An Assessment of Elsholz Redirective Concrete Kerb on Road Safety

Steel, Simon (2018) An Assessment of Elsholz Redirective Concrete Kerb on Road Safety. [USQ Project]


This dissertation focusses on a safety assessment of Elsholz redirective concrete kerb. Elsholz kerb is a road treatment approved for use in NSW, and has been used in place of safety barrier systems. Elsholz kerb is a low profile concrete kerb with protruding edges which cause a vehicle to redirect back into the travel lane when impacted, preventing the vehicle from crossing the kerb, and acting as a barrier. Elsholz kerb is gaining in popularity, with several projects in the Newcastle and Hunter regions of NSW using the kerb in recent years, despite there being very little information or research on this system. Elsholz kerb is included in the Roads and Maritime services standard drawings as a kerb profile, and is excluded from the list of approved safety barriers due to not conforming to Australian Standard AS3845.

The impact of Elsholz kerb on the safety of roads was assessed using crash data collected from sites in the Sydney Metropolitan area and Hunter region of NSW. 30 sites where identified and narrowed down to 9, removing sites which were not suitable. Reasons for removal included lack of data and installation of additional road features making Elsholz kerbs contribution to changes in crash profile impossible to determine. Both median and shoulder sites where considered. A cost benefit analysis was conducted using the equation provided in Austroads Guide to Road Safety, Part 8 (Austroads, 2015).

Elsholz kerb was assessed as having a positive impact on road safety, resulting in a reduction in crash occurrence and injury severity ratings. Total crashes where reduced by 61% following the installation of Elsholz kerb, reduced to 60% when all crashes not directly involving Elsholz kerb where removed. Installation also resulted in a reduction in speed factor crashes by 70%, along with a reduction in rear ends, indicating that it is deterring and slowing drivers, improving road safety. There is insufficient evidence to make a determination on the impact Elsholz kerb has on motorbike or heavy vehicle safety, due to limited data on these vehicles at the sites analysed. However, the limited data continues following installation, indicating that there is no evidence it possess an increased hazard to these road users.

Elsholz kerb reduced the occurrence of head on collisions by 81% across 6 median installations, a positive result, however research shows other systems, notably Wire Rope Safety Barrier, achieve superior results. Shoulder installation reduced off left crashes by 95%, however the analysis of this style of installation was limited by the number of suitable sites.

The Cost benefit analysis shows Elsholz kerb is financially viable as a safety improvement, achieving an average BCR value of 1.8 and total BCR of 4.8, using crash injury ratings and assumed construction costs. It should be noted Elsholz kerb requires no maintenance and is a low cost installation, contributing to these positive results.

In conclusion, Elsolz kerb has resulted in a positive improvement to the sites it has been installed on and there is no recommended change to the design practice concerning Elsholz kerb in NSW. Elsholz kerb cannot be considered a safety barrier, as it hasn’t been tested at higher speeds or angles, and did not exhibit all the expected attributes of a safety barrier. It should therefore be considered a kerb with redirective properties. Further research into Elsholz kerb, including a revision of this research at a later time and testing against AS 3845 standards is recommended.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours)(Civil)
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Drysdale, Trevor; Nataatmadja, Andreas
Date Deposited: 29 Aug 2022 05:08
Last Modified: 05 Sep 2022 02:33
Uncontrolled Keywords: Elsholz redirective concrete kerb; road safety

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