street design manual - sandiego.govfrom the adjacent street, narrow and irregular sidewalk surfaces,...

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Pedestrian Design

PEDESTRIAN DESIGN

The 1979 Progress Guide and General Planstates that walking within an urban communityshould be a pleasant and enjoyable experience,an opportunity for healthful exercise and quietrelaxation on the way to work, shopping, or otherdestinations. Instead, the pedestrian must oftencontend with annoying vehicular noise and fumesfrom the adjacent street, narrow and irregularsidewalk surfaces, and a veritable obstaclecourse of poles, fire hydrants, and trashcontainers within the public walkway. Additionally,adequate street lighting for nighttime safety isoften lacking, especially at bus stops. Moreover,amenities such as shade trees, landscaping, andcomfortable seating areas are infrequentlyprovided in commercial districts where walking isthe normal transportation mode1.

The City of Villages strategy calls for aconvenient, efficient, and attractive multimodaltransportation system in which pedestrians,bicycles, and transit vehicles are accommodatedin addition to automobiles. This system shouldimprove mobility for San Diegans by providingcompetitive—even preferred—alternatives to theautomobile for many trips in the region. Thestrategy, as a policy, recommends: Promotepedestrian- and transit-friendly design of Citystreets2.

NOTE: This section of the Street Design Manualis derived from Planning and Designing forPedestrians, Model Guidelines for the San DiegoRegion, June 2002, prepared for the San DiegoAssociation of Governments by CommunityDesign and Architecture. The Pedestrian DesignGuideline section complements and supports theother sections of the Street Design Manual.

1. Progress Guide and General Plan, 1979.2. City of Villages Strategic Framework Element,Draft January 2002.

Who are Pedestrians?‘Pedestrian” is used throughout these guidelinesto include people who walk, sit, stand in publicspaces, or use a wheelchair, be they children,teens, adults, elderly, people with disabilities,workers, residents, shoppers or people-watchers.Pedestrian-oriented design is accessible designfor all people.

The principal issue in the design of a pedestrian-supportive street is how to allocate its space; i.e.:How much space is required to satisfy the needsof pedestrians; how much to create active publicspace for deliveries; and, how much to providefor parking, bicycles, and vehicular movement?

The following discusses the pedestrianexperience at street level, including street design,intersection design, sight distance, pedestrian-crossings, pedestrian refuge islands, sidewalksfor overpasses and underpasses and highwayon/off ramps, and pedestrian realm.

1. Understanding ADA & Designing forVarious Disabilities and Ages

The following discussion focuses on theaccessibility needs and requirements as definedby both federal and state (California Title 24)accessibility standards.

Millions of persons in the United States havesome sort of permanent or temporary disabilitycaused by injury, age, or illness. The Americanswith Disabilities Act (ADA) was signed into law onJuly 26, 1990. This civil rights law assures that adisabled person will have full access to all publicfacilities—primarily to public transit, publicbuildings and facilities, and along public rights-of-way. Generally, this involves removing barriers towheelchairs and installing accessible wheelchairramps.

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It is essential, however, the design of pedestrianfacilities take into account the abilities anddisabilities of ALL pedestrians. Mobilityimpairment is but one classification of disability,along with sensory deficits (the sight and hearingimpaired) and cognitive impairments—those withdiminished ability to process information,including language barriers.

A. Grades

1. There should be enough sidewalk cross slopefor adequate drainage. The maximum crossslope should be no more than 2 percent forcompliance.

2. Along walkways, pedestrian ways, and sharedpedestrian/bikeway facilities, long, steepgrades should have level areas every 400 feetfor the pedestrian to stop and rest. In areaswhere it is impossible to avoid steep grades,an alternative route should be provided.

B. Sidewalks

1. Minimum unobstructed sidewalk width shall be5 feet. (Exceptions may be made to aminimum of 3 feet because of right-of-way(ROW) restrictions, natural barriers, or otherexisting conditions. The minimum width shouldbe expanded when there is either a verticalbarrier fronting the sidewalk or a vehicle travellane.

