Relation Between Pre-Warning Time and Actual Train Velocity in Automatic Level Crossing Signalling Systems at Level Crossings
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Article citation info: 39 Łukasik J. Relation between pre-warning time and actual train velocity in automatic level crossing signalling systems at level crossings. Diagnostyka. 2021;22(2):39-46. https://doi.org/10.29354/diag/133700 ISSN 1641-6414 DIAGNOSTYKA, 2021, Vol. 22, No. 2 e-ISSN 2449-5220 DOI: 10.29354/diag/133700 RELATION BETWEEN PRE-WARNING TIME AND ACTUAL TRAIN VELOCITY IN AUTOMATIC LEVEL CROSSING SIGNALLING SYSTEMS AT LEVEL CROSSINGS Jerzy ŁUKASIK Silesian University of Technology, Faculty of Transport and Aviation Engineering [email protected] Abstract At level crossings equipped with automatic level crossing signalling devices (which are category B and C crossings in Poland), warning time depends on several factors including the length of what is referred to as the level crossing’s danger zone for road vehicles, and the train velocity. These systems are designed by taking into consideration the maximum train velocity applicable to the given railway line, which is why a train running with a velocity that is lower than the maximum one, e.g. a freight train, produces pre-warning time excess. The pre-warning time excess affects the redundant prolongation of the time when the level crossing is closed for road vehicles. What has been proposed in the article is to reduce the pre-warning time excess by making the pre-warning time depended on the actual train velocity. It describes a structural concept of a solution which should first be implemented in automatic level crossing signalling systems. Owing to adequate assumptions, the concept of the pre-warning time excess reduction exerts no negative effect on safety at level crossings. Keywords: automatic level crossing signalling systems, pre-warning time, velocity sensor POWIĄZANIE CZASU OSTRZEGANIA WSTĘPNEGO Z RZECZYWISTĄ PRĘDKOŚCIĄ POCIĄGU W SYSTEMACH SSP NA PRZEJAZDACH KOLEJOWO-DROGOWYCH Streszczenie Czas ostrzegania na przejazdach kolejowo-drogowych wyposażonych w samoczynną sygnalizację przejazdową SSP (w Polsce przejazdy kategorii B i C), zależy m.in. od długości tzw. strefy niebezpiecznej przejazdu dla pojazdów drogowych oraz prędkości pociągu. Systemy te projektowane są dla prędkości maksymalnej pociągu obowiązującej na danej linii kolejowej, dlatego pociąg jadący z prędkością mniejszą od maksymalnej np. towarowy generuje nadwyżkę czasu ostrzegania wstępnego. Nadwyżka czasu ostrzegania wstępnego wpływa na nadmiarowe wydłużenie czasu zamknięcia przejazdu dla ruchu pojazdów samochodowych. W artykule zaproponowano skrócenie nadwyżki czasu ostrzegania wstępnego przez uzależnienie czasu ostrzegania wstępnego od rzeczywistej prędkości pociągu. Przedstawiono koncepcję struktury rozwiązania, w które należałoby doposażyć systemy samoczynnych sygnalizacji przejazdowych. Dzięki przyjęciu odpowiednich założeń proponowana koncepcja skrócenia nadwyżki czasu ostrzegania wstępnego nie wpływa na obniżenie poziomu bezpieczeństwa na przejazdach kolejowo-drogowych. Słowa kluczowe: samoczynna sygnalizacja przejazdowa, czas ostrzegania wstępnego, czujnik pomiaru prędkości 1. INTRODUCTION the moment when the train front appears at the level crossing. The pre-warning time excess affects the At level crossings equipped with automatic level redundant prolongation of the time when the level crossing signalling devices, which are category B crossing is closed for road vehicles. and C crossings in Poland, the warning time depends Category B level crossings are those where road on a number of factors, including the length of what traffic is controlled by means of automatic crossing is referred to as the crossing’s danger zone for road systems featuring traffic lights and level crossing vehicles and the train velocity [24]. Such systems gates closing the road traffic in a direction are designed by taking into consideration the train corresponding to: velocity of Vmax applicable to the given railway line, − entry to the crossing, or which is why a train running with a velocity that is − entry to the crossing and exit from the crossing. lower than the maximum one, e.g. a freight train, Category B comprises level crossings of railway produces pre-warning time excess. Pre-warning time lines or sidings and public roads, where: is the time interval between the moment of − the traffic ratio is equal to or higher than automatic activation of traffic lights at the level 150,000, or crossing on account of the train approaching it and 40 DIAGNOSTYKA, Vol. 22, No. 2 (2021) Łukasik J.: Relation between pre-warning time and actual train velocity in automatic level crossing … − the railway line or siding intersects with a and only 31.6% of them are protected by active national road. systems. The problem of safety at level crossings in Category B may also extend over some level Poland has been addressed in papers [20, 29, 30]. It crossings of a lower category which do not meet the should be noted that in Poland, compared to the traffic ratio criterion provided that it is year 2018, the 2019 accident rate increased for substantiated by the local