Sunday, March 25, 2018

Roadside Vegetation vs Wire Ropes

Much worldwide research suggests the aesthetic effect of roadside vegetation provides safety benefits to drivers.

In Europe and the USA, transportation psychologists are suggesting that safer driver behavior is generated by improving landscape and streetscape vegetation.

Studies in Canada and other countries show that streetscape improvements, including the planting of trees, reduced the frequency and severity of vehicle crashes.

“The presence of trees significantly dropped the cruising speed of drivers”.

“The addition of curbside trees significantly increased driver perception of spatial edge”.

Roadside vegetation can delineate the alignment of a road.
Could correctly selected and placement of roadside vegetation do a similar job to the wire rope barriers currently being installed along our freeways and major link roads – at considerable cost to Victorian ratepayers, ($120/m? VicRoads)?

Wire rope barriers are designed to stretch and absorb the force of impact and minimize the chance of rebound back onto the carriageway. There is some debate that roadside vegetation could achieve the same effect.

Costly? Effective (in reducing death & serious injury)
Studies by Monash University Accident Research Centre conclude that wire rope barriers significantly reduce deaths and serious injuries in crashes although there is some debate continuing in regard to their effect on motorcyclists.
Is the answer a combination of wire barrier and vegetation?
 Wire rope barriers do not reduce the frequency of accidents. World-wide research suggests that roadside vegetation does.

Further reading:
·         VicRoads Towards Zero – Flexible Wire-rope Safety Barriers Facts.
·         VicRoads Towards Zero – Roadside Management Strategy.
·         Landscape and Urban Planning – Landscape Improvement Impacts on Roadside Safety in Texas, (Abstract – “Environmental psychologists suggest that appropriately landscaped roadside scenes may have a reducing influence on travel-related stress or may improve attention…”).
·         Canadian Journal of Transportation – Roadside Aesthetic Appeal, Driver Behavior and Safety, (Abstract – In contrast with the assumption that roadside trees distract travellers from the driving task and thus add to collision risk, several studies actually support the notion that the presence of trees along the roadside has a calming and restorative effect on the state of mind of passing drivers and leads them to lower moving speeds.”).
·         US national Library of Medicine - The Effects of Clear Zone Size and Roadside Vegetation on Driver Behavior, (Abstract – “… studies have shown that natural landscapes can effectively lower crash rates and cause less frustration and stress to the driver.”).
·         The Arboricultural Journal – A Review of the Impact of Roadway Vegetation on Drivers’ Health and Well-being and the Risks Associated with Single-vehicle Crashes, (Abstract – “Roadside trees can help calm traffic, define roadways and reduce drivers’ stress.”).

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