2. If a sidewalk is less than 5 feet wide, thereshall be a 5 feet x 10 feet passing space every200 feet of length along the sidewalk.

C. Curb Ramps at Intersections

1. At new intersections, curb ramp should align inthe direction of crosswalks, with two per cornerat each intersection.

2. Curb ramps shall be installed in accordancewith the San Diego Regional Standarddrawings.

3. Curb ramps or full cut-throughs 48 inches inwidth minimum, should be provided atchannelization and pedestrian refuge islands.

4. Storm drainage inlets should be placed on theuphill side of the curb ramps to preventstanding water at corner.

D. Surfaces

1. All surfaces should be stable, firm, and slip-resistant with a minimum static coefficient offriction of 0.5.

2. Surface treatments that include irregularsurfaces, such as cobblestone, can be difficultto navigate and should be avoided within theprimary walkway area. Low profile texturedsurfaces are acceptable.

E. Eliminating Barriers for Disabled

Since 1971, the state of California has mandatedwithin Health and Safety Codes, section 19956.5,that sidewalks and walks shall be madeaccessible to and usable by persons withdisabilities.

In addition to the following guidelines, individualsections of the guidelines include discussionsand guidelines pertaining to ADA accessibilityissues.


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2. Street Design

At a site and detail design level, the design ofstreets must consider the mobility and safety ofthe pedestrian ensuring that maximizing trafficcapacity and speeds are not the dominantconsideration in street design, particularly inpedestrian-oriented areas.

A. Issues to Consider

General

• A prevailing condition in much of the SanDiego region is the location of buildings setback from the street, which can result in abuilt environment that encourages traffic totravel at higher speeds.

• While it can be important to buffer residentialneighborhoods from adjacent busy and noisystreets, the need to buffer should bebalanced with the need for pedestrians toeasily get from the neighborhood to transit oruses along busy streets.

• Excessively wide lanes encourage higherspeeds on streets that can then divide acommunity.

• Frequent curb cuts along a street bothimpede traffic flow and create more conflictpoints between autos and pedestrians, thusreducing the effectiveness of sidewalks as apedestrian realm.

• Throughout the San Diego region, there arecanyons and mesas that make pedestrianconnections difficult to achieve.

• The warm and mild climate in San Diegothroughout most of the year creates

opportunities to make pedestrian travel arealistic option for many people.

B. ADA Accessibility

• Pedestrian facilities must comply with ADAstandards and California Title 24, and takeinto account the entire range of disabilities.

• ADA accessibility requirements most oftenhelp to create a better pedestrianenvironment, particularly for seniors, as wellas for those with disabilities.

C. New Development vs. Retrofit

• The guidelines and standards describe theminimum desirable improvements in mostcases; and, in many cases, discussions oftrade-offs between different needs arediscussed to help the reader identify thecompromises that may be necessary in theretrofitting of existing streets anddevelopments.

• Improvements to accessibility shouldconsider both sides of the street.

• Neighborhoods evolve over time and thepublic right-of-way configuration has aninfluence as to what type of developmentoccurs.

• Prior to improvements to an existing street,utilities such as lighting, electrical and stormdrains should be identified and eitherincorporated into the design or relocated.

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D. Relation to Transit

• All streets that are directly served by transitshould also be designed or retrofitted to servepedestrians since there must be adequatefacilities to access transit.

• Streets, sites, and buildings within an areathat is walkable to transit stops should bedesigned or retrofitted to serve pedestrians.

E. Guidelines

1. Parallel routes serving all forms of traffic shouldbe considered when resulting curb-to-curbwidth may not accommodate all other forms oftraffic (i.e., a dedicated bicycle or transit lane, aparking lane, or a travel lane).

2. The number of pedestrian crossings should bemaximized in order to prevent a street frombecoming a barrier in the community.

3. More frequent intersections along arterial roads(even if they only provide right-in and right-outaccess for cars), coupled with an overallinterconnected system of roads within the gridof arterial streets should be built in newdevelopment. This will allow better transitcoverage and pedestrian access as well asimproved overall circulation and communityaesthetics.

