## 2 State of the Art
### Automated Counting  
Common technologies for counting micromobility vehicles and pedestrians are pneumatic tubes, piezoelectrics, induction loops, infrared, radar, and cameras. A recent investigation by North Carolina State University [3] reported the use of commercially available systems based on these principles. Table 2 provides an overview of these technologies, summarizes their advantages and disadvantages, and gives values for the average accuracy achieved, as stated by [3; 5; 6]. Pneumatic tubes and piezo cables require contact with the vehicle and need to be surface-mounted. They can detect wheels very reliably, but pedestrians may walk over the sensors without making contact. This can be compensated for in part by deploying these sensors in the form of pressure-sensitive mats. The deformation of the sensor required to \begin{table}
\begin{tabular}{c c c c c c c c c} \hline Duration & 1 h & 2 h & 3 h & 9 h & 12 h & 24 h & 1 w & 2 w & 4 w \\ \hline Average error & 48\% & 46\% & 40\% & 34\% & 35\% & 38\% & 22\% & 19\% & 15\% \\ \hline \end{tabular}
\end{table} 
Table 1: Average annual daily bicycle estimation error according to [4]. generate a signal can cause a high amount of wear on the sensors when used in mixed traffic. The surface mounting can also cause hazards for pedestrians and vehicles with small wheels such as kickscooters, skateboards, and inline skates. When the tubes and cables are mounted incorrectly or come loose because of wear, small wheels can become stuck and cause tripping. Additionally, these systems can be understood as obstacles, causing people to slow down or avoid contact and therefore have an unintended influence on the obtained traffic data. Induction loops are not surface-mounted, not exposed to wear, or able to come loose. The in-ground installation requires opening the ground or making incisions. This requires time and heavy tools and destroys the sealed surface. Special induction systems can be surface-mounted in a similar way to the piezo cables but then suffer from the same shortcomings. In addition, the induction loop can only detect ferromagnetic objects. Thus, pedestrians cannot be detected. Using the concepts of pattern matching as described by [PERSON] et al. [7] allows distinction into different classes. Radar can be placed on the side of the road, and if a suitable mounting spot is available, then no construction is necessary. Objects in front of the sensor may cast a shadow and obstruct objects in the background, making distinctions and classification difficult in groups. Spot infrared (IR) systems come with similar advantages and disadvantages to radar but with much lower power consumption. Automated systems utilizing cameras are the newest technology on this list. They only became feasible with the latest advances in modern image processing. They allow a good distinction between different vehicle classes, and they can be mounted to existing structures while requiring very little set-up time. The shortcomings of camera-based counting systems are the huge amount of data that cameras generate. This leads to large memory or bandwidth requirements to store or transmit the raw data or large requirements for processing power if the processing is performed locally. In both cases, good ambient lighting is required, and the accuracy can vary significantly depending on the location [3; 6]. In addition, cameras can pose privacy problems if the image data are stored or transmitted, potentially leading to acceptance problems for the public.