Three large scale fire tests were performed with a commuter train inside a tunnel. Two of
the tests used an ignition source inside the train carriage and in one test a pool fire was
placed under the carriage. Both tests wire a fire initiated inside the carriage developed to
flashover conditions. The difference between the two cases was that in one test a standard
X1 carriage was used, while in the second case an X1 carriage was refurbished with more
modern seats and a non-combustible aluminium lining on the walls and in the ceiling. The
time to flashover was significantly different between the two test cases. In the test with
the original seats and linings (test 2) the maximum heat release rate (HRR) was 76.7 MW
and occurred 12.7 min after ignition. The maximum HRR in the case where more modern
seats and aluminium lining were used (test 3), was 77.4 MW and occurred after 117.9
min. For these HRR calculations, the maximum gas temperature near the tunnel ceiling
was used. The corresponding HRR calculated with oxygen consumption calorimetry was
approximately 75 MW in test 3. Based on the temperature measurements in the carriage,
the carriage was flashed over after 12 min in test 2 and after 119 min in test 3.
The main reason for the difference was the difference in initial combustion behaviour
between the case with combustible wall and ceiling lining, and the case with noncombustible
(aluminium) lining as the exposed interior surface. In the case with
combustible lining a ceiling flame was developed, radiating towards the seats and the
luggage spreading the fire more rapidly than in the case without exposed combustible
lining.
The maximum HRR calculated from the experimental results are significantly higher than
those obtained in other documented test series. The luggage in, under or between different
seats was found to increase the fire spread significantly in both cases. This conclusion
was drawn from other tests performed within the same project prior to the full-scale tests
which are reported in full elsewhere.
Borås: SP Sveriges Tekniska Forskningsinstitut , 2012.