GSP on the Dorcol tram: human factor and switch check as first leads

Belgrade’s City Transport Company (GSP) said on May 25, several hours after the tram derailment in Dorcol, that there are indications that one of the possible causes might be the human factor, that is, unsafe speed of the vehicle when passing through the switch. The company qualifies that the final cause will be determined only after a technical expert analysis is conducted.

The GSP statement says the analysis will cover several elements, including the technical state of the vehicle itself, the position and serviceability of the switch at the corner of Cara Dusana and Knicaninova, and the working characteristics of the tram driver. The company expressed regret over the injuries to passengers and the driver and wishes them a speedy recovery.

Ivan Bankovic, president of the GSP “Centar” union, told the media that his initial impression is the derailment was caused by a problem with the switch on that stretch. Bankovic warned that part of the route through the city centre has not been refurbished for years, and that switches at such locations require special maintenance. The official assessment, he added, will come from the technical analysis.

Unofficially, tram speed on that part of the route must not exceed 15 kilometres per hour due to a narrow curved section, while up to 30 kilometres per hour is allowed on straight stretches. The tram mechanics provide for automatic speed limitation through the switch, but this limit also depends on the working order of the on-board sensors, sources from the profession say.

GSP declined to answer media questions about when the specific switch was last inspected and whether earlier signals of problems existed. The statement says all relevant information will be provided to the competent authorities and released after the analysis is complete.

What does a technical expert analysis involve?

A technical expert analysis, which the prosecution orders in such cases, includes inspection of the tram’s black box with records of speed and braking forces, inspection of the traction bogie mechanics, geometric mapping of the rail line and switch, and analysis of the physical state of contact elements. The traffic expert appointed from the list of standing court experts at the Belgrade Higher Court will deliver findings that form the basis for the prosecution’s procedural decision.

The Ekoloski Ustanak party meanwhile demanded the resignation of the GSP leadership and the heads of the Secretariat for Public Transport, saying the accident raises broader questions about the state of Belgrade public transport. There has been no official reaction from the City Assembly so far.

Do you ride GSP trams regularly, and which line do you use most? Write to us about the conditions you observe.