Comparison of External Monetary Environmental Impacts of Regional Railway and Road Passenger Transport in the Context of the Potential Discontinuation of Regional Railway Services in Slovakia

Abstract

The aim of the presented article is the comparison of external monetary environmental impacts generated by railway and road transport in Slovakia region. The Kralovany–Trstena regional line located in the northern Slovakia was selected. The monetary impacts of environmental pollution from transport on this line were analysed. Various pollutants were selected for the assessment from exhaust gases, such as fine particulate matter PM_2.5, nitrogen oxides (NO_x), sulphur dioxide (SO₂), non-methane volatile organic compounds (NMVOC), and ammonia (NH₃). The Cost–Benefit Analysis methodology was applied for the calculation of monetary impacts. The results point out that the usage of diesel multiple units on the given line has a significant impact on the monetary impacts of pollutant emissions.

1. Introduction

Transport is an integral component of modern society, yet it is simultaneously one of the major contributors to environmental pollution. Both road and rail transport play essential roles in passenger mobility, but their environmental impacts differ substantially. This article focuses on comparing the monetary effects of non-market impacts and their valuation. Although non-market impacts can typically be identified relatively easily, the challenge lies in their quantification and monetisation. Quantification refers to expressing the magnitude of an impact—for example, how many users utilise transport services and what time or fuel savings they achieve, how many traffic accidents are likely to occur and how severe they may be, how many tonnes of individual pollutants are released into the atmosphere, and so forth. These data are often difficult to obtain; in the context of transport projects, relevant sources usually include transport models as well as various databases and projections. After quantifying non-market impacts, it is necessary to express them in monetary terms. The most commonly used approach for valuing non-market impacts is the concept of the consumer’s marginal willingness to pay. Marginal willingness to pay measures the maximum monetary amount that individuals (consumers) are willing to pay for a specific outcome they perceive as desirable. To estimate how much consumers are willing to pay, various techniques are applied, such as stated preference methods, revealed preference methods, or benefit transfer methods—each based on empirical surveys of consumer behaviour [1]. Several alternative approaches exist for valuing non-market impacts. One such alternative is the avoided-cost method, which estimates the expenses that would need to be incurred to obtain an equivalent outcome from another source [2,3,4]. Since the necessary empirical surveys to determine consumer willingness to pay have not yet been conducted under Slovak conditions, the valuation of most impacts relies on prices derived from or adopted from relevant international sources [5,6,7]. Among the major non-market impacts generated by transport are emissions of air pollutants, which form the basis of the comparison presented in this article.

The Kralovany–Trstena regional line located in the northern Slovakia Orava region was selected, because it was considered inefficient by the Value for Money Unit of the Slovak Republic. In 2021, the Value for Money Unit did not recommend the purchase of new diesel multiple units for this line [8], and in 2021, at the meeting of the Transport and Construction Commission of the Slovak Republic, a proposal was presented to minimise operating costs on this line with a gradual phase-out of service.

The selected railway line is characterised by a low average operating speed (31 km/h), caused by operational constraints. The line includes sections running through cuttings with steep rock faces at multiple locations. Transport demand is also low, specifically fewer than 50 passengers per train. The national rail operator, Železničná spoločnosť Slovensko, disagreed with the recommendations in both 2020 and 2021 and initicted investments into the renewal of the rolling stock, arguing that rail transport is more environmentally friendly than road transport. This standpoint, however, did not take into account the fact that the trains operate at an average occupancy rate of only 25% and that the line is not electrified.

Various pollutants from exhaust gases were selected for the assessment, such as fine particulate matter PM_2.5 and nitrogen oxides (NO_x) produced as by-products of combustion engines; sulphur dioxide (SO₂), present in the exhaust gases of internal combustion engines; non-methane volatile organic compounds (NMVOC), which arise from fuel combustion and vehicle operation; and ammonia (NH₃). For the calculation of monetary impacts, the Cost–Benefit Analysis methodology was applied, as described in this article for the required computations.

2. Methodology for Calculating the Monetary Impacts of Environmental Change

Environmental pollution represents one of the external, non-monetary costs of transport, borne primarily by third parties—that is, individuals (or, more broadly, the environment) in the affected area, rather than direct users of transport services. While pedestrian or cycling transport can be assumed to impose (almost) zero such costs, in other transport modes that rely on the combustion of hydrocarbon fuels, these costs are substantial. Different modes of transport may therefore result in positive or negative changes in the level of harmful emissions released into the environment [1].

In this context, environmental pollution refers primarily to air pollutants produced by the combustion of fuels—i.e., exhaust gases. In our calculations, the following pollutants are considered:

• Particulate matter PM_2.5;
• Nitrogen oxides NO_X;
• Sulphur dioxide SO₂;
• Non-methane volatile organic compounds NMVOC;
• Ammonia NH₃ [1].

