## 1 Introduction  
Transporting oversized loads is a unique type of operation that uses various abnormal vehicles, as shown in Table 1. These operations encompass both heavy or super-heavy items and oversized loads known as AILs (Abnormal Indivisible Loads). To successfully complete these complex deliveries, transport companies require the following [1, 2, 3]:  
1. During the preparation phase:
2. A fleet suitable for transporting AILs;
3. Proper transport means equipped with axle load monitoring systems, speed control systems for the route, and systems for checking their condition [4]. 4. During the organizational phase:Taking into account the terrain shape (road geometry) for the transport route, as increased complexity can cause driver fatigue, increase the likelihood of the load's center of gravity shifting, etc. ;
* Choosing the appropriate route and timing for transport, considering specific road infrastructure elements, including potential emergency parking spots, refueling stops, possible detour routes, etc. ;
* Preparing the load for transport, considering how it reacts to adverse weather conditions during the transport;
* Securing AILs to minimize the risk of it falling or the Semi-Tractor-Trailer (STT) tipping;
* Developing an incident management plan (policies, procedures, recommendations), including contingency plans for incidents such as breakdowns, fuel/oil spills, accidents, etc. * During transport operations:
* Ensuring adherence to the transport schedule;
* Identifying emerging threats to ensure the safety of all road users;
* Using necessary devices (e.g., securing, communication) during the transport of AILs. The U.S. Federal Motor Carrier Safety Administration (FMCSA) along with the National Highway Traffic Safety Administration (NHTSA) prepared the LTCCS (Large Truck Crash Causation Study) report based on a sample of nearly 1000 road accidents involving trucks that occurred from 2018 to 2020 [6]. The report indicates that over the entire study period (2010-2020), the overall number of fatal truck accidents increased by 31%, with a 3% decrease from 2019 to 2020. However, the rate increased from 0.162% to 0.177% per 100,000,000 km from 2019 to 2020. In fatal accidents, STTs with one trailer accounted for 53%, with two trailers for 3%, and with three trailers for less than 0.1% (Table 2). The analysis presented in the report shows that accidents occurred in two ways: either when the STT was the main cause (First Harmful Event, Table 3) or when it was just a factor increasing the risk of the event (Second Harmful Event, Table 4). \begin{table}
\begin{tabular}{c c c} \hline \hline
**LGV/HGV** & **Tractor Truck with One Low-Bed Trailer** & **Tractor Truck with Two Low-Bed Trailers** \\ \hline \hline Requires equipping with markings and warning lights. & Requires a Transport Execution Plan for any transport route. & Requires a Transport Execution Plan. The selected route must cover the minimum distance. \\ \hline \hline \end{tabular}
\begin{tabular}{c c} \hline \hline \multicolumn{2}{c}{Vehicle characteristics:} \\  & Speed: \\  & v \(\leq\) 65 km/h—highways & Speed: \\ Vehicle characteristics: & v \(\leq\) 56 km/h—4-lane roads & v \(\leq\) 5 km/h (remote control), \\ Axle load—normative & v \(\leq\) 48 km/h—2-lane roads & v \(\leq\) 25 km/h (manual control) \\ Width up to 3.2 m & Load characteristics: & Load characteristics: \\ Length up to 15 m & Width \(\leq\) 3.2 m & Width 3.2–6.5 m \\ Height up to 4.3 m & Length \(\leq\) 18.75 m & Length \(\geq\) 18.75 m \\  & Height \(\leq\) 4.5 m & Height \(\geq\) 4.5 m \\  & Mass \(\leq\) 60 t axle load: \(\leq\)15 t & AIL mass \(\leq\) 5000 t axle load: \(\leq\)15 t data 1 \\ \hline \hline \end{tabular} \({}^{1}\) Own elaboration based on [5]. Source: [[https://stock.adobe.com/](https://stock.adobe.com/)]([https://stock.adobe.com/](https://stock.adobe.com/)) (accessed on 7 August 2024).  
\end{table} 
Table 1: Types of vehicles used for transporting AILs.