Category: Street Design Standards

update on SacCity ADA ramps

Dan AllisonLeave a comment

Note: I discovered that I have often used ‘detectible’, but should have been using ‘dectectable’ for detectable warning strips.

This is an update to the update on work being done on corner ADA ramps in the Sacramento central city, apparently as part of the Central City Mobility Project.

So far as I have seen, curb extensions are not part of this project.

There are now a number of locations where the concrete ramp is being cut so that the detectable warning strip can be installed, but the curbs are not being touched. See below for an example.

Q-St & 16th-St, SW corner, ADA ramp construction
Q-St & 16th-St, SW corner, ADA ramp construction

One of the corners I have been monitoring, 21st St and O St northeast corner, is complete, but with temporary patches that make the ramps useable, though ironically still blocked by folding barricades and caution tape, which absolutely does not meet ADA guidelines for contruction signing and safety. This seems to be the pattern with the city, trying to make things better, but not paying attenteion to the details. I don’t know when the asphalt will be restored and the corner opened. Maybe the contractor is waiting until all the corners are ready before patching, though that would be stupid.

21st-St & O-St, NE corner, completed corner with ADA ramps
21st-St & O-St, NE corner, completed corner with ADA ramps

I am still not able to make sense of the asphalt cuts that are being done on the corners where the curb will be or has been modified. I’m guess that there was a standard cut design, implemented everywhere, no matter what the actual project.

Walking around the central city, it appear that most of the corners which did not have ADA-compliant ramps will have them when the project is done, but some may not. I don’t know what the criteria is for which corners are being done, and which are being done at a higher level of replacing the curbs and widening the ramps. Many of the existing ramps are narrow, with edging curbs, which was apparently the design at the time they were placed, but the new corners are a different design, with a sloping area between the two ramps, similar to the diagram below, from the 2020 Department of Utilities Standard Specifications: Transportation drawings, not from the 2009 Department of Public Works Street Design Standards, which contain no ADA diagrams. I think the detectable warning strip width is at least 60 inches on the new installations, which is an improvement. The 48 inch width does not allow two people to stand on the strip. Corners with new curb extensions seem to have 72 inch strips.

SacCity T-76 Curb Ramp Dual Combination Planter diagram
SacCity_T-76_CurbRampDualCombinationPlanter

SacCity street classification

Dan Allison4 Comments

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so.

After much thought, and feedback from other transportation advocates, I am finally ready to propose street classifications for the revision of the street design standards. I have written about street classification before: how to classify streets?; NACTO yield street; NACTO neighborhood main street; NACTO downtown streets.

I am offering only three street classifications. I know most classification systems use more, but I’m for simplicity. A key part of this classification scheme is that streets with more than two lanes per direction are NOT streets, and should be called roads instead. Of course they are stroads, but the city is unlikely to use that term. A road is for traveling, and therefore should have few to no driveways and few to no turning movements. Every driveway and ever turning movement is an invitation to conflict and crashes. The arterial roadways in the city fit into the stroad category. We don’t need them, and we should never construct another.

Street classification (see below for diagrams):

  • local or yield: narrow lane (unmarked), parking, up to 20 mph; for local travel
  • neighborhood: two lanes, regular bike lanes, up to 30 mph; for local and through travel
  • corridor: two to four lanes, bus lanes, separated bikeways, up to 40 mph; for local and through travel
  • traditional functional classification system (arterial, collector, local) will not be used; classification into residential, commercial, etc will not be used since all areas may be mixed use
  • new or reconstructed streets will not be designed for more than two lanes per direction

