Train accident on Denmark bridge because of wind load

Six people have been killed and 16 others injured in a train accident on a bridge connecting two islands in Denmark, rail operator DSB has said. “We can confirm that six people are dead,” a duty officer told AFP, as media reports said the roof of a cargo train blew off in heavy winds and hit a passenger train that was travelling in the opposite direction. The accident occurred at around 6.30am Irish time on the Great Belt Bridge connecting the islands of Zealand, where Copenhagen is located, and Funen. A Funen police spokesman told reporters he could not provide details of the accident,but added: “We know that an object hit the train.” Passenger Heidi Langberg Zumbusch had just boarded the train and taken her seat when the accident happened. “There was a loud crash and the windows started smashing onto our heads. We flew down onto the floor, and then the train stopped,” she told Danish public broadcaster DR. Bo Haaning, of the Danish Accident Investigation Board, confirmed to CNN that the trailer had fallen off the freight train and hit the passenger train, but said it was not yet known whether this caused the accident or happened during it.

Great Belt Bridge
Great Belt Bridge 

The strong winds can blow the train off tracks and cause overturning derailment accidents. For instance, the requirement of increasing train speed will inevitably result in higher aerodynamic loads on the vehicle. The effects of crosswind on the ground vehicle have received increasing concerns in terms of traffic safety. To ensure the vehicle safety, it is necessary to assess the risk of vehicle accidents due to strong crosswind, which is a complex and multidisciplinary task involving the stochastic characteristic of wind process, aerodynamic actions of crosswind and the dynamic model of vehicle. Baker (1987),established the analytic model of vehicle under crosswind and investigated the critical wind speed for vehicle safety based on wind tunnel tests. To reduce the problem solid barrier can be installed on the bridge. When a solid wind barrier is installed on bridges, the relative movement between vehicles, bridges and solid wind barriers has some influence on the aerodynamic characteristic of vehicles. In general, smaller values of lift force coefficients were obtained from experiments with the moving model than the static one at small yaw angles (HuoyueXiang).

 

Train Fail_1
Cargo train

The other problem is wind-borne debris do to wind load, Wind-borne debris created by strong wind events, particularly hurricanes, is a major source of damage to the built environment. Although the problem is most significant during the strongest winds associated with tropical storms and tornadoes, wind borne debris also occurs in extra-tropical cyclonic storms such as those that occur in Northern Europe.

Debris
Debris

 

Debris picked up by the wind can rapidly accelerate to reach and even exceed the background wind speed. The debris can travel significant distances (ranges of over one hundred meter have been reported) and can have significant momentum when it impacts the ground or downwind buildings. Clearly, in an urban environment, the risk of damaging impact with other structures is much higher and there are also risks associated with cars and pedestrians in the streets. Several fatalities have been reported in the media with people or vehicles struck by debris. To know the trajectory of debris, numerical model and wind tunnel testing should be perform. The equations of motion for debris flight are derived in a generalised dimensionless form that reveals the fundamental controlling parameters of the problem (Baker). Simplified forms of the equations are then derived for compact and sheet debris, and the large time asymptotic solutions derived for velocities and energies. Numerical solutions of the equations of motion are presented for a range of the controlling dimensionless parameters that are typical of full-scale conditions. The results are compared as far as possible with experimental data. The results for compact debris are well defined and the predicted dimensionless velocities and trajectories are a function of a single dimensionless parameter (Baker 2006).

 

 

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