Past field studies of lateral distribution of trucks on highway pavements are limited in their relevance to current design practicesand truck size limits. In particular, little information is available on the effect of widened concrete slabs on lateral distribution of trucks. The illinois department of transportation has constructed test sections of "widened-lane" pavements with 18-in. And 20-in. Slab extensions on i-57. Truck wheel placements on these test sections were compared with those observed on nearby conventional 12-ft pavement slabs in a recent study conducted at the university of illinois.Continuous filming of truck wheel positions was performed with an 8-mm camera mounted on bridges over the highway. Wheel positions weredetermined to within approximately 0.5-In. Precision by scaling distances measured on the films to known dimensions on the pavements. The mean placement of the wheels of over 900 trucks observed on the control sections was about 22 in. From the slab edge. About 2.5% Of the wheels passed within 6 in. Of the slab edge. On the widened-lane sections, the mean placement of truck wheels was about 2 in. Closer to the lane edge (marked by the paint stripe) but still 38 to 40 in.Away from the slab edge. No slab edge loadings were observed among more than 1, 300 observations of truck wheel placements on the widened-lane pavement sections. The results suggest that lane widening is likely to be a cost-effective design improvement for concrete highway pavements that otherwise would be vulnerable to transverse fatiguecracking as a predominant mode of failure. This paper appears in transportation research record no. 1286, Design and evaluation of rigid and flexible pavements 1990.
Samenvatting