It’s not uncommon for tree roots to cause damage to sidewalks in Broward County, FL. The problem of tree roots lifting sidewalks is evident in every major city in Broward County, FL. Tree roots damage sidewalks by raising individual sidewalk slabs and by cracking sidewalk slabs. The questions that arise are how to stop tree roots from damaging sidewalks, and what to do when tree roots have already damaged a sidewalk.
Cities in Broward County, FL, and throughout the country, are sensitive to tree roots that damage sidewalks because of potential liability issues that go along with damaged sidewalks. Obvious tripping hazards put cities at the risk of a lawsuit, but the continued cost of repairing sidewalks puts a strain on city budgets.
SIDEWALK DAMAGE FROM TREE ROOTS
The best way to stop tree root damage to sidewalks is through proper planning. A tree species that is going to grow large is also going to produce a significant root system to support the tree. Planting a large tree species in the narrow strip between the road and sidewalk is asking for future problems with tree roots and sidewalks. Cities in Broward County, FL know this because they spend thousands of dollars fixing sidewalks damaged by tree roots.
So, should cities in Broward County, FL only plant small tree species between the road and sidewalk? Although this may be a viable solution, city foresters want to incorporate a variety of tree species in their urban forest and it is nice to see a street lined with large, mature trees. Mature trees impart many positive social and economical benefits to a neighborhood. Maybe city foresters could take a different approach needs to the management of trees between the road and sidewalk.
The current philosophy in most cities in Broward County, FL is to not remove the tree, but to just eliminate the tree roots damaging the sidewalk. How are offending tree roots eliminated? Sometimes the tree roots near sidewalks are chopped out with an axe, or the tree roots might be pulled out with a backhoe, or the city might use a stump grinder to grind out the offending tree roots near a sidewalk. All of these methods place the tree, and city residents, at risk in two ways. Cutting large tree roots can affect the stability of the tree. The next windstorm might cause the tree to be blown over after the root cutting has been done. Cutting large tree roots near a sidewalk might also lead to decay fungi entering the tree. The end result of this will also be a fallen tree at some point in the future. Cutting large tree roots is usually a temporary fix to the problem. The roots will be cut, a new sidewalk will be put in, and then the tree will grow new roots to damage the new sidewalk. Every time root cutting is done the chances of the tree being blown over, or decay entering the tree, increases.
Oftentimes, the effects of cutting tree roots are not immediately apparent. Deciduous trees have stored food reserves and will compensate for damage done to the tree roots. Even though the tree looks healthy it does not mean significant structural damage has not been done to the tree. Just as it can take years for a tree to become large, it can take years for the effects of root damage to become evident.
Should a city create potentially hazardous trees by cutting large tree roots, or just remove the trees for the safety of city residents? This choice can put a city forester in a no win situation. Removing a mature tree can be an unpopular option with city residents even though the overall liability to the city may be reduced by removing the tree instead of cutting larger roots. The city forester must consider if the liability of the trip hazard caused by a raised sidewalk may be outweighed by the damaged caused by cutting large tree roots. Cutting large tree roots away from sidewalks now may cause future problems greater than the current liability if the entire tree falls over. The fallen tree may damage property, injure or kill a city resident, and will likely damage the new sidewalk. Instead of continually damaging and weakening a mature tree by cutting large roots the tree could be removed and a new tree planted to replace it.
There are several things that could be done to extend the useful life of trees planted between the road and the sidewalk. Root barriers can be installed to prevent or redirect root development near sidewalks. Foam has been used below sidewalks as an underlayment for the sidewalk. The foam gives support to the concrete and will compress to accommodate diameter growth of tree roots. Alternatives, such as rerouting the sidewalk around encroaching tree roots should be used whenever possible. Most other alternatives, such as, adding asphalt to raised edges, grinding down raised edges, or re-pouring the concrete to create a mounded sidewalk are short term fixes. The tree roots will continue to increase in diameter and quickly lift the sidewalk again
Another alternative would be to view the urban forest with a crop rotation approach. If large tree species are going to be planted it can be done with the knowledge that removal and replacement of the trees will be done if sidewalk damage starts to occur. Some city residents would be upset, but continually replacing sidewalks, and damaging trees in the process, can be a strain on any city budget. Although most urban foresters would be able to relate to this long term view, convincing some city residents that this is the right approach could be difficult.
Most urban foresters, and city residents, would prefer to not remove mature trees. But at what price should a city adhere to this type of policy? City foresters must either work around the normal growth pattern of the tree or consider removal of the tree. Continually cutting large tree roots will eventually result in a large fallen tree.