Policies

  • All one-way multiple lane streets should be considered for conversion to two-way streets
  • One-way single lane streets will be considered for narrow right-of-ways widths or where right-of-way is needed for other purposes
  • Streets which are repaved and re-striped (reallocated) but not reconstructed will include striping that increases safety and reduces speeds
  • Reconstructed streets will be designed for the level of VMT (vehicle miles traveled) or  ADT (average daily traffic) that is desired for safety, livability and economic vitality; the design or posted speed limit prior to reconstruction will not control in any way the new design
  • Design for reconstructed streets will consider the reduction or consolidation of driveways, and particularly of driveways that are too close to intersections
  • Driveway width for single family residences will be no more than 10 foot width; driveways for multi-family and commercial areas will be the minimum required by fire agency
  • Center turn lanes will be used only where frequent turning movements into or out of driveways are expected and accepted; they will not be used to fill excess roadway width
  • Speed humps or tables on a street generally indicates a failure to design for the desired speed, and will not be used on new or reconstructed streets, and only as a temporary solution on other streets
  • When streets are re-striped after repaving, but are not reconstructed, the excess lane width will be devoted to other uses or marked off as invalid travel areas
  • Designs will not include dedicated right hand turn lanes, and will not include multiple left hand turn lanes
  • Rough pavement surfaces such as brick, cobblestone, or stamped concrete will be considered whenever reduced speeds are desired; however, crosswalks and bike facilities will be smooth
  • Rolled curbs will not be used on new or reconstructed streets  
  • Streets which are repaved will implement, to the degree possible, the same design as reconstructed streets via right-of-way reallocation and striping

Design diagrams:

  • NACTO-like diagrams which show the overall design of each street type
  • One-lane, one-way streets
  • Woonerfs (shared streets) without curbs and with design elements to ensure speeds of 10 mph or less
  • Bioswales for management of storm water

The remaining post in this series will be about intersection of neighborhood streets, and corridor streets. Stay tuned!

local or yield street diagram, 58 foot right-of-way width, center lane is bi-directional and narrow, from StreetMix
local or yield street diagram, 58 foot right-of-way width, center lane is bi-directional and narrow, from StreetMix
neighborhood street diagram, 90 foot right-of-way width, from StreetMix
neighborhood street diagram, 90 foot right-of-way width, from StreetMix
corridor street diagram, 90 foot right-of-way width, from StreetMix
corridor street diagram, 90 foot right-of-way width, from StreetMix

SacCity motor vehicle parking

Dan AllisonLeave a comment

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so.

  • Street design will recognize that on-street parking may have a traffic calming effect, however, this effect will not preclude the use of existing parking for other purposes, including but not limited to wider sidewalks, bicycle facilities, parklets, street dining, bicycle and shared mobility parking, planting strips or parking lane trees, and transit lanes
  • Where current streets with parallel parking have excess width that encourages speeding, one or both sides of the street should be converted to diagonal parking; new diagonal parking will be back-in
  • Parking design will offer dedicated loading and delivery zones as needed; and will include time-limited green curb as needed by businesses
  • Parking spaces will be sized for normal passenger vehicles; oversized width or length vehicles may be restricted to certain spots or areas which are designed for them
  • Parking areas of streets need not be maintained to the same level as travel lanes

Parking Management

  • Parking will be managed and priced so as to create about 15% open parking on every block
  • Free parking will be eliminated throughout the city; where metered parking is not practical, parking permit fees will be set at a level that recovers the complete expense of parking space installation, maintenance and management

▾ Design diagrams:

  • Parallel marked and unmarked spaces
  • Diagonal parking (back-in)
  • Curb and pavement markings for prohibition (red), loading (white), delivery (yellow), and time limited (green) parking
diagonal parking on 26th St, Sacramento
diagonal parking on 26th St, Sacramento

SacCity signal management

Dan AllisonLeave a comment

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so.

  • Signal cycles will be the shortest timing consistent with ample time for walkers to cross
  • Shorter crossing distances and therefore shorter signal cycles can be created via lane reductions and curb extensions 
  • Signalized intersections will be evaluated for signal elimination and conversion to stop-controlled intersections
  • Leading pedestrian intervals (LPI) will be installed at all signalized intersections with pedestrian signals; LPIs will be a minimum of three seconds, longer in high pedestrian crossing areas
  • All pedestrian activation buttons will be removed, or will be converted to audible-only signal activation. Temporary signing will be installed when a button has been deactivated but not yet removed.

I earlier posted on too many traffic signals? in the central city, which should be eliminated in favor of stop controlled or yield controlled intersections.

