EMPIRIcAL fINDINGS ON STREET TREES AND ThEIR EffEcT ON DRIVING BEhAVIOR, SAfETy PERcEPTION AND SPEED. ThE ExPERIMENT INVESTIGATED ThE EffEcT Of TREES ON PERcEPTION Of SAfETy AND DRIVING SPEEDS IN URBAN OR SUBURBAN SETTINGS. TREE-LINED STREETS WERE PERcEIV

Street trees are dangerous, difficult to install and expensive to maintain, but there is not a transportation engineer who has not had to negotiate tree planting or tree preservation to reach project comple-tion. Engineering design and transporta-tion planning guidelines consider street trees obstacles in the roadside environ-ment. Transportation research related to street trees in the United States focuses on fatal off-road crashes. Although much of this research is highway focused, it im-pacts the roadside environment of arteri-als and collectors as well. Although there is an historical aversion to invest in the installation and mainte-nance of street trees from an operational perspective, the multimodal traveling pub-lic loves them. U.S. National Cooperative Highway Research Program Project 17-18(3) summarizes the street tree issue facing transportation engineers: “A complicating factor in addressing fatal tree crashes is the widespread interest and indeed promotion of tree-planting and preservation associated with highways. ” 1 This is even more true with the local network. In the United States, the “no trees” guidelines are housed primarily with th