Reliable fire-safety for the
Cassanawald Tunnel

The Cassanawald Tunnel forms part of the northern approach ramp of the A13 motorway close to the San Bernardino Tunnel, and serves as an avalanche shield for the road. It features two-lane contraflow traffic for its length of 870 m, and is located in the Canton of Grisons.

The following modifications were implemented in mid-2010 in order to provide reliable protection against fire damage for this tunnel:

Demolition of the salt-decayed wall structure to a residual height of 2.60 m, and its restoration with new polypropylene-fibre-reinforced structural concrete. This fibre-reinforcement system is known to reduce or even eliminate spalling of the concrete in case of fire.

Installation of a special fire-safety mortar (the BASF „Meyco Fireshield 130“ system) on the tunnel roof; a high-pressure water jet (2000 bar) was first used to roughen and clean the original concrete, in order to ensure total adhesion of the fireproof mortar to the substrate, the adhesion requirement for this refractory safety mortar being not less than 1MPa; the necessary substrate roughness was determined by means of on-the-spot inspection and continuously verified using a laser profilometer.

The safety mortar was then sprayed on to the tunnel roof (layer thickness: approx. 40 mm) by a spraying robot using the wet-spraying method at a daily application rate of up to 30 m³. The tunnel was closed in one direction to permit performance of this work, and rails laid in the traffic-free lane to carry flatcars, which were used as mobile platforms for installation of the fireproof spray mortar (total application: 12,000 m²).

The fire-safety system installed here, supplied by BASF Construction Chemicals Europe AG, of Zurich, fulfils the strict requirements of the RWS fire-load curve (e.g. assured fire resistance after 10 minutes at 1200 °C and even after one hour at 1350 °C). The work was performed by Bauunternehmung Marti AG, of Lucerne. ⇥G.B.


Related articles:

Issue 06/2011 6th International Congress in Hamburg?/?D

Traffic and Safety in Road Tunnels

Is there a link between underground transportation facilities and the events in April 2010 when relatively unexpected a volcano on Iceland erupted and grounded air traffic throughout Europe and in...

Issue 04/2014 Belgium

Kennedy Rail Tunnel – new Fire Protection Measures

The Kennedy rail tunnel running beneath the Schelde to the south of Antwerp was built in 1969 for the Antwerp-Gent link. Owing to enhanced safety measures, which have since been introduced, the tunnel...

Issue 01/2015 Switzerland

Increased Safety for the Belchen Tunnel

The Swiss Federal Roads Office (FEDRO/ASTRA) intends increasing safety in the 3.2 km long Belchen Tunnel on the A2 motorway. Towards this end it has invested 128 million Swiss francs since 2008. The...

Issue 02/2013 Austria

Pfänder Tunnel: 2nd Bore opened for Traffic

The 6,585 m long, two-lane Pfänder Tunnel on the A14 in Vorarlberg/Austria with an average daily frequency exceeding 30,000 vehicles is being provided with a second bore, which is also 2-lane, to...

Issue 07/2010 Switzerland

Silvaplana Tunnel – High Demands on Safety

For generations Silvaplana has represented an important traffic hub between North Bünden and the Engadin. Transit traffic is increasingly being seen as a burden. At the end of 2007 an outline project...