Since the assessment focuses exclusively on exhaust emissions, the calculation of emissions from road vehicles must be based on fuel and energy consumption data. These depend on several factors, including average vehicle speeds (50 km/h in urban areas, 90 km/h outside urban areas), annual vehicle-kilometres travelled, and the composition of the passenger car fleet. A segment of a conservative forecast of the expected evolution of the vehicle fleet composition is presented in

Table 1. Forecast of the expected evolution of the vehicle fleet composition.

Composition of Passenger Cars by Type of Propulsion (%)
Year	Petrol	Diesel	Electric
2025	54.27	44.40	1.33
2026	53.66	43.91	2.43
2027	53.08	43.43	3.49
2028	52.51	42.96	4.53
2029	51.96	42.51	5.53
2030	51.43	42.08	6.50
2031	50.60	41.40	8.00
2032	49.53	40.53	9.94
2033	48.22	39.46	12.32
2034	46.74	38.25	15.01
2035	44.83	36.68	18.50

[9]. The orange color stands for road transport; the green color stands for rail transport; the blue color stands for economical variable values. This applies for the whole article.

This trend is nevertheless considered relevant given the declared objectives of the European Union in the field of reducing environmental pollution and greenhouse gas emissions, as well as the ongoing transformation of the automotive industry [10].

Table 2. Average fuel and energy consumption by vehicle category and speed.

Average Fuel and Energy Consumption
Vehicle Category	Unit	Speed (km/h)
		50	90
Passenger cars (petrol)	L/km	0.066	0.059
Passenger cars (diesel)	L/km	0.057	0.055
Passenger cars (electric)	kWh/km	0.138	0.177
Buses (diesel)	L/km	0.262	0.238

specifies the average fuel and energy consumption as a function of vehicle category and speed [6]. For the calculations, legally permitted speed limits within the territory of the Slovak Republic were applied: 50 km/h in urban areas and 90 km/h in non-urban areas. In the model scenario, the line does not include motorway sections, where the maximum permitted speed is 130 km/h [1].

To calculate the total fuel consumption, it is necessary to determine the unit prices of the respective energy sources. Fuel prices fluctuate frequently due to numerous external factors; therefore, the average prices of diesel and petrol for the period 2015–2022 from the database of the Statistical Office of the Slovak Republic were used in the calculations. These prices were subsequently adjusted for relevant taxes to ensure their applicability. The price of electricity was determined as a weighted average of charging costs across different charging modes (home vs. charging station; slow vs. fast charging), also adjusted for taxes. The resulting recommended prices are as follows [1]:

• Petrol: 0.603 EUR/L;
• Diesel: 0.653 EUR/L;
• Electricity: 0.02 EUR/kWh.

Fuel consumption of railway vehicles (traction diesel and traction electricity) for selected rolling stock types is presented in

Table 3. Average consumption of traction diesel and electric energy for various rail vehicle class.

Average Consumption of Traction
Power Type	Unit	Rail Vehicle Class
		861	840	813	812	661	BEMU
Traction diesel	L/train-km	1.8051	0.6318	0.5871	0.4810	7.0800	-
Electric energy	kWh/train-km	-	-	-	-	-	7.0800

. The average consumption of traction diesel/traction energy was provided by Železničná spoločnosť Slovensko a.s., Bratislava, Slovakia.

Using the calculated values, fuel consumption is first obtained in volumetric units. For further calculations, it is necessary to convert this consumption into mass units based on the density of the individual fuels, as follows [1]:

• Petrol: 0.72 kg/L,
• Diesel: 0.82 kg/L.

If fuel consumption is known, it is possible to determine the total quantity of emitted pollutants using so-called emission factors. Since the societal unit costs are expressed in kilograms, the corresponding quantities must likewise be expressed in kilograms. The emission factor specifies the amount of harmful substances released into the atmosphere per kilogram of burned fuel. For road vehicles, several data sources are available for this purpose. Standardised emission factors are typically established with respect to the characteristic vehicle fleet of a given country or region and for different vehicle categories. For the purposes of this article, data provided by the European Environment Agency (EEA) for the year 2019 may be used, as summarised in

Table 4. Emissions factors of pollutants for road vehicles.

Emission Factors of Pollutants for Road Vehicles (g/kg)
Vehicle Category	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3
Passenger cars (petrol)	0.030	8.730	0.020	10.050	1.106
Passenger cars (diesel)	1.100	12.960	0.020	0.700	0.065
Light commercial vehicles (diesel)	1.520	14.910	0.020	1.540	0.038
Medium-duty trucks (diesel)	0.940	33.370	0.020	1.920	0.013
Heavy-duty trucks (diesel	0.940	33.370	0.020	1.920	0.013
Buses (diesel)	0.940	33.370	0.020	1.920	0.013

for road vehicles and

Table 5. Emission factors of pollutants for railway vehicles.

Emission Factors of Pollutants for Railway Vehicles (g/kg)
Vehicle Category	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3
Line locomotive	1.100	63.000	0.020	4.800	10.000
Diesel multiple unit	1.000	39.900	0.020	4.700	10.000

for railway vehicles [11,12].

