# Modernization of Heavy Loaded Tram Radial Effect on Noise and Vibration
## 2 Characteristics of Infrastructure and Modernised Tram Line in Bratislava
### Maternisation of the So-Called Petrzalka Radial--Characteristics of the Tram Line Construction  
The modernisation of the tram line in question is based on the concept of the gradual renewal of the railway infrastructure in Bratislava. It aims to increase the performance of urban public transport and improve the comfort and satisfaction of passengers. A turning point occurred in 2003 when the heavy metro project, which started in the 1980s, was rejected. The alternative is a system of \"fast trans\"--tram rapid transit--running across the Danube from the historic core of the city to the end of the largest residential area in Bratislava--Petrzalka--along the route of the originally envisaged metro and connecting it to the existing tram network. The requirement for modernisation resulted mainly from the technically obsolete and thus unsatisfactory condition of the tram line and the signalling elements on the line and the negative impact of the line on the environment (especially  
Figure 1: Currently operated tram vehicles in Bratislava [26; 27; 28]. in the area of noise and vibration). In connection with the considered combination of the tram line with the TEN-T train transport (construction of a dual gauge line--1000 mm and 1435 mm), the first part of the modernisation of the so-called Petrzalka radial was proposed in 2013. The first part of the construction works included the modernisation of the Old Bridge (replacement with a new bridge structure) and the construction of a double-track line in the length of 2.4 km (from the crossing of Stur and Jesensky Street to the crossing of Jantar Street and Rusovce Road). The second part of the modernisation considers the extension of the tram line to the Petrzalka District. Figure 2 demonstrates the modernisation of the tram line section in question [29]. The Old Bridge dates back to the 19 th century. After several repairs, it was operated until 2013, when it was closed due to an emergency. As the bridge did not meet the minimum navigable corridor on the Danube River, the original steel structure was replaced by a new one. The new steel construction features a higher bearing on the pillars and a larger span of the main middle field. The tram line is located in the middle of the bridge in a reinforced concrete carriageway and is used exclusively for tram transport and rescue services. The request for the modernisation of the tram line in question is based primarily on its technically outdated and currently unsatisfactory condition. Structurally, the track consists of 49E1-shaped rails placed on concrete sleepers in an open track bed. In the section of the line from the Karlova Ves turnaround to the Dolne Krace step and in the area of the crossings with a cast surface finish, the track superstructure consists of TV rails. NT1 placed on concrete panels on a gravel bed or sleepers in an open rail bed. The section of the line from the intersection of Liscie udolie-Botanicka streets to the Molecova stop is the TV rails. NT1 stored on VUIS panels have already been extensively destroyed. In particular, the track sections set up on the panel structures due to their technical condition were a source of high levels of noise and vibration, creating a significant noise load in the areas through which the tram line is led. The effort to modernise the Dubravsko-Karloveska radial section follows on from the concept of gradual renewal of the railway infrastructure of the Capital City of the Slovak Republic, Bratislava. The main purpose of the construction was to modernise the technical infrastructure of the line to achieve the following requirements:  
* increase in line speed;
* increase in spatial permeability;
* increase in the bearing capacity of the track bottom;
* increase in operational safety;
* increasing passenger safety;  
Figure 2: Modernisation of Petrzalka radial [30; 31]. * increase the culture, comfort, and fluidity of travel;
* reduction of negative impacts of rail traffic on the population;
* improving and upgrading the environment.