4. Access Control Plans should be developed fornew and existing streets that consolidateaccess points to adjacent properties, eitherthrough local access lanes, shared easements,or establishment of access via less-busy crossstreets.

5. For retrofitting or improving existing rights-of-way, sidewalks should be constructed. Wherethe existing right-of-way is too narrow toaccommodate sidewalk construction,additional right-of-way or public walkwayeasement should be acquired or the existingroadway narrowed but maintained inaccordance with established minimumroadway standards.


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3. Intersection Design and Operations

The word “intersection” means more than just themeeting of two (or more) streets. It is the wherethe auto realm and the pedestrian realmconverge, sometimes in conflict. It is because ofthis that intersections are often the most vitalareas along a street notwithstanding that they arethe point of most conflicts between vehicles,pedestrians, and bicycles.

Intersections must be designed with pedestriansafety and accessibility in mind. If pedestriansare either prohibited from crossing ordiscouraged from crossing, walking as a mode oftravel is hampered. The spacing of intersectionsor crossing points is also an important element inthe creation of a supportive pedestrianenvironment.

This section describes how intersections can bemade more pedestrian friendly by reducingcrossing distances and improving visibility forboth the pedestrian and the driver. Detaileddiscussion of specific crossing designs andelements is included in the following PedestrianCrossings section.


General

• Pedestrians should be made as visible aspossible since multiple conflict points forvehicles and pedestrians exist atintersections.

• Intersections that limit the crossing distance,crossing time, and exposure to traffic tend tobe more acceptable to pedestrian travel.

• Drivers traveling at a slower rate of speedhave more time to process and react topedestrian conflicts at intersections.


• Pedestrian facilities, including curb ramps,signal equipment, etc., must comply withADA standards and California Title 24, andtake into account the entire range ofdisabilities.


• Prior to improvements to an existingintersection, utilities such as lighting,electrical, and storm drains should beidentified and either incorporated into thedesign or relocated.

• New intersections provide the opportunity toclarify new forms of traffic control that mayprovide a more pedestrian-friendly setting.


• The location and design of transit stops atintersections should consider the accessneeds of adjacent land uses that generatepedestrian demand for transit as well aspedestrian and traffic safety issues at theintersection.

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4. Sight Distance

More often than not, sight distance is discussedonly from the standpoint of the driver and not thepedestrian. This is of particular concern atcrosswalk locations where parked cars, utilitypoles, street furnishing or landscape can obstructthe line of sight for pedestrians.


General

• The sightlines of traffic approaching anintersection on a significant grade arecompromised.

• Streets that support pedestrian movementsallow for the placement of elements such astrees and medians with landscaping. Thepresence of such elements creates a slowerspeed environment that is more conducive topedestrians. These elements shall be placedin such a fashion that adequate sightdistance is provided for all users of the publicROW.

• Sightlines for vehicles at an intersection areaffected both by buildings, street trees, streetfurniture, etc., and by the location of the stopline relative to the intersection.


At all pedestrian crossing locations, persons inwheelchairs and small children shall be visible tothe driver with on-street parking present.

Relation to Current Standards and Practices

• AASHTO Green Book recommends a 90-degree angle of roadways wheneverpossible.

• The CalTrans Highway Design Manualdefines stopping sight distance requirementsbased on the approaching speed of vehicles(Section 201.3). These standards range from125 feet for speeds of 20 mph to 360 feet forspeeds of 45 mph.

C. Guidelines

1. Parking restrictions near crosswalks should beconsidered to remove potential obstructions tothe pedestrian’s line of sight, particularly thatof young children and those in wheelchairs.

2. When street furnishings or other objects thatobstruct view cannot be relocated, curbextension or other treatments should beconsidered.

5. Pedestrian Crossings

One of the most effective means of turning animportant corridor into a community “spine” or“seam” rather than a “divider” is providing for safestreet crossings. Guidelines for installation ofmarked crosswalks at uncontrolled intersectionsand mid-block crossings are contained in CouncilPolicy 200-07 Comprehensive PedestrianCrossing Policy.


