Tweet Check

Welcome to RAIL’s new fact-checking service, which aims to answer your questions, debunk the myths, and get to the unvarnished truth behind some of the most common claims and queries we spot on social media.

Balloons present inflated risk to trains?

RAIL’s verdict: When our long hot summer eventually begins to turn to autumn, and trees start to shed their leaves, we expect to be subjected to reminders of the infamous and much-ridiculed phrase that delays have been caused by ‘leaves on the line’.

But balloons on the line is a new one altogether for the RAIL team. Incredible as it sounds, a Govia Thameslink Railway spokesman confirmed that the offending object blocked the Down Fast line to the north of King’s Cross for a full hour and a half at the start of the evening peak on July 30, after becoming caught in overhead lines.

With one of two northbound tracks out of action for electric trains, 70 services were delayed for a total of more than 600 minutes, while Network Rail engineers raced to the scene and presumably took a pin to it.

It certainly sounds like a load of hot air, and perhaps even blown out of all proportion, so we asked the Network Rail press office to provide a plausible technical explanation.

Spokesman Jack Harvey said: “This is a common cause of delays - not necessarily balloons, but during high winds we suffer from plastic bags and other debris blown on the overhead line system. Unfortunately, this incident happened at a busy time near a major station.

“The risk is that the debris might entangle in the train’s pantograph, which could further snag on the overhead line equipment with the potential to damage the infrastructure or the train.

“Although the risk is low, due to the potential consequence of a de-wirement, NR does not tolerate the risk - especially in public areas such as a station.”

Harvey added: “Usually the debris will be removed using a live-line pole. There are other options available, such as trains lowering their pantographs and coasting under the object, but this option might not have been available due to the proximity of the station.”

RAIL contributor and track specialist Gareth Dennis surmised: “Unlike a fallen branch, which usually gets blasted straight off the wires, a balloon probably gets tangled or melted into the contact and catenary, causing a current fault that prevents the system from being activated safely. This requires an isolation and someone to clear the fault to confirm it wasn’t a person.”

Balloons on the line, therefore, would seem to be no laughing matter.