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Neighborhood Traffic Calming Policy and Guidelines


Introduction

Traffic calming presents a new dimension when discussing the use of public rights-of-way. The goals of traditional transportation improvements have focused on capacity, speed and safety. While these are still concerns another dimension is often added, that being the dimension of maintaining or restoring the "livability" of a neighborhood. This new dimension is what is referred to as "traffic calming". Traffic calming has many names, traffic mitigation, neighborhood traffic management, and neighborhood traffic control to name a few. The City of Delray Beach will use the Institute of Transportation Engineers (ITE) definition for traffic calming, which is:

"Traffic calming is the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users."

The major difference between traffic calming measures and other forms of traffic control devices, such as stop signs and speed limit signs, which require enforcement, is that calming measures are self-enforcing. Also, traffic calming should rely on the laws of physics rather than human psychology to slow traffic. Although certain features along the rights-of-way such as street trees and other streetscaping may be intended to aid in calming traffic, there is no evidence indicating that these features directly induce drivers to slow down. Finally, route modifications, such as street closures and walling off communities are considered to be outside the realm of traffic calming since these modifications imply that public streets are now private, when in fact they still are public rights-of-way.

The City of Delray Beach is committed to ensure the overall safety and livability of residential neighborhoods. One way to meet this commitment is through a collaboration of City staff, residents and other agencies in an effort to minimize the impact of traffic on neighborhoods. The City of Delray Beach Neighborhood Traffic Calming Policy and Guidelines provides a process for identifying and addressing problems related to speeding, excessive volumes, and safety on neighborhood streets.

This Traffic Calming Policy and Guidelines will put into practice the objectives and policies contained in the Transportation Element of the City of Delray Beach Comprehensive Plan. These include:

  • Special attention shall be paid to documented high accident areas, and specific activities shall be undertaken to reduce their occurrence.
  • Travelways, which are primarily used by residents (local streets), shall receive special attention in order to assure that they remain accessible to residents and provide for easy traffic flow.
  • Efforts shall be made to limit excessive through-traffic and nonresidential traffic on local roads within neighborhoods. Where a problem such as traffic is specifically identified, it should be addressed through the utilization of traffic calming measures, such as roundabouts, medians, and speed humps.

In short, this policy provides a procedure to consider, evaluate, and implement requests for traffic calming measures within the City of Delray Beach.

Definitions

  1. 85th Percentile Speed - that speed at which 85% of the free flowing vehicles are traveling at or below.
  2. Arterial Street - a heavily traveled street of considerable continuity used primarily as a main traffic artery. Ideally, an arterial street would have restricted access and provide a high degree of mobility and continuity. See Figure A
  3. Collector Street - any two or four lane street which links an arterial street with another collector street of local street. See Figure A
  4. Defined Neighborhood Boundaries - the boundary of the problem area, which may cross traditional neighborhood boundaries.
  5. Emergency & Evacuation Routes - routes identified, usually with a classification of a collector or above, that are identified as key routes for emergency response. See Figure B.
  6. Local Street - any two lane street with a primary purpose of providing direct access to abutting residential properties.
  7. Residential Cut-Through Traffic - traffic which uses local or collector streets to travel through a residential neighborhood without having an origin or destination within the neighborhood.
  8. Speed Study - a study using equipment to measure, collect, and statistically analyze the speeds of vehicles.
  9. Traffic Calming Measure - an element of a traffic calming plan selected from among those devices authorized herein for use within the city.
  10. Traffic Calming Study - an appraisal of traffic conditions and the development of a plan for implementing one or more traffic calming devices in a residential neighborhood.
  11. Traffic Count - a manual or automated count of the number of vehicles traversing a particular street in a given time period.

Objectives

The overall objects of the Traffic Calming Policy and Guidelines are derived from the existing objectives and policies contained in the Transportation Element of the Comprehensive plan mentioned earlier. The overall objectives include:

  1. Maintain and/or improve neighborhood livability by mitigating the impact of vehicular traffic on residential neighborhoods.
  2. Promote safe and attractive streets that maintain and/or improve the quality of life in neighborhoods.
  3. Promote conditions that provide safe neighborhoods for motorists, bicyclists, pedestrians and residents of the neighborhood while maintaining access to the neighborhood.
  4. Encourage citizen involvement in all phases of neighborhood traffic calming activities.
  5. Make efficient use of City resources by prioritizing traffic calming requests.
  6. Support the policies contained in the Transportation Element of the Comprehensive plan.
Policies


