With their low cost and relatively quick installation, pneumatic road tubes have long been the go-to standard for collecting volume-based traffic data. However, in recent years, we’ve seen cities steadily adopting safer, more efficient methods of traffic data collection, namely video.
Today, we’ll break down the difference between road tubes and video in order to better understand the shift in data collection methods. To get started, let’s level-set on the basics.
Pneumatic road tubes
While they serve as the standard in many cities, road tubes have several well-known issues when it comes to completing volume-based traffic studies and data collection. To start, road tubes put technicians in harm’s way, due to their installation and retrieval methods. And, once they are installed, they degrade rapidly under heavy traffic flow and are difficult to repair, plus crews won’t know if something has gone physically wrong with the collector until it’s retrieved. Then there’s the data they provide: road tubes have inherent limitations on data obtained, such as difficulty counting pedestrians and cyclists. Tubes are also incapable of completing turning movement counts due to the complex setup needed to measure movements and the inability to map a specific vehicle to a specific movement.
That said, road tubes are still used by many cities today to collect data for traffic studies. They are a cost-effective option, which can be the deciding factor for many cities debating alternative methods for data collection.
Video data collection
Traffic data gathered by video is non-intrusive, allowing for safe, easy, and efficient installation and always-on access to data. Video data collection provides a great breadth and depth of high-resolution traffic data that’s stored in the cloud for easy access. Also, video can be relied on to provide ground truth data, thanks to its ability to offer historical footage when needed.
While video data collection can be a more costly option, it offers added traffic study capabilities, and safe – and fast – installation and retrieval of equipment that far-outweigh the cost.
So, what’s the difference?
As indicated above, the two most obvious differences between these two methods of traffic data collection are the cost and safety considerations related to installation and retrieval of data. But, once you begin to dig in a little deeper into the two options, it becomes increasingly clear that pneumatic tubes pose additional problems that should be considered before installation.
Over-counting
For starters, road tubes often over-count vehicles, especially in areas of high congestion, or low speeds. Additionally, they are directly affected by blockage from parked cars. In fact, we recently published a case study, which among other observations, showed that blockages from delivery vehicles and police cars caused 35% fewer cars to be reported on average during these times.
Safety
The installation and retrieval of road tubes pose numerous safety hazards for technicians. That’s because technicians must physically enter the roadway to install and remove road tubes. In large cities, installation typically takes place well into the night, as vehicle congestion during the day simply does not allow for disruption. This leads to limited visibility, which increases the safety hazards faced by installation crews. In fact, the Texas Department of Transportation has gone on record to say that they are “… no longer using pneumatic tubes for vehicle counts on highway ramps due to a safety concern involving the crews installing and removing the roadside equipment.”
Equipment failure
Equipment failure is another factor working against road tubes. Breakages, communication problems, and the inability to properly secure road tubes throughout the duration of counts are all factors that affect the quality of data collected using this method. Perhaps most frustrating, collectors which become damaged or disconnected are often not discovered until units are retrieved at the end of a study.
Data quality and assurance
Typically, once data is gathered by road tubes, in-house software is used to flag problematic data for further review. But, since there is no source of ground-truth to verify the data the quality is impacted as is the ability to verify its accuracy.
Finally, waste, weather, and efficiency are also known problems associated with data collection using road tubes. If you’d like to dive deeper into any of these areas, our case study goes deeper on all of the issues inherent in this method of data collection.
Video traffic data is the clear choice
While they can be used rather effectively to provide quick spot studies or traffic counts at a small number of locations, larger studies along corridors with multiple busy intersections prove especially challenging for the humble road tube. Video traffic data collection is safer, and provides a much more efficient method for collecting the data needed to complete accurate and reliable traffic studies. It’s no wonder traffic teams are beginning to turn away from road tubes and are starting to embrace technologies like video data collection.
Learn how road tubes stack up against Miovision Scout video data collection in our case study.