SacCity sidewalk design standards

Dan AllisonLeave a comment

I’ve written about existing sidewalk buffers or lack thereof (sidewalk buffer widths), and a solution for areas without sidewalk buffers (street trees in the parking lane), and now on to sidewalk standards. Sidewalk areas are composed of the sidewalk, sidewalk buffer (also called planting strip or furniture zone), and pedestrian scale lighting.

Design criteria:

  • All new or reconstructed streets will have sidewalks, sidewalk buffers, and pedestrian scale lighting
  • Reallocated or mitigated streets will have sidewalk buffers added if right-of-way can be reallocated
  • Sidewalk areas may also include sidewalk-level bicycle facilities
  • Attached sidewalks (sidewalk adjacent to the curb) will not be used for new or reconstructed streets
  • Sidewalk width:
    • Minimum sidewalk width will be six feet in areas of 85% of more residential
    • Minimum sidewalk width will be eight feet in all other areas
    • Sidewalks must be completely free of obstructions, encroachments, or driveway aprons into their minimum width
    • Sidewalks adjacent to and within 1/8 mile of schools will be a minimum of 8 feet; sidewalks used for drop off/pickup will be a minimum of 10 feet
  • Sidewalk buffer width:
    • Minimum sidewalk buffer width will be eight feet in order to accommodate a canopy of mature trees; if a lesser width is available, parking areas will be considered for tree placement
    • Sidewalk buffer may also accommodate street related infrastructure and utilities, street furniture, bike and scooter parking, dining areas, bioswales, and other related uses
  • Sidewalks will receive priority use of right-of-way; travel and parking lanes, and bike facilities, will be placed in remaining right-of-way
  • Bus stop amenities will not be placed within the sidewalk minimum width; the sidewalk buffer may serve as clear sidewalk abutting the curb, with appropriate design and transition; transit amenities may also be placed on transit islands away from the sidewalk and sidewalk buffer
  • Sidewalks will be continuous over driveways and alleys, without interruption of design or materials
  • Pedestrian scale lighting will be provided along the street length; motor vehicle scale lighting will not be considered sufficient; intersections and crosswalks may be lit with motor vehicle scale lighting

Design diagrams:

  • Sidewalks of six or eight feet, with sidewalk buffers of at least eight feet
  • Tree planters or wells in the parking lane or curb extensions
  • Alley entrances and sidewalk crossings of alleys
  • Driveway crossings of sidewalk, with design indicating walking priority
  • Bus stop amenities (benches, shelters, etc.) with a sidewalk area clear of encroachment
  • Transit island diagram here or in the transit section
walkers at Capitol Park sidewalk N St & 15th
walkers at Capitol Park sidewalk N St & 15th

SacCity street design for transit

Dan AllisonLeave a comment

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so.

The purpose of designing streets for transit is to actively shift trips away from private motor vehicles and to transit. Most arterial streets in the city should have dedicated bus rapid transit design, and any street with more than one general purpose lane per direction should have a dedicated bus lane, with red paint.

  • Transit Street Design Guide will be used along with close collaboration with the transit agency to determine optimal and innovative street designs supportive of transit
  • Dedicated bus lanes will be provided on all 15-minute frequency bus routes on streets over one lane per direction
  • Light rail will be given exclusive right-of-way on streets with three or more lanes existing; and considered for streets with two or more lanes existing
  • Bus bays which force buses to pull out of and into traffic will not be used, except where the transit agency has identified the need to wait for a timed stop or to layover
  • Curb extensions may be lengthened to provide in-lane bus boarding
  • Dedicated bus lanes shared with bicyclists will be used only when high quality bicycle facilities on an immediately parallel street are not available, or to solve right-of-way issues of one block or less
  • Bus routes with 15-minute or better frequency, and light rail, will have transit signal priority at all intersections

Design diagrams will be developed in cooperation with the transit agency:

  • Bus stops, including stop amenities, with preservation of sidewalk passage
  • Concrete bus pads to lessen pavement deterioration
  • Bus boarding extensions on streets without bike facilities
  • Bus boarding islands with bicycle facilities behind, including design features that slow bicyclist traffic behind the island to prioritize walkers
  • Raised platforms for low floor or level boarding of light rail vehicles
  • Bus rapid transit streets, including potential raised platforms

SacCity street design for bicycles and shared mobility

Dan Allison5 Comments

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so. See also separated bikeways and bus routes, sidewalk-level bikeways, and bike lane widths.