The following policies are established as part of the Neighborhood Traffic Calming Policy and Guidelines:

  1. Through traffic should be encouraged to use higher classification streets (i.e. collector and arterial streets), as designated in the Transportation Element of the City of Delray Beach Comprehensive Plan.
  2. Traffic may be re-routed from one street to another of equal classification as a result of a neighborhood traffic-calming project, if and only if the end result is a more equal distribution of the traffic volumes. However shifting a traffic problem from one street to another or one neighborhood to another is not an acceptable alternative.
  3. Reduce the average speed of motor vehicles within neighborhoods.
  4. Implement cost-effective measures for solving identified traffic problem(s).
  5. Improve real and perceived safety for non-motorized users of the rights-of-way.
  6. Reasonable emergency vehicle ingress/egress must be preserved.
  7. Reasonable automobile access should be maintained. Calming measures implemented should encourage and enhance pedestrian and bicycle access to and throughout defined neighborhood.
  8. Any local residential street can qualify to have calming measures implemented. Collector streets will be considered on a case by case basis. Arterial streets will not be considered for traffic calming measures. Street classification is designated in the Transportation Element of the Comprehensive plan. See Figure A
  9. The City shall employ traffic calming measures to achieve the objectives identified in this document. Traffic calming measures include, but are not limited to those measures listed in Section X. The City Engineer shall direct the design and installation of all calming measures along with the traffic control devices (signs, markings, etc.) as needed to accomplish the project, in compliance with the municipal code.
  10. In processing and implementing traffic calming requests, certain procedures should be followed by the City to ensure that applicable codes and related policies are adhered to, and that projects are within the limits of available resources. At a minimum, the procedures shall provide for submittal of project proposals; project evaluation and selection; citizen participation; and communication of any findings related to the proposed project. All projects shall receive input from area residents and affected organizations, and appropriate City Commission approval before installation of permanent traffic calming devices.

Process

Project Requests and Initiation of Traffic Calming Study

Requests for a traffic calming study, which are usually volume and speed related, can be requested through one of the following:

  1. Homeowners Association - a study may be initiated upon receipt by the city manager of a petition  signed by at least one member of sixty-six percent (66%) of the households facing the block(s) of the street on which the Traffic Calming Study is requested. A block shall consist of every developed property having frontage on the street to be studied between successive intersecting streets. A typical Traffic Calming Petition shall include, at a minimum, a description of the street or streets which are to be included in the calming study and the signature of at least 66% of the residents living on those street(s).
  2. Non-public safety project requests shall require an application fee of $100.00.
  3. Public Safety or City Staff - a study may be initiated because of an identified public safety
    issue.

Phases of Traffic Calming Study

Before any neighborhood traffic problem, whether real or perceived, can be addressed, it must be understood. The following outlines the various phases involved in a traffic calming study.

  1. Citizen Meeting - All Traffic Calming Studies shall begin with an open meeting, organized by Community Improvement Department, to which all potentially affected residents are invited. An overview of what traffic calming is, what it is intended to do and what criteria are used in selecting traffic calming devices and location(s) will be discussed, as well as an opportunity for residents to provide comments. Staff will work to define neighborhood boundaries.
  2. Data Collection Phase - Once the defined neighborhood is identified, appropriate "before" data will be collected. Data collection strategies will be discussed to determine the appropriate type of data to be collected as well as length and dates of collection. Data collection before any measures are implemented also serves as a comparison to "after" data to determine the effectiveness of the traffic calming measures. Table 1 lists typical data that could be collected for each defined neighborhood. If additional data is needed for a defined neighborhood, the appropriate study will be conducted to supplement the above information.

Ranking projects
A rating system, see Table 2, will be utilized in order to enable competing local street traffic calming projects to be ranked in relation to the anticipated benefit. Similarly a rating system, see Table 3, will be utilized in order to enable competing local collector street traffic calming projects to be ranked in relation to the anticipated benefit. If multiple projects are competing for traffic calming funds, ranking will be based on total points and project cost. Traffic calming projects must score a minimum of 30 points in order to be considered for implementation.

