A new Interstate 95 mural by renowned children’s author and illustrator David Macaulay has been defaced by graffiti. The mural in Providence was completed in June as part of a highway beautification project aimed in part at reducing vandalism. It is one of two highway murals designed by Macaulay, who attended the Rhode Island School of Design. Red graffiti covers the length of the mural. Rose Amoros, spokeswoman for the state Department of Transportation, said Wednesday that crews will be working through Wednesday to clean it, although they are having trouble. Once they remove the paint, she said they will restore it.