1. Community Engagement

  2. Design

  3. Complete

Project Overview

The city's Design and Construction Standards (DCS) and Boulder Revised Code (BRC) include standards governing how transportation infrastructure must be designed and constructed in the public right-of-way.

How are these standards used?

  • Private entities that build or operate public utility and transportation infrastructure in the public right-of-way in Boulder must follow these standards.
  • Residents and other property owners would also have to follow the new sight triangle standards when doing certain site improvements on their property, such as replacing fencing or landscaping or when considering a new structure adjacent to the public right-of-way or public access easement.
  • City staff also follow these standards for capital improvements projects.

The city is currently updating these standards to better align with current best practices and the city’s vision for a multimodal, connected transportation system, according to the city's Transportation Master Plan and Low-Stress Walk and Bike Network Plan.

Spring 2022 Community Engagement

The public feedback window has closed. Thanks to all who provided input!

Topic Proposed Change
Vehicle Lane Widths

Update lane widths table with new, narrower preferred widths to align with current best practice for constructing streets that serve people walking and bicycling. See Table 2.5

Anticipated benefit: Narrower lane widths typically yield slower vehicle speeds

Bike Lane Widths

Add lane widths for all expected types of bike lanes including conventional, buffered, separated, and parking-protected. See Table 2.5

Anticipated benefit: Providing standard widths for bicycle lanes will lead to more consistent projects that prioritize bicyclist safety and comfort

Separated Bike Lanes

Provide additional technical information about operating speed of bicyclists and the effect on design features

Anticipated benefit: Providing more nuanced information about separated bike lane design will lead to more consistent design of separated bike lanes that are comfortable for bicyclists of all ages and abilities

Corner Radii

Update guidance and standards to help designers achieve smaller effective radii of curbs, especially through the use of curb extensions. See 2.07 (D)(5)(d) Figures 1 and 2

Anticipated benefit: Slower turning speeds and increased comfort for people walking and biking

Road Width Tapers

Add information about bike lane tapers in addition to existing motor vehicle lane tapers

Anticipated benefit: Eliminating bike lane designs with abrupt tapers (changes in direction) that can cause rider discomfort

Left-Turn Lanes

Clarify goal to use a single left-turn lane first, then dual left turns if necessary. Add statement that triple left-turn lanes are only allowed with Director approval.

Anticipated benefit: Reducing the number of left-turn lanes at intersections shortens crossing distances for pedestrians and bicyclists

Topic Proposed Change
Separated Bike Lanes at Driveways

Add new figures

Anticipated benefit: Separated bike lanes typically cross driveways and alleys. Standardizing this element of design can improve visibility of bicyclists and improve yielding compliance.

Separated Bike Lanes at Intersections

Add new figures

Anticipated benefit: The most complex aspect of separated bike lanes is at intersections. Providing examples of how to maintain safety and good sightlines through the intersection will lead to consistent design of future projects.

Topic Proposed Change
Neighborhood Traffic Circles

Add new figures

Anticipated benefit: Neighborhood traffic circles are a great traffic calming technique for local streets. Standardizing their design with typical dimensions will help provide consistent design of future projects.

Raised Crossings

Add new figure

Anticipated benefit: Standardizing raised crossing design will help provide consistent traffic calming and yielding compliance benefits.

Topic Proposed Change
Bike Ramp Drawing

Add new drawing

Anticipated benefit: Provide a detailed standard for bike ramps that connect on-street bike lanes to sidewalk-level multi-use paths, providing a more comfortable and safe transition for bicyclists of all ages and abilities

Curb Extension Drawing

Add new drawing

Anticipated benefit: Curb extensions help slow turning vehicles and reduce pedestrian and bicyclist crossing distances. A new standard drawing will lead to consistent design of future projects.

Floating Bus Stop Drawing

Add new drawing

Anticipated benefit: Many streets proposed for separated bike lanes also have bus routes. A new standard drawing will lead to consistent design of future projects.

Raised Crossing Drawing

Add new drawing

Anticipated benefit: Raised crossings slow vehicles and make pedestrians more visible. A new standard drawing will lead to consistent design of future projects.

Multi-Use Path Section Detail Drawing

Update drawing

Anticipated benefit: Noted maximum vertical clearance of 8' to match Ch. 2 text.

Crosspan and Radii Curb Return Accesses Drawing

Update drawing

Anticipated benefit: Changed minimum intersection radius from 10' to 5' to match Ch. 2 figure.

Median Paved Curb Skirt Drawing

Update drawing

Anticipated benefit: Added 4' min width for a landscaped median; added a note for 4" min depth of topsoil required to match Ch. 3 text

Median Separated Bike Lane Drawing

Update drawing

Anticipated benefit: Changed minimum separated bike lane width to 6.5' min, 7' preferred to match Ch. 2 text.