Table 1
Traffic Studies

Study TypePurposeMethod
Speed Counts Determine speed Mechanical Hose counts
Volume Counts Determine volume Mechanical Hose counts
Screenline Counts Determine total vehicles traveling into and out of neighborhood Mechanical Hose counts
Crash Reports Determine nature of reported crashes Review crash reports
Origin-Destination Survey Distinguish local from non-local traffic Two screenlines or manual recording
Pedestrian Crossing Survey Determine frequency and location of pedestrian crossing Manual recording of time between vehicle arrivals during given time period
Intersection Turning Movement Counts Determine source and destination of drivers using streets Manual counts
Vehicle Classification Survey Determine percentage of vehicles that are cars, trucks, buses, etc. Mechanical Hose counts
Parking Survey Determine how streets and parking lots are utilized during day Manual survey of parking inventory and utilization
Street Classification Determine street classification From Comprehensive Plan
Posted Speed Limits Use as basis Taken from posted speed
Physical Street Data Determine lane width, etc. Field measurements
Community Facilities Inventory    
Emergency and Evacuation Routes    
Truck Routes    


Speed and volume usually precipitate the request for traffic calming within a neighborhood.  Traffic crashes are added as extra points because a crash problem usually coincides with higher volumes and speed.

Residential density also affects general traffic conditions.  For example, higher densities tend to generate more pedestrian and vehicle turn movements.  In addition, projects on higher density streets tend to benefit more people than projects on lower density streets.

The other criteria, sidewalks, school crossings, and pedestrian generators, are important considerations because they relate to pedestrian safety.

Table 2
Project Point Assignment
Local Streets

Criteria  Points  Basis 
Speed (85th percentile) 0 to 40 10 pts for every 5 mph over posted speed limit
Volume 0 to 40 ADT divided by 100
     
     
     
     
     

Criteria Points Basis
Speed (85th percentile) 0 to 40 10 pts for every 5 mph over posted speed limit
Volume 0 to 40 ADT divided by 100
No Sidewalks 0 to 10 5 pts if no continuous sidewalk, 5 pts if signs of heavy pedestrian traffic w/out sidewalks
Traffic Crashes 0 or 5 1 pt for each crash/year at one location
School Crossing 0 or 5 5 pts if children must cross street to get to school
Total Points Possible 100  

Table 3
Project Point Assignment
Collector Streets

CriteriaPointsBasis  
Speed (85thpercentile) 0 to 30 5 pts for every 5 mph over posted speed limit    
Volume 0 to 25 5 pts for every 1,000 ADT on any one street    
Traffic Crashes 0 to 15 1 pt for every 2 crash/year at one location    
No Sidewalks 0 or 10 5 pts if no continuous sidewalk, 5 pts if signs of heavy pedestrian traffic w/out sidewalks    
Residential Density 0 to 5 1 pt for every 100 dwelling units/mile    
School Crossing 0 or 5 5 pts if children must cross street to get to school    
Pedestrian Generators 0 or 5 5 pts if pedestrian generator    
Transit Availability 0 or 5 5 pts if not on transit route    
Total Points Possible 100      

Design Criteria

As stated earlier traffic calming measures are self-enforcing physical features in the design of the roadway which effectively change the design speed.  The neighborhood will be instrumental in the development of traffic calming plans to tailor the design to area characteristics.  The design of traffic calming measures must, however, be undertaken using due diligence and responsible engineering judgment of the responsible designer.

The following criteria shall be used as design guidelines for those projects meeting the criteria set in Section III above.

  • The posted speed may not be more than thirty (30) miles per hour.
  • Limited to streets having only one lane of through traffic in each direction.
  • Streets must not be primary emergency or evacuation routes.
  • At the discretion of the City Engineer, certain traffic calming measures may not be used if they would create an unsafe condition for motorists driving at normal speeds under average driving conditions.
  • Streets must not be through truck routes unless an acceptable alternative route is identified and approved.
  • If a calming plan could divert more than five percent (5%) of the traffic to another local or Collector Street, such street shall also be considered for traffic calming.

Project Financing

The ultimate factor regarding the implementation of traffic calming projects will be the availability of funding.  Funding sources include the annual capital improvement program, special assessments, or federal or local grants.

Project Selection

Projects scoring a minimum of thirty (30) points will be ranked and be presented to the City Commission for approval.  Projects approved by the City Commission will still need to be compete for funding as part of the regular Capital Improvement Program (CIP) annual process.  Several factors will be considered when deciding whether to fund a traffic calming project.  The factors include size and complexity of calming project, timing with other infrastructure improvements, and availability of funds.