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General

• The width of the street, the geometry of theintersection, the timing of signalization, andthe frequency of crossing opportunities allplay important roles in achieving apedestrian-friendly environment.

• Closing a crosswalk does not mean thatpedestrians will not continue to try to cross astreet in that location.

• Crossing opportunities should be provided atregular and convenient intervals.

• Marked crosswalks are useful in channelizingpedestrian crossing activity at specifiedlocations.

• Marked crosswalks identify appropriatecrossing locations for pedestrians and alertdrivers to the possible presence ofpedestrians.

• The use of marked crosswalks is generallyconsidered appropriate at signalizedintersections where pedestrian activityoccurs.

• Street width and traffic speed can bemitigated with the use of sidewalk pop-outs.

• Some pedestrians may becomeoverconfident or be less aware of vehicleswhen crossing in a marked crosswalk.Therefore, marked crosswalks should not beused indiscriminately.


• Appropriate ADA ramps should be providedat all pedestrian crossings and medianrefuge areas.


• Pedestrian refuge islands and pop-outs canbe effective retrofit improvements that servepedestrians who are unable to cross duringone signal interval or in situations wherethere are no pedestrian signals and the roadis excessively wide.

• Textured paving or speed tables are effectivemeans of retrofitting streets to encouragereduced speeds in a pedestrian orientedarea.

D. Relation to Current Standardsand Practices

• Details on innovative pedestrian crossingtreatments for both signalized andunsignalized intersections have beenpublished in a document by the Institute ofTransportation Engineers, AlternativeTreatments for At-Grade PedestrianCrossings, 2001. This source described anumber of measures, including thoseincorporating signing, striping, lighting,vertical displacement treatments, horizontaldisplacement, narrow lanes, curb extensions,alternative surface treatments, backdrops,overhead devices, in-pavement devices,signal equipment, pedestrian detection, etc.The study included the following conclusions:

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• There are a number of geometric designfeatures, such as curb extensions andpedestrian refuge islands, that can be usedto improve safety of marked crosswalks,especially those on high-volume, multi-lanefacilities.

• Areas of high pedestrian activity benefit mostfrom being designed in ways that promotepedestrian activity and afford pedestrians areasonable measure of comfort and safetywhen crossing streets.

• Lower speed streets, such as those found inactive mixed-use areas and residentialneighborhoods, allow the use of lesscomplex treatments such as signs andmarkings.

E. Relation to Transit

• All transit stops require that pedestrians beable to cross the street safely and withinproximity to the stop.

F. Guidelines

1. The width of crosswalks should be a minimumof 10 feet (3.0) wide. Unless small-scaleintersection conditions dictate otherwise,widths should be increased where there isgreater pedestrian activity.

2. Adequate lighting at the levels specified in thechapter on street lighting should be present.

3. Marked crosswalks should be considered foruncontrolled crossing locations if there are nocontrolled crossings (by a traffic signal or stopsign) within 600 feet of the proposed crossinglocation (provided that the other guidelinespresented here are met).

4. Marked crosswalks should be provided at allsignalized intersections where pedestriancrossing equipment is provided.

5. Marked crosswalks alone are insufficient (i.e.,without traffic-calming treatments, trafficsignals, pedestrian signals when warranted, orother substantial crossing improvementspresented in these guidelines) and should notbe used under the following conditions:(a) Where the speed limit exceeds 40 mph.(b) On a roadway with four or more lanes

without a raised median or crossing islandthat has (or will soon have) an ADT of12,000 vehicles per day or greater.

(c) On a roadway with four or more lanes witha raised median or crossing island that has(or will soon have) an ADT of 15,000vehicles per day or greater.

6. Special crosswalk markings should be used inorder to increase the visibility of the crosswalkand on uncontrolled approaches tounsignalized intersections. These specialmarkings are generally more appropriate onroads where the adjacent land use may divertdrivers’ attention.

