This practice was the first tender for purchase of electric buses and charging stations for public transport ever by Bulgarian authorities.
In order to develop the technical specifications of the tender, the concept for development of the urban transport system in Sofia city and the needs of the operator itself were analyzed. One of the main factors taken into account was the quality of the service and the possibility of the new electric buses to be used on other lines in the network in case of accidents and failures.
Due to the lack of experience with such type of technologies in Bulgaria, a detailed study was carried out. Different models of electric buses were tested on different lines of the city public transport network for 6 months.
The analysis of the needed battery capacity was made, based on the assumption that the required minimum daily route is 320 km under normal operating conditions. The charging should be within 5 hours over night.
Technical specifications:
Two axle buses with length of 12 m;
Number of passengers -min. 70 (seated and standing without driver);
Battery capacity -min. 280 kWh;
Heating / cooling power -min. 30 kW;
Engine power -min. 320 kW;
Charging stations -5 pcs. with min power 120 kW (double) and 10 pcs. with min power 60 kW (single);
Award criteria:
Energy costs -15%
Warranty conditions -5%
Technical characteristics (torque, power, mileage) -25%
Total value (excluding leasing cost) -45%
Lease cost -10%

Resources needed

Total leasing cost: 11 350 224 EUR (excl. VAT), covering:
• Cost of the equipment: 8 527 860 EUR
• Lease fee: 2 822 384 EUR

Evidence of success

The new electric buses lead to an estimated reduction of CO2 emissions by 700 t/yr compared to the existing diesel buses. Compared to EURO 6 diesel buses, the new electric buses generate 330 tCO2/yr less. Other benefits from the public procurement are the avoidance of harmful NOx and dust, as the new vehicles has zero tailpipe emissions.
Additionally, the calculated fuel savings equate to financial savings of about 576 000 EUR per year (depending on the change of fuel and electricity prices).

Difficulties encountered

Only one bidder submitted a proposal for this specific tender. Based on discussions with the procurers and technical experts there are two main reasons for this:
The required daily route of 320 km is sometimes hard to be reached by some manufactures;
The leasing of such an amount is frightening

Potential for learning or transfer

The overall concept for the development of public transport in each specific region must be taken into account. The type of bus technology can be determined by the suppliers based on a detailed needs analysis. Also, continuous testing of different buses in normal conditions (if possible) makes the development of the technical specification in the tender documentation easier. The implementation of these steps allows good practice to be transferred to each region / country.

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Main institution
Stolichen Avtotrasnsport EAD/ Sofia Municipality
Югозападен, Bulgaria (България)
Start Date
January 2017
End Date
January 2018


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