Bicycle Helmet Safety Institute

Bicycle Helmet Safety Institute

The Helmet Update

Volume 41 - #2 - January 31, 2023

All issues index

Serbian study concludes drivers pass helmeted ebike riders closer

A new study conducted in Serbia presents research on ebike passing clearance on a Serbian road. An orange-shirted ebike rider recorded passing distances with the jersey, an added vest or helmet, or both at various ebike speeds. The study also covered the type of vehicle passing. It reached some conclusions that you will hear about for decades:

• "The results of the interaction between speed and the category of the vehicle overtak- ing the e-bicycle lead to the conclusion that for all three tested speeds, there are statisti- cally significant differences between two vehicle categories: motorcycles (the shortest lat- eral distance) and heavy goods vehicles (the greatest lateral distance). On the other hand, the interactions between the protective equipment and vehicle category, speed, and pro- tective equipment, as well as the interaction between speed, protective equipment, and vehicle category, show no statistically significant effect on the lateral distance when over- taking an e-bicycle."
• " The results of the t-test showed statistically significant differences between the lateral distance when overtaking an e-bicycle and the use of helmets (t = 5.489; p = 0.019). When the e-bicyclist wore a helmet (the average lateral distance when overtaking e-bicyclists with helmets was 1.17 m), vehicles overtook him at shorter lateral distances than when he did not wear the protective helmet (the average lateral distance when overtaking e-bicyclists without helmets was 1.51 m" (Remove the context above and this will make the headlines: passing clearance of 46" vs. 59".)
• "The faster the speed of e-bicycles, the shorter the lateral distance between the overtaking motor vehicle and the e-bicycle being overtaken."
• Shortest passing clearance: motorcycles .8 meter (31"). Longest: heavy trucks 2.06 meters (81").
• Bottom Line: Since passing clearance lessens when ebikes ride faster: "Therefore, in the countries where the use of protective helmets is not compulsory, e-bicyclists should still wear them."

Caveats: This study was conducted on a two-lane Serbian road unlike any in the US. The drivers were probably mostly Serbian. Lane width was a nominal 3 meters, but varied. Speed limit was 50kph (32mph). The rider positioned himself exactly .5 meter from the edge of the roadway, although in the Walker study there was no passing clearance difference when the rider was one meter from the edge. (Serbian law prohibits riding more than one meter from the edge.) The rider wore a long-sleeved bright orange jersey with or without vest and helmet. The helmet was dull black and not very visible, so drivers may not have been aware of it at all when contrasted with the attention-getting orange jersey and/or hi-viz yellow vest.

Since we are still seeing naive articles citing the discredited 2007 Walker study this one is likely to come up for years.

You can read the entire study online with no charge.
"Analysis and Determination of the Lateral Distance Parameters of Vehicles When Overtaking an Electric Bicycle from the Point of View of Road Safety" Applied Sciences 13, no. 3: 1621. https://doi.org/10.3390/app13031621 January, 2023.