Since 2008, the National Transit Database of the Federal Transit Administration has included extremely detailed urban passenger transport accident statistics.¹

The table below has been produced using data extracted from the National Transit Database: Safety and Security Time Series Data. ²

National Transit Database: Safety & Security Time Series Data

The table shows that whereas on average between 2008 and 2013, trolleybuses travelled 0.60% of the urban vehicle miles travelled by all buses, they accounted for 1.32% of the injuries to cyclists, and 2.20% of the injuries to pedestrians.

This means that a trolleybus is twice as likely as a motor bus to injure a cyclist, and three and a half times as likely as a motor bus to injure a pedestrian.

The following graph illustrates the much higher trolleybus injury rate.

Of the 571 trolleybuses currently operating in the United States (APTA 2012),³ just 119 or 20% are articulated vehicles, which suggests that some factor other than the length of the vehicle is responsible for the significantly higher injury rate of trolleybuses. A possible explanation for the higher injury rate is supplied by Barry J Simpson in Urban Public Transport Today (1994)⁴

“They are also much quieter than buses, which may be a blessing environmentally but can be a hazard to pedestrians, especially the blind, cyclists and others who may detect a bus coming from behind by sound rather than sight, hence their unfortunate nickname, ‘whispering death’.”

As well as being known as ‘Whispering Death’ in Australia, trolleybuses were known as ‘Silent Death’ and ‘Granny Killers’ in the UK.

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