Metro Tunnel Fire Tests in Sweden

Large-scale fire tests of commuter rail wagons were carried out in Sweden as a part of the ‘Metro’ project. These tests were carried out with full-scale wagons in a tunnel. The objective is to obtain better information about the differences in fire behavior between older- and newer-type wagons. Explosion tests were also carried out as a part of the test program.

The Metro project involved the staging of unique, full-scale fire tests carried out in commuter train carriages in a Swedish tunnel in September 2011. Mälardalen University in Västerås is leading the project in co-operation with eight other organizations. These are: SP Technical Research Institute of Sweden, Lund University, the Greater Stockholm Fire Service, SL (Greater Stockholm Area Transportation Company), FOI Swedish Defence Research Agency, CRISMART (Swedish National Defence College), the Swedish Fortifications Agency and the University of Gävle.

SP Fire Technology is responsible for the large scale tests, where the aim is to determine an appropriate design fire for metro/commuter trains. The commuter trains used, which comprised one motor wagon and two passenger wagons, were equipped with measuring instruments. Additionally, the internal lining of one of the wagons was changed from combustible to non-combustible. The aim was to see if there was any difference in the fire behavior of the wagon types. Another parameter applied was the amount of luggage used in the tests. The amount, approximately 5.4 kg/sq m, was the same as was found in a survey carried out on the Stockholm metro.

The work on design fires involves investigating which parameters will affect the spread and progress of a fire, and the nature of the conditions both inside and outside a burning carriage. The work includes comparing test results at various reduced scales with those of full scale tests carried out in a railway tunnel, which is the culmination of the work.

With access to three commuter train carriages, the main purpose of the tests is to investigate how a fire develops, and what are the consequences of an explosion in a carriage. The full scale tests were performed in the Brunsberg tunnel, an abandoned 276-m tunnel.

Due to the few tests that were possible, there was limited potential to vary the different parameters and conditions. However, what became clear was the importance of the choice of lining materials inside the carriage on the fire behavior. Further, the importance of luggage and its contribution to the overall fire load was clearly demonstrated as its involvement in a fire can lead to a very rapid fire spread. On the other hand, high-performance lining materials can considerably delay the onset of flashover.

A phenomenon seen in tests carried out by SP in 2003 in the Runehamar tunnel was observed once again. The bulk of air in the tunnel started to pulsate, resulting in flames and smoke traveling backward and forward at a very precise frequency. The control of back-layering was shown to be very important. When the mobile ventilator used could no longer maintain the set speed due to the size of the fire, a rapid development of backlayering occurred. This surprised the fire fighters inside the tunnel. The heat release rate was most likely higher than obtained in other similar tests, but the final results of the analysis will be given at the ISTSS conference in New York, March 14-16, 2012. More information about ISTSS can be found at: www.istss.se.
The Metro project (www.Metroproject.se) is a three-year undertaking, running until the end of 2012, with Mälardalen University (www.mdh.se) in charge.

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Baku, Azerbaijan’s Third Metro Line Get Under Way

On Aug. 22, 2011, construction of Baku, Azerbaijan’s third metro line got a jump start with the launch of a Robbins EPB. The 6.3 m (20.7 ft) diameter TBM for contractor Azerkorpu is one of two EPB machines excavating parallel 3.5 km (2.2 mi) tunnels approximately 15 m (50 ft) apart.
The capital city Baku is home to 1.7 million people and is known for its chronically clogged city streets. Improved transportation infrastructure is a country-wide initiative in Azerbaijan, where the economy is rapidly growing due to substantial oil reserves. “Azerbaijan is poised to become one of the richest countries in the world. There is no doubt that with the increase in economic interest the population will soon outgrow the already outdated and undersized transportation infrastructure,” said Evan Brinkerhoff, Robbins Field Service Superintendent.

So far, the ground has consisted of full-face clay, similar to London blue clay, with no appreciable ground water, pebbles or soil. “The material is sticky, and our initial advance was limited because the pit size was only long enough to muck out with one car. Our machine performance has since improved,” said Brinkerhoff.

As the TBM mines, it is placing 5+1 universal concrete segments using Robbins-supplied segment plant. Muck is being stored in separate storage stations for each TBM, and is then trucked away during the day.

The Robbins machine features a mixed ground cutterhead with carbide bits that are interchangeable with disc cutters depending on the geology. Four independent foam injection points in the cutterhead evenly consolidate the face in the ground conditions. The design results in decreased cutterhead wear and a smooth flow of muck into the mixing chamber.
The new metro Line 3, for owner Metrostroy Azerbaijan, will connect to the existing Line 1 as well as a new bus station. The EPBs are excavating two sections connecting Cavadxan Station and Avtovagzal station sites. Upon completion of the first leg, the machines will continue on to excavate between the Memar Ajami-2 station and an as-yet-unnamed station located near the Azerbaijani Defense Ministry’s hospital. The stations are expected to open in 2013.