  • Bicycle facilities will be provided within 1/4 mile of every origin/destination
  • Regular bike lanes (Class 2) may only be used where design and posted speeds are 30 mph or less
  • Separated bikeways (Class 4) will:
    • be used for design and posted speeds above 30 mph
    • have a minimum width of 8 feet, to accommodate passing and wider devices
    • use hard curb protection where parking protection is not available, or parking utilization is low
  • Signals
    • Bicycle signals will be used as necessary to ensure safe crossing of intersections, appropriate priority for bicyclists, and safe transitions to and from separated bikeways
    • Signals at intersections will detect bicyclists in any lane
    • Streets that host large volumes of bicyclists in general purpose lanes or bike lanes will have signal timing for a green wave, accommodating bicyclist speeds of 12-15 mph and slowing motor vehicle traffic
  • Parking
    • Parking for shared mobility devices will be provided in sufficient quantity on wide sidewalks (over 8 feet) or in the street
    • On-demand bicycle parking (BikeLink or equivalent) will be provided at locations where bikes are commonly parked for more than two hours
    • The city will work closely with transit agencies to ensure that bus stops with significant bicycling first mile/last mile have sufficient bike parking
  • Transit
    • All bus routes with 30 minute frequency or better will have bus boarding islands with bike lanes or separated bikeways passing behind the island; shared bus/bike lanes will only be used to distances of not more than one block, in order to solve right-of-way issues
  • Streets that provide long distance travel on with low volume and low speed motor vehicle traffic will be designated as bike boulevards, with appropriate marking, signing, and traffic calming treatment
  • Shared mobility will be managed and/or owned by the city or transit agency with sufficient control to ensure social and transportation objectives, and stability

Design diagrams will include:

  • Bike lanes (Class 2)
  • Separated bikeways (Class 4)
  • Bike boulevards
  • Contra-flow and two-way cycletracks, for use where safe bicycle facilities are not 
  • available on an immediately parallel street
  • Sidewalk level bike facilities
  • Bicycle signal faces
  • Bicycle detection at signalized intersections
  • bus boarding islands

SacCity design speed

Dan AllisonLeave a comment

Note: A reader asked how a driver would know whether they are on a street where the design speed is well above the posted speed, or whether they were on a street where the design speed was equal to the posted speed. That is a reasonable question. A safely designed street communicates through design what the intended speed is. However, our traffic engineering profession has trained drivers very well with the expectation that it is safe to exceed the posted speed. There will be a transition period as drivers learn 1) to pay attention to the street and what it signals, not just what the sign says, and 2) that new and reconstructed streets are designed for safety of all users, and therefore the design speed equals the posted speed. But in the meanwhile, drivers will need to know. So, I’ve added a sign below that could be used to signal design = posted, with a red border. The color of the sign itself can’t be changed because in our sign system (MUTCD), white is regulatory.

Part of an ongoing series of posts to support better streets in the City of Sacramento during their 2023 update of Street Design Standards. New standards must be innovative, safe, and equitable, and it will take strong citizen involvement and advocacy to make them so.

Streets are designed for a specific speed limit, which is almost always well above the posted speed limit. The original theory was that designing for higher speeds would protect drivers who drive over the posted speed limit. This is outmoded thinking, for two reasons. One is risk compensation, that most drivers will drive at a speed that feels slightly unsafe, so they are driving just over the design speed. Two is that even if the design speed is safe for drivers, it is not safe for walkers and bicyclists.

The points below are policy, not specifically designs. I have realized that it is not just the design standards that need to be updated, but the policies that determine what design will be used in various context. A lot of city policies are not documented, but reside in the minds of the planners and engineers. Because they are not documented, the public can’t evaluate them and ask for changes.