Bicycle Path Cross-Section Drawing

Update drawing

Anticipated benefit: Changed vertical clearance to 8' to match Ch. 2 text; changed max foreslope/backslope from 4:1 to 3:1; changed shoulders to earth pattern, removed on-street bike lane typical section.

Non-Residential Street Cross-Section Example Drawings

Update two drawings: Arterials and Collectors

Anticipated benefit: Added note for designer to verify if route is on Boulder's Low Stress Walk and Bike Network, which has implications for recommended facility type between on-street bike lanes and separated bike lanes.

Streetscape Tree Spacing and Location Drawing

Update standard drawing to include more details about tree spacing in different streetscape contexts

Anticipated benefit: Will lead to consistency in planting locations

Streetscape Tree Spacing and Location Offset Drawing

Add a secondary standard drawing that shows the offset distances for various amenities and utilities

Anticipated benefit: Makes the offset requirements more clear visually, aiding designers in developing great landscape plans.

Tree Grate for Sidewalk Planting Drawing

Update drawing to include tree guard and revised tree grate detail. Modify location of amended soil. Add information on soil volume.

Anticipated benefit: Provide a standard for tree plantings in urban sidewalk areas that will lead to a healthier tree thereby increasing tree canopy.

Topic Proposed Change
Tree Species List

Remove tree species references in standards text and insert reference to regularly updated tree list

Anticipated benefit: Allows Boulder Forestry staff to maintain an Approved Tree List that can be updated on a regular basis to provide the best trees for the local context at any given time.

Limitations on Individual Tree Species

Update Tree Species table with more modern standards. Updated table

Anticipated benefit: Promote tree diversity in the City of Boulder and reduce instances of monoculture plantings of trees.

Tree Soil Volumes

Increase minimum soil volumes

Anticipated benefit: Promote healthier trees

Streetscape Tree Spacing and Location

Update standard drawing to include more details about tree spacing in different streetscape contexts. Updated drawing

Anticipated benefit: Will lead to consistency in planting locations

Streetscape Tree Spacing and Location

Add a secondary standard drawing that shows the offset distances for various amenities and utilities. New drawing

Anticipated benefit: Makes the offset requirements more clear visually, aiding designers in developing great landscape plans

Tree Grate for Sidewalk Planting Drawing

Updated drawing to include tree guard and revised tree grate detail. Modify location of amended soil. Add information on soil volume.

Anticipated benefit: Provide a standard for tree plantings in urban sidewalk areas that will lead to a healthier tree thereby increasing tree canopy.

Topic Proposed Change
Soil Requirements

Updated soil definitions to match modern standards

Anticipated benefit: Improvement in quality of soil and clarity on soil amendments.

Topic Proposed Change
15’ x 15’ Sight Triangle

This is not a new sight triangle. The proposed change will change the location of where the sides of the sight triangle are measured when the public street has a sidewalk. Currently the sight triangle is measured along the right-of-way line of the public street and either the right-of-way line of the public alley or the edge of the private driveway and whose third side is a line connecting the two sides. Updated figure

Anticipated benefit: This change will provide staff with physical features to measure the sides of the sight triangle when responding to sight triangle complaints.

Multi-use path intersecting either an Alley or Driveway

This is a new 15’ x 96’ sight triangle that will be added to the sight triangle section of the Boulder Revised Code. The sides of the new multi-use path sight triangle would be 15’ x 96’ with the third side of the sight triangle being the line that connects the two sides. New figure

Anticipated benefit: The 15’ x 15’ sight triangle is currently used where a multi-use path (path) intersects with either a driveway or alley. The new sight triangle increases the sight triangle area between the path and either a driveway or alley.

Virtual Office Hours

City staff held office hours in April to answer questions related to the Transportation Design Standards Update. Thanks to all who attended!

Background

The updates to the transportation design standards are part of a larger, multi-year effort to update the city's Design and Construction Standards (DCS). A first round of community feedback on the draft transportation design standards was collected in fall 2021.

The proposed changes are designed to respond to community feedback and better align with current best practices and the city’s vision for a multimodal, connected transportation system, as reflected in Boulder’s Transportation Master Plan, Low-Stress Walk and Bike Network Plan and Forestry Strategic Plan.

The current DCS was adopted in 1998 and updated in 2000 to prescribe minimum standards to be used in the design and construction of public infrastructure located in public right-of-way and easements in the city of Boulder, as well as private transportation improvements that connect or impact public infrastructure. The DCS is enacted through the BRC and changes are adopted by City Council with recommendations from appropriate boards, such as TAB and Planning Board.