Field and laboratory pavements were instrumented and load tested to evaluate the effect of lane widening, concrete shoulders, and slab thickness on measured strains and deflections. Eight slabs were tested in the field and two in the laboratory. Pavement slabs were 8- 9-, or 10-in. thick. Other major design variables included the width of lane widening, presence or absence of dowels, presence or absence of a concrete shoulder, joint spacing, and the type of shoulder joint construction. Generally, there was good agreement between measured strains and deflections and values calculated using Westergaard's theoretical equations. Concrete shoulders were effective in reducing the magnitude of measured strains and deflections. A chart is presented to show the reduction in thickness of the outer lane of the mainline pavement that may be permitted with a tied concrete shoulder.
