ATRI says higher speeds at Spaghetti Junction could save millions

March 6, 2019

Tyson Fisher


Congestion at the Interstate 285 and Interstate 85 interchange in Atlanta – known as “Spaghetti Junction” – can be a bottleneck nightmare for truckers. Research recently published by the American Transportation Research Institute found one possible solution that can reduce fuel consumption and emissions at that interchange.

In a study published on Tuesday, March 5, titled “Fixing the 12 Percent Case Study: Atlanta, Georgia Fuel Consumption and Emissions Impacts,” ATRI focused on the interchange of I-285 and I-85 in Atlanta in a series that seeks solutions for 12 percent of interstate miles that are responsible for nearly 90 percent of the trucking industry’s congestion costs.

According to ATRI’s research, average speeds at the interchange during the weekday morning commute drop to as slow as 28 mph, with evening commutes experiencing even slower speeds as low as 14 mph. Average speed during peak periods is 23 mph, with nonpeak periods average at 47 mph. Overall average speeds are 40 mph throughout the weekday and 49 mph during the weekend.

With 2.92 million vehicle miles traveled at current speeds, nearly 40 million gallons of gasoline and more than 15 million gallons of diesel are burned at Spaghetti Junction each year. If average speeds were raised to 55 mph, gasoline consumption can drop by nearly 3 million gallons and diesel consumption can decrease by nearly 2 million gallons. At the current EPA national diesel price average at $3.076, which can save the industry nearly $5 million a year at that interchange alone.

Accounting for emissions, vehicles currently release 757 tons per year of NOx, 139 tons per year of Reactive Organic Gases (ROG), 32 tons per year of PM2.5 (particulate matter with a diameter of less than 2.5 micrometers) and 558,933 tons per year of CO2. If average speeds are increased to 55 mph, those emissions will reduce by 5.5 percent for NOx, 14.7 percent for ROG, 17.1 percent for PM2.5 and a reduction of 8.2 percent for CO2.

Although ATRI explains the effects of average speeds at 55 mph, the research does not offer any suggestions for achieving an increase in average speeds.

According to ATRI, congestion nationwide has increased trucking fuel consumption by nearly 7 billion gallons in 2016. From an economics point of view, that comes out to an additional $15.74 billion in fuel costs.

Spaghetti Junction is consistently ranked as one of the worst bottlenecks in ATRI’s annual bottleneck report. This year, Spaghetti Junction ranked second after a three-year run as the worst truck bottleneck.

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