In

Table 6. Prediction of costs of pollutant emissions from transport.

Costs of Pollutant Emissions from Transport (EUR/kg)
Year	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3
2025	93.1	23.2	15.9	1.1	38.5
2026	95.2	23.7	16.3	1.2	39.4
2027	96.8	24.1	16.6	1.2	40.0
2028	98.1	24.4	16.8	1.2	40.6
2029	99.5	24.8	17.0	1.2	41.2
2030	100.8	25.1	17.3	1.2	41.7
2031	102.0	25.4	17.5	1.3	42.2
2032	103.3	25.7	17.7	1.3	42.7
2033	104.5	26.1	17.9	1.3	43.2
2034	105.8	26.4	18.1	1.3	43.8
2035	107.0	26.7	18.3	1.3	44.3

, a selected segment of the unit costs of pollutant emissions from transport (EUR/kg) is presented [13]. The listed unit values have been time-adjusted according to real GDP growth using an elasticity of 0.8 (for the Slovak Republic).

3. Description of the Model Case

For the comparison of external monetary environmental impacts generated by railway and road transport in the Slovak Republic, the Kralovany–Trstena line was selected. This line is located in the Orava region. For the purpose of comparison and construction of the transport model, the characteristics were divided into the transport (operational) characteristics and the carriage (transport-demand) characteristics. The transport characteristics focus on the operational properties of the line—specifically the characteristics of the railway line, road infrastructure, vehicles, railway stations, and stops. The carriage characteristics analyse quantitative indicators.

Figure 1 shows a map of the Kralovany–Trstena line [14], displaying:

• The railway line (thin black line),
• The road connection (thick blue line).

From the map, it is clear that the railway line runs parallel to the road.

3.1. Rail Transport

From the perspective of rail transport, the Kralovany–Trstena line is operated on railway line no. 181 with a total length of just under 57 km. The transit time is 109 min, with an average travel speed of 31 km/h. Transport is provided by diesel multiple units of class 813/913, intended for operation on non-electrified regional lines. The capacity of the unit is 83 seated passengers and 120 standing passengers [15].

The line has a standard gauge of 1435 mm. Within the line, eight railway stations and eleven stops are served, with two stops equipped with passing loops enabling train crossings. A summarised overview of the railway operation parameters is shown in

Table 7. Characteristics of the Kralovany–Trstena railway.

Kralovany–Trstena Railway Parameters
Route number	181
Route length	57	km
Travel time	109	min
Average travel speed	31	km/h
Track gauge	1435	mm
Maximum gradient	15	‰
Traction power supply	-	none
Number of railway stations	8	stations
Number of railway stops	11	stops
Number of stops with passing loops	2	passing loops

[16].

3.2. Road Transport

From the perspective of road transport, the Kralovany–Trstena route is operated by bus services, with the possibility of using individual automobile transport. The connection between these towns follows first-class roads I/70 (Dolný Kubín district) and I/59 (Tvrdošín district), which form part of the internationally significant route E77. A summary of the characteristics of the road connection is presented in

Table 8. Characteristics of the Kralovany–Trstena road.

Kralovany–Trstena Road Parameters
Road section number (Dolný Kubín district)	I/70
Road section number (Tvrdošín district)	I/59
Road classification (I/70; I/59)	1-st	class
Distance by car	54	km
Travel time by car	61	min
Average travel speed by car	53	km/h
Number of pedestrian crossings	49	crossings
Number of signal-controlled intersections	0	traffic light controlled intersection
Number of railway level crossings	4	crossings
Distance by bus	72	km
Travel time by bus	99	min
Average travel speed by bus	44	km/h
Number of bus stops	35	stops

.

The total distance by car is 54 km, with a travel time of 61 min and an average travel speed of 53 km/h. Along this route, there are four railway level crossings and 49 pedestrian crossings [14].

Bus transport covers a route length of 72 km, with a travel time of 99 min and an average speed of 44 km/h. There are 35 bus stops along the route. Bus services are operated by ARRIVA Liorbus, a.s., Ruzomberok, Slovakia [17].

3.3. Transport Demand Characteristics

Rail passenger transport on line number 181, according to statistics of the Ministry of Transport, transports 1097 persons per day [18]. Considering that the line is served daily by 25 train connections [19], the average occupancy of one train is 44 passengers. This low average occupancy of diesel multiple units, whose capacity is 200 persons, together with high costs, results in this line being considered inefficient and included among the lines where the discontinuation of regional passenger rail transport is being considered. For the given line, a transport forecast was prepared based on a multi-criteria analysis.

Table 9. Forecast of the development of passengers transported by rail until 2035.