7. Curb ramps (two per corner preferred) shouldbe provided at all crosswalks. If a raisedcentral median extends into the crosswalk, anADA-compliant channel must be providedthrough the median. A detectable warningsurface should be installed within the channel.

G. Residential Street Crossings

Issues to Consider

• Enhanced pedestrian crossings in residentialneighborhoods are a key component ofpedestrian-oriented street design and lead toboth improved pedestrian safety and the“livability” of the neighborhood.


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• Residential street crossings are oftencombined with traffic calming measures thatare designed to maintain low vehicle speeds,such as raised crosswalks, chicanes, andgateway narrowings. Refer to the TrafficCalming section of the manual.

• Enhanced pedestrian crossings in residentialneighborhoods may not be used if trafficvolumes are low enough that pedestrians arecomfortable crossing at any location.

Guidelines

1. Marked crosswalks in residential areas shouldbe warranted if traffic volumes exceed 2,000vehicles per day.

2. Enhanced pedestrian crossing measuresshould be considered in residentialneighborhoods where a demonstratedcrossing demand exists.

3. On residential streets that experienceexcessive vehicle speeds, enhancedpedestrian crossings should be combined withtraffic calming measures such as pop-outs.

H. Mid-block Crosswalks

Issues to Consider

• Mid-block crosswalks provide convenientcrossing locations for pedestrians when othercrossing opportunities are distant or wherethere is a presence of concentrated mid-block pedestrian crossing demand.

• As may be the case for crosswalks atintersections, mid-block crosswalks help toconcentrate pedestrian crossing activity andalert drivers to the possible presence ofpedestrians.

• Safety concerns arise at mid-blockcrosswalks as drivers typically do notanticipate pedestrians or crosswalks at non-intersection locations.

Guidelines

1. Mid-block crosswalks shall be installed inaccordance with Council Policy 200-07.

2. Mid-block crosswalks shall be well illuminated(refer to Street Lighting section).

3. An ADA-compliant curb ramp should beprovided at each end of the crosswalk.

4. Curb extensions may be considered at thecrosswalk to enhance pedestrian crossingvisibility and reduce crossing distance.

5. High contrast detectable surface should beinstalled on the sidewalk at each end of mid-block crosswalk (see Appendix IV ).

6. If mid-block crosswalks are signalized, audibledevices should be installed.

7. On streets that experience excessive vehiclespeeds, enhanced pedestrian crossingsshould be combined with traffic calmingmeasures, such as raised crosswalks or curbextensions.

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6. Pedestrian Refuge Islands

Pedestrian refuges in wide or busy streetsimprove safety for pedestrians and vehicles.They are defined as areas within an intersectionor between lanes of traffic where pedestriansmay safely walk until vehicular traffic clears,allowing them to cross a street. Another benefit topedestrians is that it can significantly reducedelay in crossing unsignalized intersections sincethe pedestrian need only search for vehicles inone direction at a time.


General

• Pedestrian refuge islands work well on widerstreets where there are long pedestriancrossing times and exposure to vehiculartraffic or on streets with speeds higher than35 mph.


• Particularly useful for slower pedestrians,such as the very young, elderly, or those withmobility disabilities.

• Where it is not possible to include ramps andwaiting pads that meet ADA requirements,waiting areas should be at-grade with theroadway (channels), although slopes shouldfacilitate drainage and planting or bollardsshould buffer pedestrians from moving traffic.


• Pedestrian islands may be installed atintersections or mid-block locations deemedappropriate through engineering studies.

• Pedestrian islands should be consideredfrom the outset of design for intersectionsthat are either complex, irregular in shape,excessively wide or in areas where childrenand older people are expected to crossfrequently


• The use of pedestrian islands should beconsidered where transit is “running” withinthe street right-of-way, particularly in stationareas.