conditions or the category A level crossings, it remained unaltered necessity to improve railway or road traffic safety. for category D, E and F crossings, while it dropped Category B level crossings can be used where a for category B and C crossings. At the same time, public road intersects with no more than three the number of category A and D crossings tracks at a single crossing, and the railway traffic at decreased, while the number of category B and C the given railway line or siding section does not crossings featuring automatic protection systems exceed the maximum velocity of 160 km/h. increased. The author of paper [10] has compared Category C level crossings are those where road the accident statistics of Finland for both passive traffic is controlled by means of automatic crossing and active level crossings by taking direct and systems featuring traffic lights only. fundamental risk factors into consideration. Most Category C comprises level crossings of railway accident took place at passively protected crossings. lines or sidings and public roads where the railway Nearly all direct accident risk factors were traffic at the given railway line or siding section attributable to human error. Research has confirmed does not exceed the maximum velocity of 140 that active warning devices successfully prevent km/h, and: accidents caused by road traffic participants. The − the traffic ratio is equal to or higher than 60,000 authors of paper [3] have ranked Hungarian level and lower than 150,000, or crossings in terms of their safety level with − the traffic ratio is lower than 60,000, and the reference to their prioritisation based on a complex level crossing’s visibility does not meet the scoring system considering accident statistics, technical requirements applicable to category D traffic volume data and various other traffic level crossings [24]. engineering aspects. They analysed and modelled a Level crossings may be equipped with level new method in order to calibrate the model. Their crossing warning signals which inform the train results have made it possible to simplify the scoring driver whether or not the devices installed at the system used for safety assessment. The authors of level crossing to warn road users are in operation. paper [21], on the other hand, have emphasised the The level crossing warning signals are installed in a need for comprehensive monitoring of accidents specific distance from the crossing, being not causes at level crossings and for a computer smaller than the braking distance of a train running program to be designed with the level crossing risk at the velocity of Vmax applicable at the given monitoring in mind. The authors of paper [17] have railway line. In the event that the level crossing attempted to analyse hazardous patterns of warning signal sends no information that the behaviour of drivers at level crossings with warning devices have been activated at the reference to their on-site observations. crossing, the train driver is obliged to reduce its Interpretation of the relevant aspects underpinning velocity to such an extent that the train can be the drivers’ decisions makes it easier to identify the stopped before reaching the crossing whenever an technical solutions which enable the safety level to obstacle posing a threat to traffic safety is identified be increased at level crossings. In paper [19], the at the crossing. Where no such threat is imminent, researchers have discussed the overall body of and yet some incident, e.g. an equipment defect, has problems related the traffic disruptions emerging at occurred, the driver is obliged to continue driving level crossings, and not only those attributable to the train with a velocity not higher than 20 km/h for the inappropriate behaviour of traffic participants, as long as it takes for the train front to pass the but also caused by the proximity of signal- crossing [9]. As regards the need to maintain the controlled intersections. The analysis addressed in required safety level, the solution proposed in this the paper considered T-type intersections. The paper is based on the assumption that level publication also provides a solution which assumes crossings are indeed equipped with level crossing that both systems are linked together, and that the warning signals. signalling control is adequately phased at the nearby intersection. In certain countries, e.g. 2. LITERATURE REVIEW Canada, the standards applicable to level crossing signals [8] determine the distance between a level Level crossings are points of collision between crossing and a road intersection at which the railway traffic and road traffic. The accidents which signalling systems of both should be interfaced. sometimes happen at these locations involve Paper [32] addresses an analysis conducted by an casualties and significant material losses. Paper [1] Expert Group for Safety Improvement at level specifies the number of incidents and accidents crossings in the member states of the United which took place at level crossings in Croatia where Nations Economic Commission for Europe as well 68.4% of all crossings feature passive protection as in several other chosen countries.