Neighborhood Traffic Management Program (NTMP) for neighborhood streets represents the commitment of the City of Sammamish to the safety and livability of residential neighborhoods. It is a joint effort between residents, the Public Works Department, and Sammamish city Police to reduce the impact of traffic on neighborhoods. The NTMP provides a process for identifying and addressing traffic concerns. Under the program, Public Works staff and city police work with residents to evaluate the type and severity of traffic issues. Through active participation by citizens, we can identify the problem, plan the approach, implement solutions, and evaluate their effectiveness.
The city of Sammamish places a high value on neighborhood livability. Although livability has no precise definition, it can be thought of as encompassing the following characteristics:
Traffic management plays a vital role in the promotion these characteristics.
The overall goals of the NTMP are derived from existing city policy. They are:
The program is a two-phase, two-year process. Phase I focuses on passive, less-restrictive measures. This includes educational programs, enforcement, pavement markings, and signing. Should “Phase I” actions prove ineffective, more restrictive “Phase II” methods and physical devices may be considered, based on certain threshold criteria.
Neighborhood Traffic Management Program: Phase I
Education, Public Awareness, Enforcement, and Passive Measures
The first step is to identify the traffic concerns in your neighborhood and inform the city’s Public Works Department. You can do this by using the online Citizen Request For Action, also available as a paper form in the kiosk at City Hall. Alternately, you may submit a formal letter addressed to:
Sammamish Public Works Department Attn: Steven Chen, Traffic Engineer 801 228th Ave SE Sammamish, WA 98075
Steven Chen is the engineer in charge of this program; if you have questions, you may contact him at 425-295-0564. However, until the formal request is submitted to the city in writing, your neighborhood will not be placed on the list to be scheduled for evaluation.
Once we receive your request, a site visit will be conducted to review current traffic control measures including pavement markings, signs, sight distance, and road conditions. Next we will collect pertinent data (historical traffic data, volume and speed counts, etc.) for further evaluation.
From this information PW staff and city Police will compose a Neighborhood Traffic Plan for the location and inform you of our findings and recommendations for Phase I solutions. This review takes approximately 6 to 8 weeks from the day we receive your request.
Possible Phase I solutions may include one or more of the following:
Once the Proposed Improvement Plan has been formulated, PW staff and city Police will work with concerned citizens to initiate recommended solutions. Approximate time line: 12 to 16 weeks.
Neighborhood Traffic Management Program: Phase II
Traffic Calming Projects
Phase II of the program begins approximately 32 weeks from the implementation of Phase I. The city again collects data and compares it to Phase I information. Should the traffic concerns still exist and there is sufficient data to support this, then the location will be reviewed for the construction of physical devices.
Possible Phase II solutions may include, but are not limited to, the following physical devices:
Step 1: Project Consideration and Preliminary Review
PW staff reviews and gathers additional data if necessary. The potential project is rated using “Point Assignment for NTMP Projects” (Attachment A). The numerical score helps determine placement on a priority list. Approximate time line is 4 to 8 weeks.
Step 2: Plan Development
A public meeting is held to inform residents of pending project and to gather further information. PW staff is responsible for public notification. Approximate time line is 4 to 6 weeks.
Step 3: Ballot for Design and Construction
The project plan is modified if necessary and placed on a funding priority list. The requestor is then responsible to circulate a ballot for permanent device construction. A 60% signature rate is needed to proceed. Final design and construction is contingent of funding. Approximate time line is 16 to 26 weeks (Target for construction is 100 weeks from original Phase I request date).
Step 4: Reporting of Design and Construction
PW staff generates report of final design and construction schedule and distributes it to study area, preferably through an active HOA or neighborhood point of contact. Approximate time line is 4 to 8 weeks.
Step 5: Landscaping
Initial installation costs associated with landscaping will be covered by the city’s construction project. If landscaping of NTMP devices is feasible and desired by the neighborhood maintenance will be negotiated with the neighborhood and/or adjacent property owners. If the neighborhood fails to fulfill the assigned responsibility and the landscaping obstructs the view of traffic or becomes unsightly the city reserves the authority to remove the landscaping.
Step 6: Follow Up Evaluation
Within three to five years after construction of an NTMP project, the Public Works Department will conduct a follow-up evaluation to determine if the project’s goals and objectives continue to be met.
