Shaped concrete barriers about 800 mm high, with a lower slope angled at 55 degrees to the horizontal and a nearly vertical upper slope, are used extensively in the usa on narrow central reserves and as bridge parapets, the most popular being the new jersey profile. Tests have shown that the new jersey profile does not overturn leyland mini cars which strike the barrier at a speed and angle of 90 km/h and 20 degrees appropriate to that which can be generated when a car veers across a two-lane carriageway. However at an approach of 113 km/h and 20 degrees, appropriate to a three-lane carriageway, a mini car was rolled over towards the barrier. Lowering the height of the new jersey barrier by 75 mm prevented rollover of the mini at 113 km/h and 20 degrees, so that this barrier shape, essentially the same as the american configuration f, is considered to be acceptable on most roads in the uk. Overlays of the road surface will minimise the benefits of the profile in casual impacts. When the new jersey barrier was raised 75 mm in relation to the road surface the results indicated that the leyland mini will rollover away from the barrier even at an approach of 90 km/h and 20 degrees appropriate to a two-lane carriageway. (Author/publisher)
Samenvatting