Hedges are a great thing.  They define properties, keep out the neighbors' dogs (but probably not the neighbors' cats) and provide a nice backdrop for a garden.  Recently there has been a vogue for mixed hedges, where several different types of shrubs alternate to form one line of greenery.  Mixed hedges add interest and enhance horticultural diversity.

Whatever kind of hedge you choose, make sure that you provide enough room between the young plants and the sidewalk.  Look at the planting tag on the shrubs of your choice to see how wide they are likely to be at maturity.  If a particular variety will be four feet wide at maturity, for example, be sure to plant it more than two feet from the sidewalk.  Otherwise it will end up as a man (or woman) eating shrub, obstructing part of the sidewalk and making it impossible for people to pass each other or walk two or three abreast without treading on the grass or other plantings on the street side of the sidewalk.  Needless to say, if enough people are forced to do that on a daily basis, the grass or plantings will not survive.

But what do you do if you or, more likely, the previous owner of your house, planted the shrubs too close to the sidewalk?  Taking them all out is too draconian in most cases.  However, you can make sure that your shrubs are closely and regularly clipped on the street side.  You can also move the shrubs back gradually, starting on one end, cutting one or two of the shrubs way down, digging them up and then replanting them a foot or two back.  Your hedge will look a little unusual for a few years, but eventually it will be tamed.  Be sure to do your transplanting in the spring or fall, when the shrubs will not be stressed by extreme temperatures.  Provide plenty of water to your transplants and they should be fine.