Thursday, April 7, 2011

I-70 High Maintenance

Close to home, I-70 near Georgetown was closed this last Tuesday due to mitigation of rockfall hazard.  Rock scalers were working for seven hours prying unstable boulders from the rock outcropping 300 feet above the highway near Georgetown.  To loosen the rock, the Colorado Department of Transportation (CDOT) used high-pressure airbags as well as other devices.  The boulders were caught in netting that was strung across the slope of the Georgetown Grade.  Georgetown Grade gets a significant amount of attention because of the heavy traffic volumes on I-70 below and it has an especially high slope that can send rocks down a long distance, building energy and momentum as it goes.

Source:Denver Post

For a short video that shows rocks being scaled click here

Scaling is done periodically to help reduce the risk of rockfall coming onto the highway.  By closing the highway and prying these boulders out, they will no longer be taunting I-70 commuters below.  About 30,000 motorists drive along I-70 at Georgetown Hill every day.  In 2003, a commuter was killed when a boulder crashed into his windshield.

After working on the site, CDOT announced that another rockfall mitigation technique may need to be done in the coming weeks.  Anchoring boulders may be done, if a solid section of the slope can be found.  This would mean another lengthly closure of I-70.

CDOT has placed netting along the slope face.  The goal of these nets is to progressively slow down falling rocks by letting them slip through the netting and roll to the next fence.  The rocks will loose energy this way each time they hit the netting.

The full article can be find here: I-70 reopens near Georgetown; intermittent closures planned Wednesday

1 comment:

  1. Thanks for this explanation--I always wondered about the nets. They didn't seem strong enough to contain the rock, so I appreciate knowing that they're meant to slow momentum.