Number of Passengers Transported by Rail
Year	Total	Fare Type
		Free	Discounted	Full
2025	400,405	198,601	11,571	190,233
2026	406,349	201,550	11,742	193,057
2027	412,381	204,541	11,917	195,923
2028	418,502	207,577	12,094	198,831
2029	424,714	210,659	12,273	201,782
2030	431,019	213,786	12,455	204,778
2031	437,417	216,959	12,641	207,817
2032	443,910	220,180	12,828	210,902
2033	450,500	223,448	13,019	214,033
2034	457,187	226,765	13,212	217,210
2035	463,974	230,132	13,407	220,435

presents the results of the forecast of the development of passengers transported by rail until 2035 and the distribution of passengers according to the fare level. Passengers are divided into free-fare passengers with a 0% fare payment, discounted-fare passengers with a 40% fare payment, and full-fare passengers with a 100% fare payment. The discounted-fare group consists of passengers with a disability card (2.88%). The full-fare group consists of adult passengers without entitlement to any discount (47.51%). The free-fare group (49.60%) consists of children, pupils, students, and pensioners.

Passengers using rail transport had to be reassigned to an alternative mode of transport. Based on studies [20,21,22,23], hypotheses were formulated. To verify this hypothesis, the authors conducted a simple questionnaire survey in which regular train passengers were asked which mode of transport they would prefer if regional rail services on the analysed section were discontinued. The survey was carried out during peak traffic periods in the morning and afternoon over three days—Monday, Wednesday, and Friday. Irregular passengers did not participate in the survey and did not express their views on the issue. The results of the empirical survey determined the preferences of rail passengers as follows:

• Free-fare passengers will switch to bus transport in the event of the discontinuation of rail transport,
• Passengers with a disability card as well as passengers without any fare discount would prefer individual automobile transport after the discontinuation of rail transport.

4. Determination of the External Monetary Impacts of Environmental Pollution from Rail Passenger Transport on the Kralovany–Trstena Line

In comparing external monetary impacts, we will first address rail transport in the case that the regional line is not discontinued. The average consumption is presented in Table 3. On the given line, transport is provided by the diesel multiple unit 813/913, therefore the calculations will use the average consumption of 0.5871 L/train-km. To make this calculation possible, the transport performance expressed in persons must be converted into transport performance expressed in train-kilometres. This conversion is presented in

Table 10. Development of train-kilometres on the Kralovany–Trstena line forecast.

Transport Performance
Year	(Number of Persons)	(Train-km)
2025	400,405	518,757
2026	406,349	526,452
2027	412,381	534,261
2028	418,502	542,184
2029	424,714	550,221
2030	431,019	558,372
2031	437,417	566,694
2032	443,910	575,073
2033	450,500	583,623
2034	457,187	592,287
2035	463,974	601,065

, where the average occupancy of the train is 44 persons (rounded upwards) and the transport distance is 57 km. The train must operate over the entire distance, which means that we will consider the full distance also in the calculations.

The next step in calculating the monetary impacts is the calculation of the consumed diesel fuel for the individual years. By this calculation we obtain the total volume of diesel consumed in volumetric units (litres). For the following calculations it is necessary to convert this volumetric unit into a mass unit according to the density of diesel fuel, which is 0.82 kg/L.

Table 11. Consumption of diesel fuel on the Kralovany–Trstena line forecast.

Consumption of Traction Diesel Fuel
Year	(L)	(kg)
2025	304,581.52	249,756.85
2026	309,099.54	253,461.63
2027	313,684.50	257,221.29
2028	318,336.39	261,035.84
2029	323,055.21	264,905.27
2030	327,840.96	268,829.59
2031	332,727.12	272,836.24
2032	337,646.74	276,870.33
2033	342,666.76	280,986.75
2034	347,753.72	285,158.05
2035	352,907.61	289,384.24

presents the results of the calculation both in volumetric units and converted into mass units based on the transport performance for the individual years.

If the diesel fuel consumption is calculated in kilograms, it is then possible, according to the emission factors, to calculate the total amount of emitted pollutants in kilograms (the unit costs of pollutants are expressed per kilogram). In the calculation of pollutant emissions, Table 5 is used, specifically the row for diesel multiple units.

Table 12. Amount of emitted pollutants per year of a diesel multiple unit prediction.

Amount of Emitted Pollutants (kg)
Year	Pollutant Type
	PM2.5	NOx	SO2	NMVOC	NH3
2025	249.76	9965.30	5.00	1173.86	2497.57
2026	253.46	10,113.12	5.07	1191.27	2534.62
2027	257.22	10,263.13	5.14	1208.94	2572.21
2028	261.04	10,415.33	5.22	1226.87	2610.36
2029	264.91	10,569.72	5.30	1245.05	2649.05
2030	268.83	10,726.30	5.38	1263.50	2688.30
2031	272.84	10,886.17	5.46	1282.33	2728.36
2032	276.87	11,047.13	5.54	1301.29	2768.70
2033	280.99	11,211.37	5.62	1320.64	2809.87
2034	285.16	11,377.81	5.70	1340.24	2851.58
2035	289.38	11,546.43	5.79	1360.11	2893.84

presents the results of the calculations of emitted pollutants already expressed in kilograms for the monitored Kralovany–Trstena line.

