Maximum safety in public local passenger transport

In order to obtain a reliable database for the bogies of its new tramways the Innsbrucker Verkehrsbetriebe und Stubaitalbahn GmbH has purchased a ROMER Absolute Arm. This mobile measuring arm not only provides the company with data for its guarantee claims, it also appeals because of its high measuring accuracy and because it is straightforward to use.

With almost 50 million passengers per year, Innsbrucker Verkehrsbetriebe und Stubaitalbahn GmbH (IVB) is one of the largest public local passenger transport operators in Austria. A workforce of 600 ensures that the transport of passengers along the 30 lines of the approx. 341 km long network proceeds reliably and safely. Because the 160 modern Mercedes Citaro busses and the 32 new tramways of the type Bombardier Flexity Outlook Cityrunner cover about 8.5 million kilometers in and around Innsbruck per year.

All accident repairs, servicing, maintenance and also the statutory inspections of all vehicles are carried out in an impressive workshop complex that offers a view of the Nordkette mountain range. So that staff are also available in emergencies, the workshop with its 100 employees is staffed from Monday to Sunday almost twenty-four hours a day.In the tramway team area a bogie with a measuring arm placed in its centre catches the eye immediately. “With the ROMER Absolute Arm, which we purchased just over a year ago, we aim to make changes to the bogie detectable”, explains Helmut Egger, deputy workshop manager at IVB. “Because of the way the bogie is built and how it can be measured, the measuring arm is not only the best option for us but probably the only alternative for measuring it.”

Comprehensive initial measurement

The event that triggered the investment in the measuring system was a heavy accident with one of the new tramways which were put into service between 2008 and 2011. Following the accident, the company was not able to determine with 100% certainty whether the bogie sustained any damage. Even when the unit that carries the tramway body and contains the drive unit - the motor and gearbox - was sent to Bombardier for investigation it was not possible to answer the question conclusively. Following the purchase of the measuring arm, the IVB is now in a position to properly assess whether there was any deformation to the bogie. In order to obtain the necessary data an initial measurement of all 99 bogies was carried out. Each tramway has three bogies and in addition there are three reserve units. The measurement is carried out when the wheel rim is changed, which is due after two to three years of service. “While the actual measuring of the bogie takes three hours including setting up and recording, we need several days beforehand for the preparation of the unit. Because the bogie has to be cleaned and the wheel rims changed”, reports Helmut Egger. “After measuring the bogie we quickly fit it back into a vehicle because we only have a few reserve units. We therefore have to work with maximum efficiency.

Reliable database

Currently, the IVB is still involved with the initial measurements. Not only are these very labour intensive, they also involve a lengthy process. However, it is worth the effort because the measurements of the bogies - which are scheduled to be carried out every two to three years when the wheel rims are changed - provide the Innsbruck company with a reliable database. This is needed for a number of reasons, not least for the technical inspection which is legally required for tramways every eight years. With the recorded data it is possible to answer various questions: how does the bogie develop? Where are deformations? What is the effect of the service during this period? After all, each tramway covers about 50,000 km annually. But the data obtained with the help of the ROMER Absolute Arm also play an important role for IVB in terms of its longerterm guarantee claims. Because it provides them with the evidence of changes. In that way the ROMER measuring arm helps to ensure safety for the Innsbruck tramways. Another important aspect is that of safety after accidents: with the help of the measuring arm and the comparative measurements it is possible to establish whether the bogie has suffered any damage or deformations. Following accidents, the survey document is also submitted to the accident assessors.

Unique features

The unit used by the Innsbruck company is the ROMER Absolute Arm 7345 with 4.5 m measurement volume – a size only offered by Hexagon Metrology. The IVB needs this measurement volume because of the 2.5 m diameter of the bogie. The ‘long arm’ is needed in order to reach all parts of the bogie. When the measurement system was presented to IVB its straigthforward handling did not fail to impress the company. In spite of its size, the arm weighs less than 9 kg and is therefore both mobile and easy to relocate. Even the ‘large’ ROMER measuring arms are perfectly balanced and easy to operate because of the ‘Zero G’ weight balancing device and the infinite rotation in all axes. Another important feature of the mobile measuring system that is important for IVB’s day-to-day work is the absolute rotary pulse generator. Because this means that the ROMER Absolute Arm does not have to be referenced but is immediately ready for service after it is switched on. “Likewise, the system’s automatic probe detection is of clear benefit to us. Because we don’t have to worry about anything“, stresses Helmut Egger. “We just fit the respective probe and the measuring arm automatically detects the probe head. For us that is a very customer-friendly standard.“

Other transport companies are interested

But that is not the only reason why the ROMER Absolute Arm 7345 quickly became popular at IVB. Its measuring accuracy in the 1/100 range is much appreciated as the unit is also used for comparative measuring. The measuring process is so straightforward that it can be handled by operators who are not qualified measuring technicians: about 100 measuring points per bogie have been specified in the measuring software - including a photograph and any additional information that may have to be observed. This means that the operator carrying out the measurements can proceed point by point. As a result of their measurements, IVB has already found out that there are deviations of between four and five millimeters between the bogies as these are individually manufactured by hand. The company is very satisfied with the ROMER Absolute Arm because it fully covers their application with the bogie. “We are very pleased with the measuring system because of its accuracy, straightforward operation and easy handling. What is more, the service provided by Hexagon Metrology is very good“, - that is Helmut Egger’s positive conclusion. “My colleagues from the other large Austrian transport companies are also very interested in our experience with the mobile measuring arm.”