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Chapter 4
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Design Criteria
4.13 Bicycle Facilities

Bicycles are legally considered vehicles and therefore legally allowed to operate on any public roadway except where specifically restricted. There are many features and design elements associated with traffic and signal operations that can greatly enhance the attractiveness and safety of bicycling in the roadway.

4.13.1 Links to Standard Plans and Specifications


Standard Plan #265: Vaned Grate
Standard Plan #722: Bicyclist and Pedestrian Symbols
Standard Plan #724: Bicycle Symbol
Standard Plan #724: Bicycle Detector Pavement Marking

4.13.2 Design Criteria

Per RCW 35.75.060 and 36.82.145, all bicycle facilities must comply with Chapters 1515 and 1520 of the WSDOT Design Manual which is consistent with the 1999 AASHTO Guide for the Development of Bicycle Facilities.

Drain grates: Must be designed such that narrow tires cannot get caught. When new drain grates are installed or existing drain grates replaced, they must conform to the vaned grate design specified in Standard Plan #265. The drain grate design specified in Standard Plan #264 should not be used in any location where bicycles may be present.

Deck grating: Can be extremely slippery, particularly in wet conditions. Bicycle tires, with their small contact area, are extremely vulnerable to loss of traction. If deck grating must be installed, it must be treated to increase traction and the seam width between the decking and the adjacent pavement should be no wider than 3/8 inch.

Signal detection sensitivity: Loop detector systems, and any other detection system employed such as camera-based motion detection systems, must be sensitive enough to recognize bicycles or bicyclists. These systems should also accommodate the trend in bicycle technology which is resulting in bicycles being manufactured with decreasing amounts of metal.

Pavement markings for loop detector systems: As required by State law, RCW 47.36.025, with new construction or upgrade of detection equipment; bicycle loop detector systems should be accompanied by pavement markings that indicate the location where a bicycle should be located to maximize its disruption of the inductance field. Specifications for this pavement marking are illustrated in Standard Plan 725.

Bicycle Parking
On-street bicycle racks: Racks must have the following characteristics:

  • are intuitive to use correctly;
  • have a no-maintenance finish that won’t chip, peel, or rust. Galvanized steel finishes are preferred;
  • support the frame of the bicycle;
  • allow a u-style lock to secure one of the wheels and the frame to the rack;
  • allow removal of the front wheel and locking it with the rear wheel and frame to the rack;
  • have a minimum height of 2.5 feet so it is not a tripping hazard;
  • are installed as close to, without being directly in front of, the main entrance(s) of a building or site; and
  • have adequate clearance from driveways, curb ramps, transit loading areas and immediately adjacent to shelters, and utility poles.

The SDOT bicycle rack program website has sample racks and more information.  SDOT will assume ownership and maintenance of bicycle racks once they are installed.

Private, off-street bicycle parking requirements are specified in the Land Use Code.

SMC 23.49.019 Downtown Parking Quantity Requirements
SMC 23.54.015 Required Parking
SMC 23.54.016 Major Institutions Parking and transportation
SMC 23.54.020 Parking Quantity Exceptions

Bicycle Master Plan:  The City of Seattle’s Bicycle Master Plan was published in 2007.  The Bicycle Master Plan established a recommended bicycle facility network and defined the type of bicycle facilities to be placed on the identified streets. 

The following are design criteria for some of the more common bicycle facilities identified in the Bicycle Master Plan.  Refer to the Bicycle Master Plan for a full description of all the facility types.  The following criteria should be used in conjunction with the current MUTCD and Chapter 1020 of the WSDOT Design Manual which is consistent with the 1999 AASHTO Guide for the Development of Bicycle Facilities. 

Bicycle Lanes: The minimum width for a bicycle lane is five feet adjacent to a parking lane and 4 feet adjacent to the curb. Bicycle lanes should include a bicycle pavement marking with an arrow to indicate that bicyclists should ride in the same direction as adjacent motor vehicle traffic. When adjacent to parking, secondary striping is installed to delineate the parking lane from the bike lane. Where the edge line separating the bike lane from a motor vehicle lane is 13 feet from the curb or edge of roadway, the secondary striping should be installed no more than 8 feet from the curb or edge of roadway. Where the edge line separating the bike lane from a motor vehicle lane is less than 13 feet from the curb or edge of roadway, the secondary striping should be installed 7 feet from the curb or edge of roadway.

