Balancing Roadside Tree Benefits and Risk of Streetscape Tree Crashes

Summary: An article in Arboriculture & Urban Forestry March 2019 assesses balancing benefits of roadside trees against risk of streetscape tree crashes.

an extreme example of a streetscape tree crash: BBC News (UK) @BBCNews via Twitter Dec. 16, 2018

An article in Arboriculture & Urban Forestry March 2019 associates the risk of streetscape tree crashes with the "probability of an event occurring and the consequence of the event should it occur."

Co-authors Ethan Allen, George Fitzpatrick, Andrew Koeser, Michael Olexa and Jeffery Van Treese II broach appealing, pleasing, stress-reducing, value-added tree-lined roadsides when target-struck by tree failure. Streetscape trees correlate socio-economically with output state expenditure and value-added capital consumption, income, indirect business tax and wage impacts and with fixed-object crashes in run-off-road accidents. Roadway conditions, design and geometry and vehicle weight determine the relative risk of streetscape tree crashes, whether roadside trees dispense hazardous tree failures or roadway definitions.

Guardrail leading ends, streetscape trees and utility poles enhance probabilities of fatal injuries in fixed-object crashes even as constrained, enclosed, smaller streetscapes encourage less risky driving.

Fixed-object crash severity fetches no injuries; minor bruises, lacerations and scrapes; major disabilities and incapacitations, including fractures and severed limbs; or fatal injuries within 30 days.

The article Frequency and Severity of Tree and Other Fixed Object Crashes in Florida, 2006-2013, gauged streetscape tree crashes at 14.6 percent of 323,581 single-vehicle crashes. Rural and urban settings respectively harbored streetscape tree crashes as the second and third commonest crash types, as 15 and 14.2 percent of their crashes, 2006-2013. Predictor variables of daylight, dark, dark with lighting and dawn/dusk identified streetscape tree crashes as respectively 10, 8.2, 23.1 and 9.8 percent of 323,581 single-vehicle crashes.

Streetscape tree crashes juggled respective frequencies of 14.29, 9.48, 6.8, 4.48 and 3.73 percent in single-vehicle crashes in severe crosswind, low-visibility, clear, rainy and cloudy weathers.

Severity analysis by no, minor, severe and fatal injuries knew respective frequencies of 46.6, 40.8, 10.8 and 1.7 percent of 7,341 total streetscape tree crashes, 2006-2013.

Of barrier, ditch, fence, no-fixed-object, pole, rollover, sign, structure, tree and water single-vehicle crashes, signs and structures logged far less severe levels than streetscape tree crashes. Rollovers manifest likelihoods of increased severity levels 1.5 times that of streetscape tree crashes and model 6.1 and 14.72 percent of rural and urban single-vehicle crashes. Narrow clear zones and lane widths on high-speed rural and low-speed urban roadways and large-zoned, wide-laned urban roadways net respectively high-frequency and low-frequency streetscape tree crashes.

Planters, trees and low-speed wide lanes respectively occasion fewer mid-block and urban run-off-roadway, greater rural run-off-roadway and, with increased driveway and pole density, greater single-vehicle crashes.

Streetscape tree crashes presented 1.5 and 3.5 percent of 3,033,048 crashes and of road fatalities recorded by the Florida Department of Highway Safety and Motor Vehicles.

The eight-year period queued up 94 yearly deaths in tree-related crashes and 15,464,241 licensed Florida drivers, for a 1:164,513 risk of harm in streetscape tree crashes. The National Safety Council and the Quantitative Tree Risk Assessment reveal respective risks at 1:9,008 and 1:1,000,000 for all United States motor vehicles and in arboriculture. National Safety Council statistics show 17-year spikes by 6,113 and 15,080 in deaths from respiratory and cardiovascular illnesses where excessive tree removal signifies lost tree canopies.

One Florida Atlantic University and four University of Florida researchers tether risk of streetscape tree crashes versus benefit to removing high-risk, low-value, not low-risk, high-value, trees.

A streetscape tree crash damages both the tree and the vehicle; Karrinyup Road, Stirling, West Australia, western Australia; March 27, 2012: perthhdproductions, CC BY 2.0, via Flickr

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

an extreme example of a streetscape tree crash: BBC News (UK) @BBCNews via Twitter Dec. 16, 2018, @ https://twitter.com/BBCNews/status/1074263371007037440

A streetscape tree crash damages both the tree and the vehicle; Karrinyup Road, Stirling, West Australia, western Australia; March 27, 2012: perthhdproductions, CC BY 2.0, via Flickr @ https://www.flickr.com/photos/perthhdproductions/7471223692/

For further information:

BBC News (UK) @BBCNews 16 December 2018. "Shrewsbury crash leaves car vertical in tree." Twitter.
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