Dark photograph of a tunnel with blue lights

How Geotab ITS used a major bridge closure event to uncover key traffic and mobility information

When critical roadways unexpectedly shut down, the traffic repercussions are wide-ranging. Yet these closures also present a unique opportunity for transportation planners to collect and analyze critical data about local and long-distance traffic patterns.

Kentucky and Ohio faced a sudden and severe traffic disturbance when two large trucks carrying hundreds of gallons of fuel and chemicals collided in the early morning hours of November 11, 2020. Fire engulfed the Brent Spence Bridge, which connects Kentucky and Ohio and is a vital thoroughfare for commercial and non-commercial traffic along Interstates 71 and 75.

The aftermath of repairs and inspections left the bridge unusable for six weeks to facilitate repairs and conduct safety assessments. Without any warning, public and industry users were cut off from a major piece of the State’s transportation system.

Meanwhile, transportation stakeholders went into emergency response mode, devising alternate routes and detours to keep traffic moving. The bridge normally carries about 150,000 vehicles per day, with up to one-fifth of those being heavy trucks. All of these vehicles needed to find a new route. What would happen to that traffic, where did it come from and where did it need to go?

During the closure alternate routes of travel were put forward with the goal for commercial traffic to use the interstate as opposed to traveling through downtown Covington. As expected, the closure of the bridge resulted in significant traffic issues around and throughout the city.

 

Understanding how transportation planners manage unforeseen challenges

To really understand the impact of a major event like the Brent Spence Bridge closure, Geotab ITS leveraged its powerful new Altitude platform, to help perform a data validation exploration. Together with transportation planners, they gathered crucial, contextualized data about the bridge closure’s immediate consequences and future implications.

 

Aerial Google Map view of Brent Spence Bridge

 

To start off the analysis, Geotab ITS looked at the immediate bridge area before, during and after the closure. Both before and after the closure, general volume, speed and traffic patterns remained mostly unchanged.

Geotab ITS decided to do both volume and speed comparisons on the surrounding bridges, which served as alternate routes during the Brent Spence Bridge closure.

 

 

The data showed notable increases in volume on nearby bridges linking Kentucky and Ohio. Similarly, there was a notable negative impact on speeds on bridges and major surrounding intersections during peak AM and PM traffic.

 

Corridor analysis: Main Street

We took a look at Main Street which leads to the Bailey Bridge.

 

Aerial Map of Brand Spence Bridge Corridors

Charts of Brent Spence Bridge Corridor Traffic

 

Brent-spence-bridge-traffic

 

There was an upward of 500% increase in traffic heading North on Main Street, with a notable increase in the percentage of heavy-duty vehicles. During the closure, the data showed 50% of the Geotab-connected vehicles traveling were heavy-duty, an increase from the typical day pre- or post-closure rate of only 23%.

As expected, there was also a significant impact on travel times. During the closure it took almost 10 minutes for the slowest moving vehicles to get through Main Street compared to a typical time of 5 minutes. This data supports the pattern of traffic routing via Main Street to access Bailey Bridge.

 

Intersection analysis: Main Street and West 4th Street

Next, we analyzed the intersection at Main Street and West 4th Street.

Percentage of vehicles stopping (during closure)

 

Percentage of vehicles stopping (typical)

 

Given that both roads are used to access the Bailey Bridge, we saw a large increase in volume at the intersection of up to 237% which had a negative impact on the number of vehicles stopping at this intersection. Before the bridge closure, 21% of vehicles stopped at this intersection. During the closure the percentage increased to 46%. Unsurprisingly, travel speed and travel time were also negatively impacted.

 

General traffic overview: Interstate detours 

Additionally, we took a look at the interstates surrounding the bridge area that were recommended as detours. General volumes, speed and traffic patterns before and after the closure remained mostly unchanged –  as observed in the nearby bridges and intersections. As expected during the bridge closure, nearby interstates also showed an increase in volume. There was no significant shift in speeds on major interstates.

 

 

The I-275 saw an 114% increase in volume and the I-471 saw a 163% increase in volume, but nowhere near the increase that the bridges in the downtown Covington area saw.

 

Contextualized insights for more informed decision-making

The purpose of this analysis was to validate, understand, and highlight the changes in commercial traffic patterns before, during and after the bridge closure. Metrics that were analyzed included general volume comparison, general speed comparison, key corridor analysis and key intersection analysis. Geotab ITS was able to validate freight movement analysis to better understand the impact of the bridge closure and to inform future traffic mitigation strategies. Of particular importance was the ability to investigate the rerouting of heavy-duty vehicles as contextualized data that distinguishes vehicle class is not easily accessible. It is these contextualized insights from Geotab ITS that will help transportation planners alleviate disruptive traffic events that may impact the movement of goods on their road networks.

Learn more about how Geotab Intelligent Transportation Systems and the Altitude Platform can help unlock actionable insights, so you can start creating safer, more efficient and more sustainable cities.

 

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