Evaluation of Passenger Car Emission Indexes in Relation

to Passing through the Rail-road Crossing

Mateusz Nowak

, Maciej Andrzejewski

, Sylwin Tomaszewski

, Paweł Daszkiewicz

and Patryk Urbański

Lukasiewicz Research Network, Rail Vehicles Institute "TABOR", Warszawska 181, Poznan, Poland

Keywords: Exhaust Emission, Rail-road Crossing, RDE, PEMS, on-Road Measurement, Route Selection, Smooth Traffic

Flow, Sustainable Transport System, Road Congestion.

Abstract: One of the crucial aspects in the vehicles exhaust emission is, often the long duration of vehicles stop phase

before the rail-road crossing before the rail vehicle passes through. During the road vehicle stop, the

combustion engine in most cases operates in idling conditions. Some drivers turns off the combustion engines

during mentioned stop time. In modern vehicles there is also the start&stop system implemented, which

automatically stops and starts the combustion engine. Combustion engine idling phase is related to inefficient

operation, where after switching the engine off, the catalytic converter could cool down, which could result

in increased emission of harmful exhaust compounds after start of the engine. The analysis made in reference

to the Poznan agglomeration, shows many places where alternative routes can be determined with regard to

the necessity of reaching the destination, when there is a road-rail crossing on the way. The purpose of the

performed work was first of all to determine the potential of reducing fuel consumption and exhaust emission

by cars as a result of the improvement in the transport system efficiency. The improvement of transport system

efficiency could be assumed as a trip duration reduction, when the driver could receive the information about

the actual state of the rail-road infrastructure.

1 INTRODUCTION

The rail-road level crossings are very important part

of transport infrastructure. There are well known non-

collision rail-road level crossings, which are the best

in case of safety and this solution is the most

comfortable, because it does not interrupt the road

vehicles trip. The non-collision level crossings are

much more expensive and need more place, which is

crucial in urban locations, that is why most of the

existing level crossings consists of railway and road

routes placed on the same level. Based on the data

from European Railway Agency and The

International Union of Railways, there are about

114,000 level crossings in the European Union and

600,000 level crossings in the world. In that case, it is

important to ensure enough safety to prevent the

accidents. According to a report Railway Safety

https://orcid.org/0000-0003-1966-0423

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https://orcid.org/0000-0003-0143-2166

Performance in the European Union 2016, there were

2076 significant accidents in 2014, reported by the

EU-28 countries. The traditional level-crossings are a

big challenge to ensure enough safety both for train

and road vehicle users, and that cases are a subject of

scientific papers (Kobaszynska-Twardowska et al,

2018). According to polish law, there are six different

categories of rail-road level crossings, described by a

letters from A to F. The features of different

categories were actualized in the year 2015, assuming

among others the new technical specification of trains

or infrastructure control systems (Młyńczak, Folega,

2016). Assuming the basic two types of level

crossings, much higher level of safety ensure the ones

equipped with warning or protection devices, called

as active, than the ones described as passive – not

equipped with warning or protection devices

(Laapotti, 2016). There are many works on improving

Nowak, M., Andrzejewski, M., Tomaszewski, S., Daszkiewicz, P. and Urba

nski, P.

Evaluation of Passenger Car Emission Indexes in Relation to Passing through the Rail-road Crossing.

DOI: 10.5220/0010465305790583

In Proceedings of the 7th International Conference on Vehicle Technology and Intelligent Transport Systems (VEHITS 2021), pages 579-583

ISBN: 978-989-758-513-5

579

the safety on the rail-road level crossings, which

suggest for example use both the Global Navigation

Satelite System and optical sensors for train

positioning in the railway network (Pelz, 2007). This

assumption is favourable, because assumes the use of

cheap and reliable technology. There is also another

way to improve the safety in case of proper routing of

road vehicles.

When the rail-road level crossing is closed, it

increases the road congestion, which actually is a big

problem, especially in big cities, what was reported

by Deloitte and Targeo.pl in a report on traffic jams.

In the road congestion conditions, the vehicles fuel

consumption increases and also very often the

exhaust emission occur very close to the pedestrians.