E. Guidelines

1. Refuge islands should be a minimum of fourfeet wide by eight feet long.

2. Pedestrian refuge islands should be wellilluminated.

7. Sidewalks for Overpasses, Underpasses,and Highway On/Off Ramps

Access on an overpass across a highway is oftenalong a narrow sidewalk where the pedestrian isagainst a wall or guardrail and is highly exposedand vulnerable to speeding traffic. Theunappealing environment of underpasses is oftenexacerbated by poor lighting and obscuredsightlines. Pedestrian access across on- and off-ramps can also be difficult since the driver ispreoccupied with making the transition betweenthe highway and the street network.

The overpass discussion is applicable to allbridges with pedestrian access and the overpassand underpass discussions are applicable tograde-separated railroad crossings.


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A. Overpasses and Underpasses

Issues to Consider

General

• Overpasses and underpasses necessitateaccessible ramps that require a considerableamount of additional land for installation.

New Development vs. Retrofit

• Opportunities to widen sidewalks whenretrofits occur.

Guidelines

1. Minimum widths for walkways on over andunderpasses should follow the guidelines forsidewalk width.

2. Underpasses should have a daytimeilluminace minimum of 10 footcandlesachievable through artificial and/or natural lightprovided through an open gap to sky betweenthe two sets of highway lanes and a nighttimelevel of 4 footcandles.

3. Consider acoustics measures withinunderpasses to reduce noise impacts topedestrians and bicyclists.

B. Highway On/Off Ramps

Issues to Consider

General

• Pedestrian safety measures should beconsidered where drivers are in the processof “transitioning” from high-speed highwaysto local streets.

New Development vs. Retrofit

• Many existing highway access points havebeen designed with limited provision forpedestrian access along the local streets andthe resulting situations often leave little spacefor retrofit.

• New highway access improvements such asreducing the turning radii need to beconsidered to address pedestrian and bicyclesafety and access issues.

Guidelines

1. Free-flowing entrance and exit ramps shall notbe constructed in areas where pedestrians areexpected.

2. A right angle intersection should be providedwhere the ramp meets the cross street toimprove visibility for both the motorists andpedestrians as well as to reduce the crossingdistance.

8. Creating a Pedestrian Realm

Safe and direct sidewalk connections are of keyimportance to creating a pedestrian-friendlyenvironment. Sidewalks should support activitiesthat will occur in the area and provide acomfortable place for pedestrians to take part invarious activities. However, creating a high-quality pedestrian realm that supports andencourages walking takes much more thansimply providing sidewalks.

The design of the sidewalk and the elementswithin it and the location and design of buildingsare just some of the additional considerations ofcreating a pedestrian-supportive environment.Furthermore, walking provides moreopportunities to observe details than any other

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form of transport. Landscape and architecturaldetails are necessary, therefore, to sustaininterest for the pedestrians as well as to providea safe and comfortable experience.

A. Sidewalk Design

Sidewalks are not merely thoroughfares forpedestrians. They are also important socialspaces where people interact and walk together,catch a bus, window shop, or have a cup ofcoffee at a café. The sidewalk must be wideenough to accommodate movement in addition toamenities such as seating that facilitate socialinteraction. This makes the sidewalk morecomfortable and appealing, which can encourageuses that increase security.

B. Issues to Consider

General

• Existing excessive right-of-way widths alsoallow for widening sidewalks and on-streetparking, both of which significantly improvethe pedestrian experience.

• Increased buffering between fast-movingtraffic and abutting properties created bywider sidewalks or local access lanes makesthe street more attractive for buildings to frontdirectly onto the street.

• Provide appropriate sidewalk widths giventhe use and amount of activity that isexpected.

• Select materials with consideration formaintenance and long-term appearance.

• Minimize obstructions and conflict points.


• Dimensions of an existing sidewalk can beincreased either through the acquisition ofadditional right-of-way, zoning a setbackrequirement for new development to createadditional pedestrian space, or through areduction in curb-to-curb roadway widthwhere applicable. Another alternative toreducing roadway width in these cases couldbe to revise the parking from parallel todiagonal, which would slow speeds andcreate opportunities for improved pedestrianenvironment.

