摘要: |
On September 9, 1997, an ADEMII (Advanced Dynamic Impact Extension Module) was installed on Interstate 5 near Salem, Oregon. The ADEM II offered a redirecting, energy-absorbing crash cushion and end treatment for portable and permanent protection of concrete barriers. A three-person crew completed installation of the sloping concrete base and lightweight crushable concrete modules in about two hours.
This device was selected for use as an end treatment because of space limitations imposed by steep fill at the site. The Oregon Department of Transportation Research Group monitored the performance of the system for three years, particularly the weather resistance of the crushable concrete modules.
The modules developed soft spots after two years. An attempt was made to repair and re-coat the blocks. The new coating did not prevent soft spots. A corrugated plastic covering was also installed, and seemed to remain intact, though no analysis of the concrete inside the cover was performed. The lightweight concrete modules were replaced in October of 1999. The new modules were coated with a different type of water proofing material (Gama-Thane). By the spring of the following year a tear in the coating was found. In October 2000, one ADEM installation was damaged by vehicular impact, but seemed to work as designed in absorbing the force. The blocks were difficult to remove and replace, due to debris in the track in the sloping base, and to the twisting of the wire reinforcing.
ODOT has removed the ADEM from the approved product list for temporary applications. It is not approved by ODOT for use on permanent installations.
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