After quantifying the physical units of pollutant emissions, i.e., quantifying the amount, it is possible to proceed to the valuation of these pollutant units in monetary units in EUR. For the valuation, Table 6 is used and the results are presented in

Table 13. External monetary impacts of environmental pollution from rail passenger transport prediction.

Costs of Pollutants in Rail Transport (EUR)
Year	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3	Total
2025	23,244.87	231,095.27	79.62	1314.72	96,181.36	351,915.84
2026	24,116.87	239,782.05	82.63	1369.96	99,787.84	365,139.36
2027	24,886.16	247,444.05	85.24	1414.46	102,965.68	376,795.60
2028	25,599.78	254,550.67	87.71	1459.97	105,902.24	387,600.37
2029	26,352.78	262,023.37	90.28	1506.52	109,008.52	398,981.46
2030	27,084.58	269,337.41	92.80	1554.10	112,048.17	410,117.07
2031	27,840.21	276,835.20	95.38	1602.91	115,164.18	421,537.88
2032	28,589.63	284,353.03	97.96	1652.64	118,279.00	432,972.26
2033	29,363.12	292,056.22	100.59	1703.62	121,470.57	444,694.13
2034	30,155.46	299,918.97	103.28	1755.72	124,756.65	456,690.08
2035	30,969.90	308,058.78	106.09	1808.94	128,139.34	469,083.06

.

In Table 13, the results of the monetary impacts of environmental pollution from rail transport indicate that the valuation of pollution increases each year as the transport performance increases. For the purposes of this article, it is also necessary to calculate the monetary impacts of environmental pollution from road transport, specifically bus transport and individual automobile transport. The transport performance of rail transport will be redistributed according to customer preferences, which were determined by the empirical survey.

5. Determination of the External Monetary Impacts of Environmental Pollution from Road Passenger Transport on the Kralovany–Trstena Route

As stated above, in order to make a comparison of the monetary impacts of environmental pollution from rail and road transport possible, it is necessary to quantify the monetary impacts for road transport. In the calculations we will consider the same transport performance as in rail transport, only the passengers will be redistributed according to preferences as follows: free-fare passengers will be transferred to bus transport, discounted-fare and full-fare passengers to individual automobile transport. The distribution of passengers is shown in

Table 14. Preferential transfer of passengers from rail transport prediction.

Passenger Transferred from Rail Transport (Persons)
Year	Transfer to Bus Transport	Transfer to Individual Car Transport
2025	198,601	201,804
2026	201,550	204,799
2027	204,541	207,840
2028	207,577	210,925
2029	210,659	214,055
2030	213,786	217,233
2031	216,959	220,458
2032	220,180	223,730
2033	223,448	227,052
2034	226,765	230,422
2035	230,132	233,842

.

As in the calculations for rail transport, it is also necessary here to convert the transport performance in persons into transport performance in vehicles and subsequently vehicle-kilometres in bus transport. In the calculations, the recommended average bus occupancy of 22 passengers and 1.5 passengers per automobile will be used, and the distances in bus transport of 72 km and in individual automobile transport of 54 km (Table 8). In the case of individual automobile transport, it is necessary to divide the transport performance according to the propulsion category into petrol, diesel, and electric vehicles (according to Table 1).

Table 15. Transport performance of passengers transferred from rail to road transport prediction.

Transport Performance (Vehicle km)
Year	Bus Transport	Individual Car Transport
		Petrol Vehicles	Diesel Vehicles	Electric Vehicles
2025	650,016.00	3,942,685.11	3,225,635.14	96,623.76
2026	659,664.00	3,956,234.82	3,237,388.58	179,158.60
2027	669,456.00	3,971,572.99	3,249,536.83	261,130.18
2028	679,392.00	3,987,251.28	3,262,089.41	343,977.31
2029	689,472.00	4,004,045.91	3,275,827.40	426,142.68
2030	699,696.00	4,022,025.55	3,290,819.27	508,325.22
2031	710,064.00	4,015,862.93	3,285,706.03	634,919.04
2032	720,648.00	3,989,302.71	3,264,414.27	800,599.01
2033	731,304.00	3,941,441.08	3,225,409.89	1,007,021.03
2034	742,176.00	3,877,181.15	3,172,917.83	1,245,111.02
2035	753,192.00	3,773,937.34	3,087,843.44	1,557,391.05

presents the transport performance of passengers transferred from rail to road transport in vehicle-kilometres.

From the table, despite the increasing number of passengers, the transport performance in individual automobile transport decreases in the petrol and diesel vehicle categories, since an increasing number of electric vehicles is expected. In the case of electric vehicles, zero emissions are assumed; therefore, this performance will not be considered further in the calculations [1].

The next step, as in the calculations for rail transport, is to determine the total amount of consumed fuels. In the calculations we will use the data from Table 2; however, the electric vehicle category will no longer be included, since this type of propulsion is considered pollutant-free (exhaust gases emission free). It is necessary to divide the route into an urban section, where an average speed of 50 km/h will be used, and a non-urban section, where the average fuel consumption corresponding to a speed of 90 km/h will be applied.