Point Assignment for NTMP Projects
The following information is used to develop a numerical score for each NTMP project request. Scores are used to rank requests on a citywide basis. A high-ranking, available budget, and other factors are used to determine which projects will precede to the petition-to-study stage.
Traffic Management Devices
This section provides a brief description of some commonly used traffic management devices.
Traffic circles are raised islands placed in an intersection. The primary purpose of a traffic circle is to slow high-speed traffic. Traffic circles are most effective when constructed in a series on a local service street.
Chokers or curb extensions narrow the street by widening the sidewalk or the landscaped parking strip. These devices are employed to make pedestrian crossings easier and to narrow the roadway.
Chicanes are similar to chokers or curb extensions by narrowing the existing street with an alternating pattern. These devices require the driver to shift his line of travel from one side of the street to the other. Installed correctly, chicanes may make the street appear to have a restricted or limited access.
Semi-diverters limit access to a street from one direction by blocking half the street allowing only bicycle, pedestrian, and transit access. They may also be constructed to limit certain movements (left or right turns and through movements) at an intersection.
Diagonal diverters place a barrier diagonally across an intersection, disconnecting the legs of the intersection.
Intersection channelizations are designed to limit certain movements, narrow the intersection, or otherwise direct traffic. They are unique to each intersection and can take a variety of forms. An example is a median island that restricts through movement.
Narrow Points reduce the roadway width to one 12-foot travel lane. The one lane requires drivers to take turns driving through the device. Narrow Points make the street more visually restrictive.
Speed Bumps. Two types of speed bumps are approved for use on city streets. Local access 14-foot bump and the Neighborhood collector 22-foot bump. Both bumps are designed to slow traffic to 20 mph and 30 mph respectively.
Traffic Control Devices
Stop Signs are used to assign right-of-way at an intersection. They are installed at intersections where an accident problem is identified or where clear right-of-way may be in doubt.
Stop signs are generally not installed to divert traffic or reduce speeding. Stop signs or multi-way stop intersections can be used in conjunction other traffic management devices.
Modern Roundabouts are traffic control devices approved by the city for controlling traffic and reducing accidents. They can be utilized in place of traffic signals or stop signs or in conjunction with same. Three principle design features distinguishing the Modern Roundabout from Traffic Circles are:
All of the streets in Sammamish are classified by the city's arterial streets classifications. Those classifications designate a hierarchy of streets to serve different kinds of trips, and different volumes of traffic, traveling at different speeds. They are intended to guide future development of Sammamish's transportation system. They do not mandate any specific projects or any changes in traffic movement or transit service. The arterial streets classifications and policies are not a strict guideline for current operation of Sammamish's street system; thus, some streets may not now be operating in accordance with their classification.
Neighborhood streets make up the, great majority of Sammamish's street neighborhood collector streets. These streets serve local circulation needs for autos, bicycles, and pedestrians and provide access to land uses located on the street. Local access or neighborhood streets should not carry significant volumes of through traffic. Most reported neighborhood traffic problems are concerned with the interactions of autos and residential livability on neighborhood streets.
Neighborhood collectors are intended to be the links between the local access or neighborhood streets, collectors, and arterial streets. Shorter trips and access to commercial uses should also be emphasized in the design of neighborhood collectors.
Major collector streets are similar to neighborhood collectors, except they serve larger geographical areas and/or more concentrated development.
Arterial streets are designed to serve trip movements between different sections of the city and to allow access to abutting properties without disrupting traffic flow.
may be the most often noted and discussed of neighborhood traffic problems. Local access streets, where not posted, have speed limits of 25 miles per hour. As needed/requested, the Public Works Department will conduct a speed study to determine the appropriate speed limit on a given street. Factors considered by the Public Works Department include land use, accident history, type of roadway, and existing speeds driven by motorists.
is another of the most commonly reported local traffic problems. Volume refers to the number of vehicles that cross a given section of roadway during a specified time period. In Sammamish, volumes are normally measured on weekdays for at least 24 hours.
Accident history information
Is used to determine safety problems at a given location. Accidents, particularly at low-volume residential intersections, are often random. An average of less than one reported accident per year usually does not indicate a safety hazard. An average of one or more reported accidents per year can be significant, particularly if there is a pattern of several similar accidents having occurred. When a pattern is apparent, the problem can be identified and appropriate solutions developed.