  • Design speed = posted speed; a street will never be designed or reconstructed for a higher design speed than the posted speed limit
  • Design and posted speed limits will be set at a level that ensures safety for all street users including walkers along and crossing the street, and bicyclists
  • All projects that reconstruct or reallocate a street must consider a reduction in the design and posted speed
  • Lane widths must match design speeds; lane widths will be limited to 9 or 10 feet except that one lane on truck routes, bus routes with 15 minute or better frequency, or dedicated bus lanes may be 11 feet
  • Local streets will have a design and posted speed of no more than 20 mph
  • Streets intended for both local and through traffic may have a design and posted speed of up to 30 mph
  • Streets will not be designed or posted for 40 mph unless the design reduces intersections, and reduces or eliminates driveways and turning movements
  • No street in an urbanized area will be designed or posted over 40 mph

street design contexts

Dan Allison3 Comments

People have commented on my series of street design posts, online and Twitter and in person, with many questions about how to fix existing streets. My focus so far has been on new and reconstructed streets. Obviously fixing existing streets is a critical issue, and I’m not wanting to neglect it, but part of my approach is summed up as “don’t build stupid”, in other words, don’t ever again design or construct a single transportation infrastructure that prioritizes motor vehicle traffic over access and safety for walkers and bicyclists. The best time for better design was 50 years ago, the second best time is today. But the City of Sacramento, and most cities and counties and state agencies, are continuing to build things that are hostile to people walking and bicycling. Traffic engineering is a remarkably regressive profession, sticking with what was once thought to work, even though it never did, and even though it is absolutely clear that it does not meet our needs today. Transportation infrastructure is meant to last 30 to 50 years, and may be in place longer than that, so everything we do wrong today will be around for a long time. We won’t ever have the money to fix everything (a lot of our transportation investment is basically money we’ve flushed down the toilet), and the Vision Zero or Safe Systems approach of identifying and fixing the locations with the highest fatality and severe injury crashes is right.

My thinking about street design has four contexts:

Read More »

street trees in the parking lane

Dan Allison3 Comments

Note: Added two photos to the bottom, or integrated parking and trees.

In situations where there isn’t any space for trees along the street, usually where a sidewalk buffer (planting strip) was never provided and where a reconstruction of the street to add sidewalk buffers is not in the budget or possible in the right-of-way, trees can be placed in the parking lane. I am not suggesting here that the entire parking area be replaced with trees, but there some trees and their associated shade for walkers and traffic calming effects could be provided on any street with existing parking.

Portland (PBOT) has a sheet about street tree enhancements, which includes Tree Planting in the Curb Zone:

Tree planting in the curb zone allows for encroaching into the on-street parking zone to increase planting widths. This offers an alternative method for increasing tree well size without negatively impacting people walking.

This new tool provides an opportunity to plant trees along curb tight sidewalks or where the furnishing zone is too narrow for large street trees, locations where tree planting would not be possible under current guidance.

PBOT Pedestrian Design Guide
PBOT Pedestrian Design Guide trees in the parking lane diagram
PBOT Pedestrian Design Guide trees in the parking lane

San Francisco has a Parking Lane Planter page:


Parking lane planters are landscaped sidewalk extensions placed between parking spaces at regular intervals or at specific locations. They provide space for street trees and landscaping on streets with narrow sidewalks, where tree planting is limited by conflicts with utilities or driveways, or where there is a desire to visually narrow the roadway.

SF Better Streets

It does not seem as though most cities have policies about placing trees in the street, and those that do, do not seem of long standing, but certainly the practice exists. Street trees in general, though, are of long standing, with every city having policy and design guidance. Sometimes urban forestry and transportation policies and transportation are well integrated, but as often, not.

The City of Sacramento does have an inventory of trees on city property, which includes planting strips (sidewalk buffers). I don’t know of any trees in the parking lane in Sacramento.

Two readers pointed out locations in Sacramento where parking and street trees are mixed in. Both of these were designed this way; the trees were not added later. Both are on R St, the first with a housing development, with parallel parking, the second with housing and commercial development, with perpendicular parking.

R St between 25th & 26th, south side, parallel parking and trees
R St between 25th & 26th, south side, parallel parking and trees
R St between 16th & 18th, south side, perpendicular parking and trees
R St between 16th & 18th, south side, perpendicular parking and trees