Project Implementation

Only after a calming project is funded will the design phases begin.  The following is a guideline to use when trying to determine when construction on a calming project will begin:

1 Project Petition-To-Study Ongoing
2 Preliminary Review Within 3 months of request
3 Priority Ranking Within 3 months of preliminary review
4 Funding? Yes-continue,  No-wait until funding available
5 Survey, Design, Review Meetings 6-9 months
6 Construction 3-6 months                            

Project Evaluation

Approximately six (6) months after the traffic calming project is completed additional data will be collected and compared to the "before" data.  The purpose of comparing "after" data to "before" data is to evaluate the effects of the project.  If any unacceptable impacts are identified, corrective measures may be taken.

Removal of Traffic Calming Measures

Traffic calming measures can be removed after the evaluation period for any of the following reasons:

  • Emergency response is significantly impacted.
  • The identified traffic problem that the calming measures were to eliminate is transferred to another adjacent street or neighborhood.
  • At least 75% of the property owners within the defined neighborhood sign a petition to remove the calming measures. (This option will result in complete removal of all measures.  All residents within the defined neighborhood will be assessed for the removal of the calming measures.)

Traffic Calming Measures

Roundabouts
A raised circular structure constructed in an intersection designed to deflect the flow of traffic entering the intersection in a counter-clock-wise direction around the circle. The objectives of roundabouts are to slow traffic and reduce the number and severity of crashes. Roundabouts are designed to accommodate all sizes of vehicles. These features address vehicle speeds and may discourage cut-through traffic.

Semi-Diverter
Islands installed on the ingress side of the street in which entry is being prohibited. Vehicles are still allowed to exit from this street but entrance is prohibited. This feature discourages (actually prohibits) cut-through traffic.

Mid-Block Islands
Islands constructed mid-block in the center of the roadway separating driving lanes and may reduce lane widths. The objectives of mid- block islands are to slow traffic and reduce the number and severity of crashes. These features address vehicle speeds and may discourage cut-through traffic.

Splitter Islands
These are treatments that may provide landscaping and physical channelization to lanes at the entrances to the neighborhood. The objectives of splitter islands are to slow traffic and discourage cut-through traffic.

Roadway Narrowing
These treatments reduce the width of pavement while maintaining two- way traffic. Landscaping planted in conjunction with the narrowing may further enhance the feature and impact driver behavior by reinforcing the impression that the pavement area is limited. The objectives of roadway narrowing are to slow traffic and reduce the number and severity of crashes. These features address vehicle speeds and may discourage cut-through traffic.

Forced Turn Islands
The installation of raised islands at the approach to an intersection prohibits vehicles from making certain movements. The objectives are to slow traffic, reduce the number and severity of crashes, and prohibit certain turning movements.

Chicanes
This feature changes the alignment of the roadway so that the street is not straight. This eliminates driver tendencies to accelerate on a straight street and may add beautification opportunities without significantly impacting emergency services. Two-way traffic and full access for larger vehicles and emergency services is maintained. The objective is to slow traffic. These features address vehicle speeds and may discourage cut-through traffic.

Neighborhood Signs
May be included at the entrance(s) to the neighborhood to advise motorists that the area is "traffic calmed". This may eliminate or reduce the use of other warning signs within the neighborhood, at the discretion of the City Engineer. These signs discourage cut-through traffic.

Speed Humps
Street pavement can be raised and the surface treated; the physical change in the roadway may slow vehicles. Speed humps shall not be used on roadways designated as primary access routes. The objective is to slow traffic and reduce the number and severity of crashes. These features address vehicle speeds and may discourage cut-through traffic.

Speed Tables
A type of speed hump with a flat top that may also be used as a raised pedestrian crossing area. They are generally three to four inches high, have a six-foot sloped approach, with a ten-foot top, and a six-foot sloped departure profile. The objective is to slow traffic and reduce the number and severity of crashes. These features address vehicle speeds, increase visibility for pedestrians and may discourage cut-through traffic.

Raised Intersections
A raised intersection involves the construction of the entire intersection 3" to 4" above the approaching streets. The intersection is typically constructed of a different material type or the approaches are of different material to indicate a change at the intersection. The objectives are to slow traffic and reduce the number and severity of crashes. Raised intersections are designed to accommodate all sizes of vehicles. These features address vehicle speeds and may discourage cut-through traffic.



Contact:
Xavier Falconi
Principal Transportation Professional
falconix@mydelraybeach.com
Phone: (561) 243-7000
Extension: 4113
Fax: (561) 243-7060

 

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