• New streets must balance the needs of allusers in determining right-of-way width.


• The ”footprint” of and access to transitfacilities such as bus shelters must beconsidered in the design of sidewalks.

• Sidewalks must connect transit facilities withthe adjacent uses within walking distance ofthe station or bus stop.

• Review MTDB publication, “Designing forTransit,” as well as these guidelines inrelation to pedestrian access to transitfacilities.

E. Establishing “Zones”

The Sidewalk Corridor is typically located withinthe street right-of-way between the curb andbuilding face and/or property line. The sidewalkcorridor is composed of four distinct zones: theEdge Zone, the Furnishing Zone, theThroughway Zone, and the Frontage Zone.


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1. Edge Zone

The Edge Zone (sometimes referred to as the“Curb Zone”) is the interface between theroadway and the sidewalk. At a minimum, thiszone includes the 6”-wide curb. In more active,mixed-use areas with on-street parking, this zoneshould be a minimum of 1’6” to accommodate thedoor swing of a parked car to prevent conflict withelements within the Furnishing Zone. At transitstops with shelters, this zone should be widenedto four feet to provide wheelchair access to theshelter. (In constrained conditions, transit sheltersare available with partially open sides, allowingthe Edge Zone to be reduced to 2’6”). Providing apop-out for the entire length of the transit stop isalso an effective way to increase Edge Zonewidth.

2. Furnishings Zone

The Furnishing Zone also accommodates streettrees and landscaping. It is the zone thatprovides the buffer between the active pedestrianwalking area, the Throughway Zone, and streettraffic. Street trees, tree lawns, street furniture,utility poles, phone booths, parking meters, firehydrants, bicycle racks, and the like areconsolidated in this zone to keep them frombeing obstacles in the Throughway Zone.Planting in this zone must comply with thestandards and guideline in this manual and theLandscape Technical Manual, particularly in thecase of street tree well dimensions. Theplacement of these aforementioned elementsmust comply with the Land Development Code,San Diego Municipal Code and applicableCouncil Policies.

Installing pedestrian pop-outs is an effective wayto increase sidewalk space for street furnitureand other features. The dimension of theFurnishing Zone must consider whether streetparking is provided (an effective buffer) and thespeed of traffic.

3. Throughway Zone

The Throughway Zone is intended for pedestriantravel only and should be entirely clear ofobstacles, including driveway aprons. This zoneshould be at least five feet wide. For highpedestrian volume areas, additional width shouldbe provided. “Overhanging” elements, such asawnings, store signage, bay windows, etc., mayoccupy this zone as long as there is a cleardistance under them of at least eight feet.

4. Frontage Zone

The Frontage Zone is the area adjacent to theproperty line that may be defined by a buildingfaçade, landscaping, or a fence. Generally,pedestrians do not feel comfortable moving at afull pace directly along a wall; and, because ofthis, the minimum frontage zone should be 1’6” inthese situations. This is also the zone wherepedestrians slow down and window-shop andenter and exit buildings. Adjacent businessesmay use this zone for outdoor displays andseating, and municipalities must ensure thatthere is adequate space to accommodate theseuses without impeding the Throughway Zone.

Architectural elements that encroach into thestreet, such as awnings, stairs, front stoops,artistic elements, planters, marquees, and thelike may also occupy this zone. These elementsadd vitality and visual interest to the street but,nevertheless, must comply with local, state andFederal Regulations.

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Where no Furnishings Zone exists, elements thatwould normally be sited there, such as benches,light poles, signals, trash cans, etc., may occupythe Frontage Zone in order to keep theThroughway Zone clear and maintain at leastminimum ADA requirements

Where the sidewalk passes a parking lot, thereshould be some type of buffer, such as a hedgeor a low wall in order to maintain a moreaesthetic frontage along the sidewalk andprevent parked vehicles from overhanging intothe Frontage Zone.