Shared lane markings: Shared lane pavement markings (or “sharrows”) are bicycle symbols that are placed in the roadway lane indicating that motorists should expect to see and share the lane with bicycles. Unlike bicycle lanes, they do not designate a particular part of the roadway for the use of bicyclists.  The design location for sharrows should conform to the MUTCD.  In addition, a near side sharrow will also be placed at arterial intersections with traffic control and at intersections where there is a far side bus stop and the far side sharrow is placed at the end of the bus stop. At locations where it is desirable to encourage motorist to pass the bicyclist by changing lanes or to wait until they reach a location where the lane widens, moving the marking towards the center of the travel lane should be considered.

Climbing Lanes: Climbing lanes are a hybrid bicycle facility that includes a five foot bicycle lane on one side of the roadway (typically in the uphill direction) and a shared lane marking on the other side of the roadway.

Bicycle Facility Design:  The following are criteria to follow when designing bicycle facilities or street improvements that may impact bicyclists:

  • Paint or traditional thermoplastic are not satisfactory materials for bicycle lane symbols. Pavement markings should have a thickness no greater than 75 mil and must have retro-reflective and skid-resistant properties. Preformed type B thermoplastic legends should be used for bicycle facilities.
  • Vertical obstructions within the path of bicycle travel are not recommended, but in some cases may exist. The pavement marking described in Figure 4-20: Obstruction Warning Pavement Marking provides a visual indication to bicyclists plan for an upcoming obstruction.
  • Typical small-scale berms should have an average approach slope of 2%. For example, the approach to a 1.5 inches high berm should be 6 feet long. Berms with shorter approaches increase the likelihood that a bicyclist will lose control of their bicycle, especially those with high pressure tires or without any suspension.
  • Concrete panels should be aligned such that seems should be located outside of the zone that bicyclists commonly travel. For example, this zone is typically 10-12 feet from the curb when on-street parking exists.
  • The seam width between concrete panels should be no wider than .25 inch; vertical faulting must be maintained at a maximum of .25 inches.
  • The minimum setback of a trail from railroad tracks/train should be 10 feet.


4.13.3 Design Considerations

Certain physical characteristics of bicycles require that our transportation system be built and maintained in a manner so bicycles can be safely operated. These characteristics, which are more common in road-style bikes than off-road style bikes, include:

  • narrow tires, down to 20mm in width;
  • small contact patch with the roadway surface;
  • small mass of metal (steel, aluminum, or titanium) compared to motor vehicles;
  • high tire pressure, typically 100+ psi; and
  • lack of suspension.

These physical characteristics should be considered when designing bicycle facilities.

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continue to section 4.14 »   
Latest Online Manual
Detailed Table of Contents
Chapter 4
Design Criteria
4.1 Introduction
4.2 Street Classifications and Street Types
4.3 Design Criteria General Notes
4.4 Grading
4.5 Design Cross Section
4.6 Roadway Width
4.7

Roadway Pavement

4.8 Intersections
4.9 Driveways
4.10 Curbs
4.11 Sidewalks
4.12 Crosswalks
4.13 Bicycle Facilities
4.14 Street Trees and Landscape Architectural Standards
4.15 Introduction to Utilities Design Criteria
4.16 Street Lighting
4.17 Street Drainage, Storm Drains and Sewers
4.18 Water Mains
4.19 Fire Protection
4.20 Seattle City Light
4.21 Clearances
4.22 Structures in the Right-of-Way
4.23 Culdesacs and Turnarounds
4.24 Traffic Operations
4.25 Transit Zones
4.26 Street Furniture, Public Art and Unique Objects in the Public Right-of-Way
4.27 Access Easements
4.28 Contact Information
   
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