Table 16. Distribution of road infrastructure usage for individual car transportation (ICT) and bus transportation (BT).

Distribution of Road Infrastructure Usage (%)
Urban Area of Town		Urban Area of Municipality		Non-Urban Area
ICT	BT	ICT	BT	ICT	BT
26.57	31.96	27.39	28.42	46.04	39.63

presents the percentage distribution of the road infrastructure into non-urban area, urban area of a municipality, and urban area of a town for bus transport and individual automobile transport.

In calculating the consumed fuels we draw on Table 15 (transport performance), Table 16 (distribution of road infrastructure), and Table 2 (average fuel consumption depending on vehicle category and speed in L/km for petrol and diesel).

Table 17. Fuel consumption prediction according to vehicle category and the type of road infrastructure.

Fuel Consumption Prediction (L)
Year	Urban Area of Town			Urban Area of Municipality			Non-Urban Area
	Diesel Bus	Petrol Car	Diesel Car	Diesel Bus	Petrol Car	Diesel Car	Diesel Bus	Petrol Car	Diesel Car
2025	54,429.22	69,139.71	48,851.92	48,400.45	71,273.50	50,359.58	61,309.12	107,097.52	81,679.53
2026	55,237.10	69,377.33	49,029.93	49,118.85	71,518.44	50,543.08	62,219.11	107,465.58	81,977.15
2027	56,057.03	69,646.30	49,213.91	49,847.96	71,795.71	50,732.74	63,142.69	107,882.22	82,284.77
2028	56,889.02	69,921.24	49,404.02	50,587.80	72,079.14	50,928.72	64,079.85	108,308.10	82,602.63
2029	57,733.08	70,215.75	49,612.08	51,338.36	72,382.74	51,143.20	65,030.59	108,764.30	82,950.50
2030	58,589.18	70,531.04	49,839.13	52,099.64	72,707.76	51,377.26	65,994.91	109,252.69	83,330.13
2031	59,457.35	70,422.98	49,761.69	52,871.65	72,596.36	51,297.43	66,972.81	109,085.29	83,200.65
2032	60,343.60	69,957.21	49,439.23	53,659.74	72,116.22	50,965.01	67,971.09	108,363.82	82,661.50
2033	61,235.89	69,117.90	48,848.51	54,453.19	71,251.01	50,356.07	68,976.15	107,063.73	81,673.83
2034	62,146.26	67,991.02	48,053.52	55,262.72	70,089.35	49,536.54	70,001.60	105,318.20	80,344.63
2035	63,068.68	66,180.52	46,765.08	56,082.98	68,222.97	48,208.34	71,040.62	102,513.72	78,190.37

presents the fuel consumption in volumetric units (L) according to vehicle category—bus, petrol car, and diesel car—and according to the type of road infrastructure.

For better clarity and easier conversion of volumetric units (L) into mass units (kg),

Table 18. Fuel consumption prediction in road transport for various fuels and vehicle types.

Fuel Consumption Prediction
Year	(L)			(kg)
	Diesel Buses	Petrol Cars	Diesel Cars	Diesel Buses	Petrol Cars	Diesel Cars
2025	164,138.79	247,510.73	180,891.04	134,593.81	178,207.73	148,330.65
2026	166,575.05	248,361.34	181,550.16	136,591.55	178,820.17	148,871.13
2027	169,047.68	249,324.23	182,231.43	138,619.10	179,513.45	149,429.77
2028	171,556.67	250,308.47	182,935.36	140,676.47	180,222.10	150,007.00
2029	174,102.02	251,362.79	183,705.78	142,763.66	180,981.21	150,638.74
2030	176,683.74	252,491.50	184,546.51	144,880.66	181,793.88	151,328.14
2031	179,301.81	252,104.63	184,259.77	147,027.48	181,515.33	151,093.01
2032	181,974.43	250,437.25	183,065.74	149,219.03	180,314.82	150,113.91
2033	184,665.23	247,432.63	180,878.41	151,425.49	178,151.50	148,320.29
2034	187,410.57	243,398.58	177,934.69	153,676.67	175,246.98	145,906.45
2035	190,192.28	236,917.22	173,163.79	155,957.67	170,580.40	141,994.31

presents the total fuel consumption only for petrol and diesel. Subsequently, the fuel consumption is presented also in mass units (kg) according to the density of the individual fuels, namely petrol 0.72 kg/L and diesel 0.82 kg/L.

If the fuel consumption is calculated in mass units, it is possible, according to the emission factors, to calculate the total amount of emitted pollutants in kilograms. In the calculation of pollutant emissions, Table 4 and Table 18 are used.

Table 19. Amount of partial pollutants emitted from road vehicles according to vehicle category prediction.

