Note: the design suggestions from parks and greenways is on the Greenways page

A wonderful website how different species of trees will mature: Ohio Street Tree Evaluation Project

I'm not a designer. I'm an arborist. I'm more comfortable with the role of second guessing everything the designer suggests. After I complete my designer-sensitivity training and learn more about landscape designing I'll continue to add content to this page.

Design Conflicts

• The following is from "Introduction to CPTED" by the VA Crime Prevention Association (2002):
  • Design conflicts occur when two incompatible activities are located next to one another and are forced to compete for the same space. Sidewalks for elderly housing that take residents by teenage recreation areas may cause the elderly residents to feel intimidated by rough play they see, even though no direct threat is intended. A liquor store located on the same corner as a bus stop for a nearby residential community can create problems for the residents. The design conflict forces residents using the bus to deal with the disruptive behavior often found around liquor stores. An extreme example of a design conflict would be an adult book store located across the street from a child day care center or a domestic violence shelter. 
  • Design conflicts can expose users to crime or raise their levels of fear about crime. Competition for the same space can lead to disputes which can escalate to serious assaults. Design conflicts usually have the greatest impact on those who have limited ability to defend themselves: the elderly, young children or the handicapped. These users are then likely to avoid these locations because of fears for safety. Design conflicts can cause legitimate users to avoid a location and consequently give it up to illegitimate or disruptive users.

A designer/planner is working in a vacuum if he designs a space without knowing the intended user or how the intended user will use the space. Crowe (2000) has a good model (Three-D Approach) to help the designer assess a space before making fateful decisions.

Like any long-term project, the designer should carefully plan out the entire landscape and then proceed with the project in stages. 

Residential Landscape Design
Dig out your property plat and trace over that to develop your "base map." Note the height of your house and other large structures on your base map. You'll need to imagine what your proposed landscape will look like in three dimensions. Mark areas on your house that receive sunlight and shade. Next, indicate where you would welcome full sun, partial sun, and/or shade on your house and other key areas in your landscape. Using large circles, or ovals, identify the difference "spaces" (for more information on spaces click on Introduction) on your landscape that will have a distinct purpose. Install structures like decks, gazebos, and benches to provide points of natural surveillance throughout your property. Deciding upon where to install paths will allow you direct access control to your residence. Consider installing a small hedge or row of vegetation to establish clear lines of territoriality in areas where there may be potential confusion.   

I recommend planting the trees that will become your large shade trees first. Next, you may wish to construct hardscape features such as walks, decks, gazebos, retaining walls, etc. Contact a consulting arborist or certified arborist with experience in preserving trees during construction activities to install a fence around the trees you wish to preserve.  

The spirit of CPTED is that the property owner actively designs out crime. Don't inadvertently design in conflicts. The following list captures just a few potential conflicts: 

• Natural Surveillance
  • Make sure future plans will NOT include the installation of structures or vegetation that will block natural surveillance. 
  • Stand in the house (building, structure, etc) and identify important sight lines from doors and windows. Go back to the landscapes plan and imagine what the proposed vegetation will look like when it's mature. Don't assume the trees and shrubs will be routinely pruned. Good intentions don't get much done around my landscape. Establish a contract with a local landscape maintenance company and formally request that they perform annual vista pruning to maintain specific sight lines.
  • Design outdoor sitting areas. Carefully consider details like placement of benches to maximize sight lines. Be sure to make use of natural features like subtle differences in the elevation of the land when selecting the sitting areas.
  • Avoid creating outdoor living spaces that are near vents or noise generators.
  • Keep in mind the intended user's senses. Attempt to design in factors that the intended user will enjoy. 
• Territoriality
  • When designing with territoriality in mind think maintenance. Anticipate places in the landscape which receive little traffic and attention. Select plants which require little maintenance for these potentially neglected areas.
  • Enclosed areas and corners act like magnets for collecting leaves. Observe wind patterns and attempt to install a low growing hedge to prevent leaves from collecting in these enclosed spots. During wet weather these areas present a serious slip hazard.
  • Since color influences human behavior, consider working in red for areas where activity is beneficial and blue for areas where users may just sit and relax.
• Access Control
  • When designing a space around a large growing shade tree be aware of the tree's natural branching habit. Excurrent trees, like pin oaks and willow oaks, orient approximately one-third of their limbs in a downward direction. This presents a real threat to pedestrians and landscapers attempting to walk under these trees. In areas where the lower canopy of shade trees may hinder natural surveillance or possibly harm pedestrians, consider installing a tree with upright branching (decurrent trees). Please see Plant Selection for additional suggestions. 
  • Carefully consider each space in your landscape to see if it clearly communicates to potential visitors how they should enter, leave and move around on your property. Often times signage and symbolic barriers will be sufficient at directing vehicular and pedestrian traffic. Low growing hedges, low walls, and even flower beds direct traffic and allow for natural surveillance and can still define a space. Tall hedges and high walls may be good at providing access control but separate a space and block natural surveillance. 

Change Is Inevitable
It's important to re-analyze the purpose of spaces on a regular basis because of changing land use, commercial districts, parks, ethnic make-up of neighborhoods. Question everything, the original intent may no longer be applicable.

Public Spaces: Build It and They Will Come...
When you are not certain about the intended activity or pedestrian traffic patterns consider making preliminary landscaping plans with the building. After the building is open carefully observe the intended users to see what space they claim and what activities they prefer. Then complete the landscape to support these intended users and remove potentially underused areas which would of been claimed by undesirables. 

Ordinances
Due to significant changes which have recently occurred in the fields of crime prevention, arboriculture and urban forestry all ordinances pertaining to vegetation in urban areas should be re-evaluated. Wording in ordinances should be changed to reflect our understanding of how trees respond to pruning and construction. In order to maximize the benefits of urban forests more emphasis should be placed on the maximum height of trees, and not minimum height at time of installation. Wording should be changed to reflect the overall objectives and not to provide detailed directions. For example, it would be better to word a job description as raise crown height for a 10 foot clearance over the parking spaces and 8 foot clearance over sidewalk instead of calling for raising limb height. Since the majority of trees fail due to soil related problems more attention should be directed to soil testing and necessary adjustments prior to tree installation.   

References

Crowe, T. 2000. Crime Prevention Through Environmental Design: Applications of Architectural Design and Space Management Concepts. Second Edition. National Crime Prevention Institute. Boston: Butterworth-Heinemann

Sunset Books. 1984. Sunset Landscaping Illustrated. J.K. McClements & S, Fitzgerrell. Menlo Park, CA: Land Publishing Company

Virginia Crime Prevention Association. 2002. Introduction to CPTED. Manual used in Introductory CPTED training. May 2002.