South Carolina Department of Transportation: 2017 Total Eclipse

What Happened

The solar eclipse of August 21, 2017 inspired millions of people to travel to the eclipse’s path of totality. South Carolina was one of those states that was plunged in total darkness.

SCDOT’S Response

The South Carolina Department of Transportation (SCDOT) anticipated substantial travel, especially on major interstates such as I-95, I-77, I-85 and I-26.

Long before the eclipse, SCDOT posted messages on electronic displays to encourage travellers to plan ahead.

SCDOT made a Traffic Management Plan to restricting roadwork, and increase patrols and other services. They also worked to prepare 511 real-time traffic information for all SC interstate highways.

CATT Lab conducted an after-action review for SCDOT to analyze its performance in easing congestion during this rare event.

Identify Areas with the Greatest Impacts to Traffic

The total eclipse arrived on the state’s western border at 2:36pm and passed the Atlantic coast at 2:48pm. Four RITIS tools were used to examine the chronology of events.

The Region Explorer tool was used to compare bottlenecks before and after the eclipse. Using data stored by RITIS, it found 230 bottlenecks at 11:30am, and 396 bottlenecks after the eclipse, at 4:00pm. With Region Explorer’s map-based interface, it was easy to identify areas with the most bottlenecks.

Another tool was used to focus on I-95, comparing traffic speeds on the day of the eclipse to the previous two Mondays. Congestion Scan visualizes traffic speeds as a heat map, making it easy to visually compare normal traffic with a special event, both spatially and temporally.

Trend Map is normally used to create an animated map of changes, but is also useful for visualizing traffic metrics on a map. For example, Trend Map can be used to create before and after snapshots of I-95, showing substantial speed reductions from I-26 to the Georgia border the day of the eclipse.

Next up, Performance Charts can be used to plot speed metrics over the course of the day. You can get overlapping plots for a range of time periods, making it easy to compare the event day with normal days. SCDOT discovered an overall decrease of 24% to 38% the evening of the eclipse from the previous two Mondays.

Quantify & Display Various Cost and Delay Metrics

The User Delay Cost Analysis tool can be used to attach a financial cost to the congestion caused by the eclipse. SCDOT created a heat-mapped spreadsheet of hourly traffic costs, pinpointing the 4:00pm to 9:00pm time range as having the cost due to traveller delays.

The PDA Suite provides a broad range of analytics that could be used to evaluate the traffic impacts that occurred, and gain additional insight to improve future major event traffic management and travel advisories.