Amount of Partial Pollutants (kg)
Year	Vehicle Category	Pollutant Type
		PM2.5	NOX	SO2	NMVOC	NH3
2025	bus	126.52	4491.40	2.69	258.42	1.75
	diesel car	163.16	1922.37	2.97	103.83	9.64
	petrol car	5.35	1555.75	3.56	1790.99	197.10
2026	bus	128.40	4558.06	2.73	262.26	1.78
	diesel car	163.76	1929.37	2.98	104.21	9.68
	petrol car	5.36	1561.10	3.58	1797.14	197.78
2027	bus	130.30	4625.72	2.77	266.15	1.80
	diesel car	164.37	1936.61	2.99	104.60	9.71
	petrol car	5.39	1567.15	3.59	1804.11	198.54
2028	bus	132.24	4694.37	2.81	270.10	1.83
	diesel car	165.01	1944.09	3.00	105.00	9.75
	petrol car	5.41	1573.34	3.60	1811.23	199.33
2029	bus	134.20	4764.02	2.86	274.11	1.86
	diesel car	165.70	1952.28	3.01	105.45	9.79
	petrol car	5.43	1579.97	3.62	1818.86	200.17
2030	bus	136.19	4834.67	2.90	278.17	1.88
	diesel car	166.46	1961.21	3.03	105.93	9.84
	petrol car	5.45	1587.06	3.64	1827.03	201.06
2031	bus	138.21	4906.31	2.94	282.29	1.91
	diesel car	166.20	1958.17	3.02	105.77	9.82
	petrol car	5.45	1584.63	3.63	1824.23	200.76
2032	bus	140.27	4979.44	2.98	286.50	1.94
	diesel car	165.13	1945.48	3.00	105.08	9.76
	petrol car	5.41	1574.15	3.61	1812.16	199.43
2033	bus	142.34	5053.07	3.03	290.74	1.97
	diesel car	163.15	1922.23	2.97	103.82	9.64
	petrol car	5.34	1555.26	3.56	1790.42	197.04
2034	bus	144.46	5128.19	3.07	295.06	2.00
	diesel car	160.50	1890.95	2.92	102.13	9.48
	petrol car	5.26	1529.91	3.50	1761.23	193.82
2035	bus	146.60	5204.31	3.12	299.44	2.03
	diesel car	156.19	1840.25	2.84	99.40	9.23
	petrol car	5.12	1489.17	3.41	1714.33	188.66

presents the results of the calculations for the monitored period and the amount of pollutants in kilograms separately for buses, petrol automobiles, and diesel automobiles.

For the valuation of pollutant costs from transport, it is no longer necessary to divide according to vehicle category.

Table 20. Total amount of pollutants emitted from road vehicles prediction.

Total Amount of Pollutants (kg)
Year	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3
2025	295.03	7969.51	9.22	2153.24	208.49
2026	297.52	8048.53	9.29	2163.61	209.23
2027	300.06	8129.48	9.35	2174.86	210.06
2028	302.65	8211.80	9.42	2186.34	210.90
2029	305.33	8296.27	9.49	2198.41	211.81
2030	308.10	8382.94	9.56	2211.13	212.78
2031	309.85	8449.10	9.59	2212.29	212.49
2032	310.80	8499.06	9.59	2203.74	211.13
2033	310.84	8530.56	9.56	2184.98	208.64
2034	310.21	8549.04	9.50	2158.43	205.30
2035	307.91	8533.72	9.37	2113.17	199.92

therefore presents the aggregate calculations of the individual emitted pollutants for all three categories of road vehicles.

After quantifying the physical units of pollutant emissions, i.e., quantifying the amount, it is possible to proceed to the valuation of these pollutant units in monetary units. For the valuation, as in rail transport, Table 6 is used, and the results are presented in

Table 21. Prediction calculation of the external monetary impacts of environmental pollution from road passenger transport.

Pollutant Costs in Road Transport (EUR)
Year	Pollutant Type
	PM2.5	NOX	SO2	NMVOC	NH3	Total
2025	27,467.12	184,892.73	146.64	2368.56	8026.82	222,901.87
2026	28,323.80	190,750.16	151.36	2596.33	8243.56	230,065.20
2027	29,045.82	195,920.51	155.23	2609.83	8402.27	236,133.66
2028	29,689.99	200,368.00	158.22	2623.60	8562.74	241,402.56
2029	30,380.32	205,747.43	161.29	2638.10	8726.68	247,653.82
2030	31,056.74	210,411.82	165.39	2653.35	8873.08	253,160.39
2031	31,605.07	214,607.18	167.87	2875.97	8967.01	258,223.10
2032	32,105.71	218,425.94	169.80	2864.87	9015.06	262,581.36
2033	32,482.45	222,647.67	171.09	2840.48	9013.46	267,155.15
2034	32,820.28	225,694.77	171.89	2805.95	8992.35	270,485.24
2035	32,946.52	227,850.34	171.48	2747.12	8856.41	272,571.86

.

Table 21 presents the results of the monetary impacts of environmental pollution from road transport and it can be stated that the amount of pollutant costs increases every year despite the increasing share of electromobility.

