# A Comparative Study of the Availability of Electric Buses in the Public Transport System
## 3 Experimental Procedure  
### Test Facilities and Conditions  
The research was carried out at the Municipal Transport Company in Lublin using samples of buses of two makes, SOLARIS URBINO12 ELECTRIC with electric drive and URSUS BUS CF 12 LFD with internal diesel drive, with 18 vehicles of each make. All the vehicles tested were new units with no previous operating mileage. The technical characteristics of the vehicles tested are shown in Table 1.  
The tests were conducted under standard operating conditions in the Municipal Transport Company in Lublin. The tests were conducted over the calendar time period from 2021 to 2024, with a total of 33 months of bus use.  
The studied buses operated on regular public transport routes in urban traffic. The average daily mileage was about 238 km for electric vehicles and 243 km for diesel vehicles; the deviation of the extreme values did not exceed 85 km. The average monthly mileage was 4860 km for electric buses and 4920 km for diesel buses.  
Any of the studied vehicles that were technically efficient could be sent to serve one of the operated lines. The lines were operated in a two-shift, all-day operating pattern or  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **URSUS BUS CS 12 LFD** & **SOLARISURBINO12 ELECTRIC** \\ \hline Bus type & two-axle, low-floor, urban \\ Length [m] & 12.0 & 12.0 \\ Door layout & 2 \(-\)2 \(-\)2 \(-\)2 & 2 \(-\)2 \(-\)2 \\ Total number of seats & 105 & 81 \\ Number of seating places & 28 & 29 \\ Battery capacity [KWh] & not applicable & 120 \\ Charging power [KWh] & not applicable & Up to 450 \\ Engine characteristic & 6 cylinders, 6.7 L, 221 kW & Two asynchronous motors in rear drive axle, maksimum total power of \\ Maximum permissible weight [kg] & 19,000 & 18,745 \\ Exhaust emissions standard & Euro VI & not applicable \\ \hline \end{tabular}
\end{table}
Table 1: Technical and operational parameters of tested buses.  
only during the peak period. During full service on all lines, a bus could also remain at the depot in a state of technical availability as a reserve vehicle.  
Damage incurred or discovered during the run was a signal to the driver to stop transport work and take the bus to the depot. Each repair was carried out, depending on the time of departure, either immediately or starting from the next mechanic's shift.  
In this study, the source data base was the company's vehicle technical availability reports. The availability reports contained a record of the operating states of each vehicle, broken down by the next day of each month. Due to limited access to data, a vehicle was considered unavailable when a failure occurred on a given day. If a vehicle performed tasks without faults during a shift (two-shift, all-day, or peak period), it was counted as an unavailable vehicle. Two states were considered: the availability state, denoted as '1', and the unavailability state, denoted as '0' (Figure 2). The same indicator defined in Equation (1) was used to calculate the technical availability index of diesel and electric vehicles.  
The readiness reports were prepared by the carrier using the integrated IT management system MUNICOM TARAN. At the end of each work shift, as part of the use of the aforementioned system, the technical support (service) employee monitored the vehicle's operational status. The data recorded in the system were sent to dispatchers at the company's traffic headquarters. For a faulty vehicle, the system prevented issuing a road card on the next working day, which meant stopping the vehicle at the service and repair base. The aforementioned technical readiness reports were the basis for warranty settlements with individual vehicle manufacturers, as well as for meeting the implementation of the transport task plan.  
In a later section of the article, abbreviated names of the tested vehicles are introduced according to the type of drive, and it is assumed that Ursus buses will be labelled as 'diesel' and Solaris buses as 'electric'.