have for the future of urban areas: the growing amount of cars on the road. With an increasing population, Los Angeles’ roadways are expected to transport more and more vehicles in the coming decades. ATSAC’s impact will be curbed by a steadily expanding tide of personal vehicles.

Widening Roads Does Not Solve Congestion

Attempts to address this impending problem have already been made, such as the widening of the 405 Freeway through the Sepulveda Pass. However, even though the $1.1 billion project was predicted to reduce congestion through the pass, the result was the inverse. Commuters who had previously avoided the freeway during their daily commute now flocked to the 405, only to experience a worse bottleneck and a longer wait than before. This phenomenon of commuter behavior relates to the involved principle of “triple convergence.”

Off the 405: Santa Monica Blvd. and Sawtelle Blvd. during peak rush hour.

Triple convergence is essentially a process where a city’s transportation network adapts to changes and interacts with self-adjusting relationships among different routes, times, and modes, resulting in an equilibrium. This principle at play explains why Los Angeles could not alleviate rush hour congestion by expanding the 405’s capacity. Although the freeway is the most traveled route per day in the city (and in the entire country), it is only a part of the larger transportation network. Expanding it pulled drivers that used local roads through the Hollywood Hills and public transit alternatives away from their routes, along with drivers that used the 405 at earlier and later times in the day, to use the freeway during peak hours. The principle of triple convergence explains why the 405 slowdown returned with greater severity.

Encourage Use of the Existing Public Transit System

To address the intensity and duration of traffic jams, cities need to think less about building and enlarging infrastructure, and more about how to drive commuters to utilize existing and underused transit systems. Encouraging commuters to concentrate their trips using less-traveled networks with comparable travel times creates a better system-wide equilibrium.

Los Angeles is a perfect example of a city with lop-sided commuter behavior, even after the city expended a substantial amount of money to beef up its public transit. A 2015 American Community Study found that 83.2 percent of Los Angeles’ 1.9 million workforce commutes daily by car. 74.1 percent of those commuters drive to work alone, up from 72 percent in 2010. These figures compare to the staggeringly low 6.1 percent of Angelenos that ride public transit to work, down from 7.2 percent in 2010. (For comparison, the same study found that 57 percent of commuters in Chicago drive to work versus the 28.2 percent that take public transit, four times the amount in Los Angeles). Therefore, 1.4 million commuters pour onto the streets and freeways of Los Angeles driving to and from work, hence the infamous congestion. Meanwhile, the city’s buses, light-rails, and subways, which cover a substantial amount of turf, remain relatively underused. The extended Expo Line that runs from downtown to Santa Monica, a 45-minute track, garners less than 10 percent of the I-10 traffic, which can take up to 2 hours during peak travel times.

The increase in auto commuters is a phenomenon despite the substantial expenditures in building new subway and light-rail lines. Even with a staggering $9 billion investment in public transit, the Los Angeles Metropolitan Transportation Authority reports that boardings are down 10% from 2006 to 2015. Ridership peaked three decades ago and has never recovered to its former numbers, even though buses were the county’s only form of public transportation in the 1980s.

Graphic from the LA Times article, “Billions spent, but fewer people are using public transportation in Southern California”

Incentivizing Driving is the Enemy

Parking near Santa Monica Beach

The lack of mass transit alternatives is not what drives commuters to get behind the wheel, but the convenience of driving. Unlike other dense cities such as New York or San Francisco, Los Angeles provides ample parking for its drivers. A 2015 study in the Journal of the American Planning Association found that “14 percent of incorporated land in Los Angeles County is committed to parking.” This translates to 18.6 million parking spaces, or 138 percent more spaces than people. Jeff Wattenhofer of Curbed Los Angeles argues, “the perception that there will always be available parking leads drivers to neglect public transportation options, contributing to traffic, as well as to the increase in pollution caused by circling the block in search of a spot.”

Other cities, such as San Francisco, have developed in ways that actively discourage commuting by car. Driving to work in San Francisco is more expensive and time-consuming than taking public transit. While a one-way fare for Muni costs $2.25 and lasts for 90 minutes of continued use for transfers, daily parking in downtown can run anywhere from $10 to $51. The city also created twenty-nine permit parking zones to limit street parking, which generates $10.2 million in revenue per year. The number of commutes made by car in S.F. is diluted by restrictions on driving. The U.S. Census Bureau reports that in 2015, only 35.3 percent of San Francisco commuters drive alone to work compared to the 34.7 percent of commuters that take public transit (along with the 10.4 percent that walk, 6.5 percent that carpool, and 4.3 percent that bike).

San Francisco, CA

A Coordinated Effort is the Key

By restricting parking and increasing parking prices, Los Angeles can disincentivize commuting by car. Commuters traveling to and from work would then seek alternate, more convenient options and lessen the burden on Los Angeles’ roadways. Certain communities of Los Angeles County, such as West Hollywood, have already implemented permit parking; however, if the overall metropolitan area is to experience an impact, there needs to be a greater coordinated effort in reducing parking availability. The Journal of the American Planning Association study agrees with this assessment: “planners should encourage the conversion of existing parking facilities to alternative uses.”

The expansion of the mass transit system in Los Angeles would then be met with an additional increase in the volume of customers and revenue, pulling commuters away from both their cars and the clogged roadways. A more balanced transportation system would not only reduce total commute time, but would also decrease the amount of idling hours an average commuter spends a year in stop-and-go traffic (it’s currently 81 hours a year).

Taking the Right Steps

Though it faces colossal challenges with congestion, Los Angeles is poised to be a leader in producing 21st Century solutions for 20th Century car-oriented planning. The unprecedented total synchronization of the city’s traffic light system and the ongoing efforts to change commuter behavior are important steps in realizing a future city where one’s workweek is not defined by wading in a sea of taillights on the 405.

San Diego-based writer. Interested in urban planning, languages, cultures, travel, history, and fiction.

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