slot sawing machine might not be feasible. Consider allowing the use of walk-behind saws for slot cutting when the project contains fewer than 100 retrofit bars. Remove existing concrete from the slots followed by the cleaning out of all debris. Use maximum weight 30 pound jackhammers to remove the concrete remaining between the saw cuts. If the concrete removal operations cause damage to the pavement that is to remain, discontinue concrete removal operations and only resume after taking corrective measures. During concrete removal operations, use a small bush hammer as necessary to produce a flat, level surface within the slot so the backfill flows and consolidates under the dowel bars. Complete installation of retrofit dowels, with dowel bars and backfill placed prior to reopening the lane to public traffic. Place silicone at all joints and cracks followed by the dowel bar assemblies in each slot. Following that, place patching material and then consolidate and finish patching material. Finally, diamond-grind the pavement surface within 30 working days of dowel bar retrofit placement. Problems Dowel bar retrofits, if done badly, can cause serious problems. These problems are usually due to poor workmanship and can be avoided by careful following of specifications and close supervision of workers. Use of heavy jackhammers (heavier than 14 kg class) tends to cause cracking of the concrete all around the slots. Lack of caulk or voids in the caulk put in the joints or cracks leads to cracks around the joints. Voids in the grout (especially below the dowel bar) can cause failure of the grout. Confusion with road surface markings The completion of the dowel bar retrofit process usually leaves marks on the concrete pavements which consist of short parallel lines in two groups, left and right, inward the traveling lane from the lane markings. Each group has 3 or 4 slots that are parallel to the traffic flows. Each rectangular slot has the width of about and the length of about or more. The backfilled slots may sometime give an impression that the highway pavements have been milled into grooves especially after the wear of patching material caused by studded tires. The visible marks may appear to be a symmetrical pattern of dash marks on the roadway, as if there were an associated meaning to the pattern. When there are many of them along the roadway, motorists on the interstate highways may interpret the grind