Big trees enhance urban areas, but we need to find ways to make them compatible with sidewalks. Under Pottstown ordinances, adjacent property owners are responsible for the care and maintenance of sidewalks. Trees are a significant cause of lifted sidewalks, but there are a variety of other reasons including: freezing and thawing weather, sewer lines settling, improperly poured concrete, and exposure to the elements. Trees lift sidewalks when their roots grow within 8 inches of ground level. All trees are shallow rooted, but it is almost impossible to predict when tree roots will rise to the surface. The chief reason trees lift sidewalks is the inadequate size of the tree well (the planting area cut into the sidewalk). Trees Inc. now attempts to enlarge wells to 4 or 5 feet by 10 or 12 feet when planting new trees and recommends property owners do the same when replacing sidewalks.
Better even than large tree wells is the "tree lawn" or "boulevard." This is a strip of grass between the curb and sidewalk that give roots room to grow. Tree lawns are used in many "neo-traditional" developments across the country. Pottstown now promotes tree lawns in all new developments, such as May Street crossing.
As of May 2010, property owners may use asphalt to repair or replace sidewalks affected by street trees. For a copy of the new ordinance, click here.
A much more traditional sidewalk material – brick – is more compatible with trees than concrete. Brick has been used as sidewalk material for hundreds of years. Pottstown has scores of brick sidewalks, some dating back to the late 18th century. Brick is much more compatible with trees because they allow more water to penetrate into the ground, encouraging deep root growth.
When roots do lift a sidewalk, it is a simple matter to pick up the bricks, chop down the root 3 or 4 inches below ground level and re-lay the brick. Slate sidewalks are similar to brick because they can be lifted up to gain access to the roots. Once the tree roots are cut back to provide sufficient clearance, the slate can be re-laid.
In 2006, Trees Inc. received permission from the borough manager to pour an asphalt sidewalk over a large tree root on Cherry Street as an experimental project. The asphalt was then painted with a quick-dry traffic marking paint designed for asphalt. Several other asphalt sidewalks were then installed on West Second Street. Over time, the paint will darken to better match the original concrete. Creativity can make it possible to provide shade and greenery even in the most crowded urban areas and still make sidewalks safe for walking.