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The news pages of this website have recently reported on the trackwork renewal currently taking place at North Pier which will see a section of the southbound and centre tracks renewed, along with the removal of one of the two crossovers. To facilitate the work at this location single line working of the tramway between North Pier and Gynn Square is currently in force. This allows the Council's Operational Services Department to work unhindered on the tracks under possession, allowing the work to be completed more quickly. This feature
by James Millington explains exactly what is meant by the term 'single line working', and what is necessary to allow its safe set up and operation. Single line working can be clearly defined as the method of working which is required to take place over one track of a double track tramway when one of those lines is out of use due to rail replacement, or because of an obstruction. It is a temporary arrangement which can either be set up at short notice if a line suddenly becomes blocked by an operating incident, or can be pre-planned by a meeting of various departments to facilitate major rail replacement work. This is the situation which is currently in place between North Pier and Gynn Square. The length of the single line section depends on the availability of crossovers, the location at which pointwork exists whereby trams can cross from one line to the other. This can often be quite a distance, which affects the reliability of the timetable as trams can be kept waiting at either end of the section for the single line to clear. Whilst reliability is an issue, the safe operation of the single line section is of paramount importance, to avoid any possibility of conflicting movements. To ensure safe operation a number of safety features are in place, starting with a locked barrier blocking the entrance to the section which is to be temporarily closed. This is supplemented by an additional barrier protecting (at one end of the single line section) the entrance to the line which is to remain open, and (at the other end) the crossover required to access the line in use. Designated track supervisors are the only people authorised to allow trams onto the single track section, and the final tram of each convoy through carries a baton which must be handed to the supervisor in charge at the other end before any cars are allowed through in the opposite direction. This age old system of signalling is still seen as the safest method available to ensure trams do not meet each other head-on on the single line section. It requires the tram drivers to be briefed that they must not proceed onto the single line unless they have either seen the baton (if they are not the only tram passing through the single line section), or to be in possession of it if the last car through the section. As a final safety measure, radio contact between the two ends of the single line is also maintained at all times. To avoid accidents between pedestrians or motorists who could come into conflict with a tram making a wrong direction movement, additional signs or barriers are employed to avoid this with an example currently being around the Metropole street track where the line remaining in use has been completely coned off to prevent a southbound tram meeting northbound motorists. So, using the current example of North Pier to Gynn Square we will take a journey through the single line section, initially heading north. As it is the northbound line which has remained open our tram will not actually deviate from its usual route in this direction. However, prior to the points for the loop line at North Pier we come to the barrier protecting the line in use. A portacabin has been placed here to provide an office for the track supervisors, and the northbound tram stop has been temporarily relocated from the shelter to this location, allowing cars awaiting the single line to load passengers here and thus save time. Once the single line has become clear, the barrier is swung open to allow us through. We take the baton (or observe it in the possession of the track supervisor if it is to be handed to a following car), and proceed as normal to Gynn Square. At this point is another track supervisor, to whom we pass the baton once we have cleared the single line section before continuing the journey north as normal. When travelling south, a barrier is situated at the bottom of Gynn Hill, on the southbound line before the crossover. We wait here until the northbound tram from North Pier has passed by and handed the baton to the track supervisor. They will then hand the baton to us (or show it to us if another car is to follow). We pass through the opening barrier and into the headshunt created between the crossover and the locked barrier protecting the closed section of the southbound line. Once we have cleared the crossover, the driver changes ends and drives the tram over the points onto the northbound line. Here they change ends again, before proceeding south on the northbound track. Care now has to be taken as pedestrians, and waiting passengers at the intermediate stops to North Pier may not be expecting the tram to approach on the wrong line. On reaching North Pier, the tram continues up to the opening barrier outside the track supervisors portacabin. Here, another end change is required, as the tram is driven back onto the centre track to clear the crossover. The driver changes ends again and the tram crosses to the southbound line to continue its journey, handing the baton to the track supervisor once the single line is clear. |