6. Discussion and Conclusions

Rail transport is considered an ecological mode of transport primarily due to its externalities. For comparison, we selected a line that is considered inefficient due to single-track operation and limited capacity, which affects speed and capacity. The type of line also has a significant impact on the environmental performance of rail transport. This line is not electrified and therefore transport is provided by diesel multiple units. According to the general claim, rail transport should be more environmentally friendly than road transport. To verify this claim, the monetary impacts of environmental pollution from transport were calculated in this article for the selected line, where passengers from rail transport were transferred to road transport according to passenger preferences, assuming that rail transport were discontinued. The Cost–Benefit Analysis method was used in the calculations, which is used in the economic evaluation of transport projects. Verification of the claim that rail transport is more environmentally friendly than road transport on the given line is presented in

Table 22. Comparison of the predicted external monetary impacts of environmental pollution between road and rail transport on the Kralovany–Trstena line.

Pollutant Cost Comparison (EUR)
	Transport Type		Cost Difference (Rail − Road)
	Road	Rail
2025	351,915.84	222,901.87	−129,013.97
2026	365,139.36	230,065.20	−135,074.16
2027	376,795.60	236,133.66	−140,661.94
2028	387,600.37	241,402.56	−146,197.81
2029	398,981.46	247,653.82	−151,327.64
2030	410,117.07	253,160.39	−156,956.68
2031	421,537.88	258,223.10	−163,314.78
2032	432,972.26	262,581.36	−170,390.90
2033	444,694.13	267,155.15	−177,538.98
2034	456,690.08	270,485.24	−186,204.84
2035	469,083.06	272,571.86	−196,511.20

.

From Table 22 it follows that the monetary impacts (costs) of pollutants in road transport are lower than in rail transport.

Table 23. Comparison of monitored pollutants between road and rail transport on the Kralovany–Trstena line.

Predicted Pollutant Costs (EUR)
Year	Pollutant Type
	PM2.5		NOX		SO2		NMVOC		NH3
	Road	Rail	Road	Rail	Road	Rail	Road	Rail	Road	Rail
2025	23,244.87	27,467.12	231,095.27	184,892.73	79.62	146.64	1314.72	2368.56	96,181.36	8026.82
2026	24,116.87	28,323.80	239,782.05	190,750.16	82.63	151.36	1369.96	2596.33	99,787.84	8243.56
2027	24,886.16	29,045.82	247,444.05	195,920.51	85.24	155.23	1414.46	2609.83	102,965.68	8402.27
2028	25,599.78	29,689.99	254,550.67	200,368.00	87.71	158.22	1459.97	2623.60	105,902.24	8562.74
2029	26,352.78	30,380.32	262,023.37	205,747.43	90.28	161.29	1506.52	2638.10	109,008.52	8726.68
2030	27,084.58	31,056.74	269,337.41	210,411.82	92.80	165.39	1554.10	2653.35	112,048.17	8873.08
2031	27,840.21	31,605.07	276,835.20	214,607.18	95.38	167.87	1602.91	2875.97	115,164.18	8967.01
2032	28,589.63	32,105.71	284,353.03	218,425.94	97.96	169.80	1652.64	2864.87	118,279.00	9015.06
2033	29,363.12	32,482.45	292,056.22	222,647.67	100.59	171.09	1703.62	2840.48	121,470.57	9013.46
2034	30,155.46	32,820.28	299,918.97	225,694.77	103.28	171.89	1755.72	2805.95	124,756.65	8992.35
2035	30,969.90	32,946.52	308,058.78	227,850.34	106.09	171.48	1808.94	2747.12	128,139.34	8856.41

compares the individual pollutants in rail and road transport.

Table 23 shows that rail transport has higher monetary impacts compared to road transport for the pollutants PM_2.5, which are fine particulate matter; SO₂—sulphur dioxide; and NMVOC. Conversely, road transport has higher quantified monetary impacts compared to rail transport in the case of nitrogen oxides (NO_x) and significantly lower monetary impacts in the case of ammonia (NH₃). It should be emphasised that, in the case of individual automobile transport, electric vehicles were not considered in the calculations, as these vehicles do not generate these pollutants. The trend of electric vehicle purchases in Slovakia shows an increasing tendency (Table 1).

In the case of rail transport, the use of diesel multiple units on the given line has a significant impact on the monetary impacts of pollutant emissions. If the line were electrified, similarly to electric vehicles, pollutants would not be produced. However, this line is not sufficiently significant to be included in the planned electrification of lines in the Slovak Republic. Another option for reducing pollutant emissions in rail transport would be the purchase of hybrid units (BEMU). However, this would require substantial investment, and the return on investment, given the transport intensity on the Kralovany–Trstena line, would be very long.

In conclusion, it can be stated that pollutants are not the only externality affecting transport costs. Other externalities include accidents, vehicle operation, greenhouse gas emissions, and noise. The monetary assessment of these externalities is part of the authors’ further research.