Properly developed rail-road level crossings and

surrounding infrastructure improves the efficiency of

transport system, which is in accordance with the

main objective of sustainable transport system

(Ogryzek, Adamska-Kmieć and Klimach, 2020). The

Poznan agglomeration develops the public transport

system in case of higher frequency of rail journeys,

which is another step towards the sustainable

transport system and the sustainable development of

the city (De Gruyter, Currie and Geoff Rose, 2017).

The authors made before similar, but simulation

research only in case of trip duration (Laapotti, 2016).

The results were positive in case of longer stop times

on rail-road level crossings, which occur very often in

polish conditions.

The aim of the authors was to check if makes

sense if the driver change the route to avoid standing

in road congestion. The considerations were carried

out on example of rail-road level crossing, located in

Poznan. This location has been selected, because

there is an alternative route with collision free rail-

road level crossing in the close surroundings. The

ecological and economic analysis was carried out and

also the travel time was compared in case of the two

selected routes. The basis for this consideration were

on-road tests of passenger vehicle, performed with

PEMS (Portable Emission Measurement System)

device. That kind of measurements is very

favourable, because it reflects the actual level of

exhaust emission on selected road. Such analysis

could be performed also for whole city or region,

where the number of rail-road level crossings is much

greater and there are more alternative routes, but in

that case a macro scale model is needed. When whole

city will be assumed, there should be an analysis

made, which road transport related emission

modelling method should be chosen – the

consumption-based model, EURO standard based

model or the speed dependent model (Zefreh, Torok,

2016)

2 METHODOLOGY

For the purpose of the article, the authors considered

the rail-road level crossing located on

sw. Michala str. in western part of Poznan. The

analysed route started from the intersection of

Warszawska and sw. Michala streets and finished on

a car park at the end of sw. Michala str. (Figure 1).

The selected route is characterized by high traffic

density and there is possibility of alternative route

selection without rail-road level crossing. The

distance of alternative route is about 2.1 km and it is

approximately 60% more than the primary route.

Figure 1: Analysed test routes (the primary route is marked

with blue colour and the alternative route – grey); prepared

with use of www.google.com/maps (16.10.2018).

The tests were performed in real driving conditions

and the research object was a passenger vehicle

propelled with a turbocharged spark ignition engine,

compliant with Euro 6 emission standard (Figure 2).

Four different scenarios were analysed:

▪ passage through the rail-road level crossing

without stop (described as sw. Michala I),

▪ trip through the rail-road level crossing

including about 1,5 minute stop phase with

started combustion engine (described as sw.

Michala II),

▪ passage through the rail-road level crossing

including about 1,5 minute stop phase with

VEHITS 2021 - 7th International Conference on Vehicle Technology and Intelligent Transport Systems

580

stopped combustion engine (described as sw.

Michala III),

▪ trip through the roundabout Srodka and

Zawady str. (described as Roundabout Srodka-

Zawady).

The assumed stop time seems to be short in polish

conditions, but this was obtained in performed on-

road tests.

Figure 2: Test vehicle with measurement equipment.

The exhaust emission measurements were

performed with PEMS (Portable Emission

Measurement System) device: Semtech-DS,

manufactured by Sensors (Figure 3). This device is

equipped with gas analysers for specified gas

concentrations measurements and collects also

signals from exhaust flow meter, GPS, ambient

module and the vehicles OBD system. That kind of

equipment is nowadays used in additional emission

on-road tests in the vehicles homologation procedure.

Under special conditions stated in the legislative

documents, that test is called RDE. The vehicle’s

engine during all of the analysed tests was already

warmed-up

Figure 3: Exhaust emission measurement device Semtech-

DS with auxiliary components.

3 RESEARCH RESULTS

The results of performed tests are shown on Figures

4-9. The vehicle speed profiles vary because of local

differences in traffic density and the stops on

analysed rail-road level crossing (Figure 4). The

distance values of analysed test routes is about 1.3 km

in the case of primary route and about 2.1 km (+60%)

for alternative route with collision-free rail-road level

crossing (Figure 5). The duration of performed drives

vary between 132 and 253 seconds and thus the

average vehicle speed ranges from 18.4 to 42.6 km/h

(Figure 5). The shortest trip duration was recorded

during passage of the shorter route with opened rail-

road level crossing. Test with use of the longer route

result in about 35% greater drive time. The greatest

duration time values were recorded when the vehicle

was driven through shorter route with closed rail-road

level crossing (204 and 253 s). This values show, that

selection of the longer route with collision-free rail-

road level crossing even by short stop time will result

in shorter trip duration.

Figure 4: The speed profiles during performed tests.

Figure 5: Duration, distance and average speed for different

test drives.

Evaluation of Passenger Car Emission Indexes in Relation to Passing through the Rail-road Crossing

581

As it was revealed, the longer trip distance in

analyzed case could result in shorter trip duration.

The environmental performance of these passages in

terms of gaseous exhaust compounds was also

verified (Figures 6-9). The CO

emission, which is an

effect of fuel consumption, takes the smallest value of

approx. 235 g after passing the primary route with

opened rail-road level crossing (Figure 6). The

greatest CO

emission (382.5 g) was recorded after

the alternative route passage, which was about 21–

24% more than after passing the shorter route with

about 1.5 minute stop. Similar dependencies are

observed in case of CO emission, but comparing to

the shorter route passage, the increase in CO emission

after passing the longer distance is 200% (Figure 7).

The smallest mass of NO

was emitted during passing

the shorter route with closed rail-road level crossing

and the greatest mass of this exhaust compound was

emitted during after passing the alternative route

(Figure 8). Observed dependencies could arise from

different engine operation parameters and thus

different in-cylinder temperatures which have

influence on NO

emission. The greatest HC mass

was measured after test performed with use of the

alternative route (Figure 8).

Obtained emission values were related to the

Euro 6 emission standard. All of performed tests in

case of CO, NO

and HC represent much lower

emission level than the homologation values. Great

influence on such results is that performed tests do not

include the cold start of the engine (when the engine

coolant temperature is on the level of ambient

temperature). The cold start emission will have a

great impact to the results, because of the short

distance of performed drives compared to the

homologation test cycle.

Figure 6: Summarized CO

emission obtained during on-

road measurements.

Figure 7: Summarized CO emission obtained during on-

road measurements.

Figure 8: Summarized NO

emission obtained during on-

road measurements.

Figure 9: Summarized HC emission obtained during on-

road measurements.

VEHITS 2021 - 7th International Conference on Vehicle Technology and Intelligent Transport Systems

582

Figure 10: Comparison of emission indexes reflecting the

measured emission values related to Euro 6 emission

standard.

4 CONCLUSIONS

Performed measurements show the importance of

choosing the route both from the point of view of

travel time and exhaust emissions. In analysed case,

60% longer distance result in 13–30% shorter travel

time, than during drive through shorter route with 1,5

minute stop on closed rail-road level crossing. If only

trip duration will be considered, in analysed case, the

selection of longer route will benefit in shorter drive

time if the stop time will last approx. 1 minute.

The issues related to exhaust emission are more

complicated. The emission intensity depend not only

from travel time and distance, but also from engine

speed and engine load. These very complex rules

affect in the greatest mass of emitted exhaust

compounds after covering the route characterized by

longer distance and higher vehicle speed. Different

engine operating conditions – higher load affect in

greatest increase (over 2 times) in case of NO

emission. Probably greater differences could be

observed in case of vehicles propelled with

compression ignition engines without SCR (Selective

Catalytic Reduction) system, which is responsible for

reduction. The disadvantage of using longer

route in fuel consumption and CO

emission is about

62%. It could be observed, that stop on the rail-road

level crossing contributes to systematic increase of

emission and probably three times longer stop

time on closed rail-road level crossing when the

engine is switched on, will contribute to such increase

of fuel consumption, which will make sense to use the

longer route. The performed test drives represent

much lower emission values in case of CO, NO

and

HC the Euro 6 homologation values. There is no clear

winner in case of the emission indexes. In case of CO,

the lowest emission index was obtained during short

trip through the opened rail-road level crossing. The

most favourable emission index for NOx were

obtained during the short trip, when the vehicle was

parked on the level crossing with started combustion

engine. The HC emission index with the lowest value

was obtained during the passage through the rail-road

level crossing with stopped combustion engine.

That assumption will have sense, when the car

driver will know, that the oncoming rail-road crossing

will be closed and should change the route. It should

be noted that mostly the stop times are significantly

longer than in analysed situation. Deeper insight in

that case will give also the research on the influence

of using different routes in that areas on ecological

and economical indexes from vehicles propelled with

compression ignition engines, which are not equipped

with three way catalytic converters as test vehicle.

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