F. Public Art and Amenities

Pedestrian improvements create a uniqueopportunity where people can see and bepositively impacted by public art as part of theireveryday activities; they also help create morewalkable communities. Pedestrian improvements,which include public art, can convert ordinaryspaces into places of meaning. Improvementprojects constructed using public monies maydesignate a portion of their budget for public art.

Issues to Consider• On a large scale, public art has the ability to

unify a neighborhood with a theme, and at apedestrian level can provide visual interest forthe passerby.

• Public art is an effective means of creating aneighborhood identity, and ideally shouldreflect the character and history of thecommunity.

• Good design can encourage the use ofstreets for festivals, parades, and othercultural events that promote neighborhoodpride and a sense of place.

Guidelines1. Public art should be located so as to be a

pedestrian amenity without compromisingsafety.

2. When appropriate, consideration should begiven to commissioning artists to create uniquestreet elements such as light poles, benches,trash cans, manhole covers, tree grates, etc.

3. When appropriate, consideration should begiven to a design that is conducive to usingstreets for festivals, parades, and othercommunity events.

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Traffic Calming

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TcTraffic Calming

Traffic Calming

A. PurposeThis section is intended to provide design optionsfor traffic calming on new streets and streetsbeing considered for retrofit. Some generaldesign specifications are provided to assistdesigners in developing comprehensivestreetscape plans for proposed development andredevelopment projects. It is emphasized thatthese are just guidelines and that innovativestreet designs that incorporate traffic calming areencouraged.

B. OverviewTraffic calming involves the use of variousgeometric features designed to reduce vehiclespeeds or discourage shortcutting traffic. Toachieve the desired effect of traffic calming, theeffectiveness of such measures and their impactsshould be evaluated on an area-wide basis.

Landscaping, street trees, street lighting, andstreet furniture are other methods of trafficcalming that also create distinctive and pleasingstreetscapes that encourage sidewalk activity.These improvements may involve considerationof irrigation and long-term maintenance to beprovided by maintenance assessment districts orother agreements with the City.

Traffic calming is appropriate along circulationelement roads as well as commercial andresidential local streets. Local streets should bedesigned to function efficiently and safely, yetminimize the need for extensive traffic regulation,control devices, and enforcement. The function ofthe local street should be readily apparent to theuser through its appearance and design.

C. General GuidelinesThe following general guidelines should beconsidered in traffic calming installations:

• Delays to emergency vehicles should beminimized by the appropriate placement anddesign of traffic calming devices. In somecases, certain traffic calming devices may notbe appropriate.

• Traffic calming installations should not diverttraffic to other local residential streets. Trafficcalming installations should support thestreet classifications established incommunity plans. Traffic may be divertedfrom residential streets to classified throughstreets. The potential impacts of trafficdiversion should be evaluated for all trafficcalming installations.

• Traffic calming devices on designated transitroutes should be limited to those that permitthe efficient movement of transit vehicles.

• Traffic calming installations must meet Stateand Federal accessibility requirements.

• Traffic calming should not impair the mobilityof non-motorized users to of the street.

• Traffic calming installations must addressdrainage, sight distance, and location ofunderground utilities.

• All traffic calming installations are required tohave a landscape element that includes treesand shrubs consistent with the LandscapeTechnical Manual. If traffic calming devicesinclude decorative pavement, it shall complywith section E of the Design Standards in thisManual.

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Traffic Calming

D.Traffic Calming TechniquesTraffic calming strategies generally fall into sixcategories:

• Horizontal deflections (chicanes, mini trafficcircles, median slow points or chokers)

• Vertical deflections (road humps, speedtables, and raised crosswalks)

• Intersection pop-outs• Traffic diverters (semi-diverters)• Channelization

Enhancing the streetscape environment shouldhave the same level of priority in the designscheme as traffic calming impacts. A generaldiscussion of these categories follows along withmore specific details and design guidelines forvarious traffic calming techniques.

Traffic calming” features such as median slowpoints or chokers, chicanes, mini traffic circles,and intersection ‘pop-outs’ may be provided inaccordance with this design manual. Roadhumps or speed tables may be installed by theCity on existing streets under somecircumstances but should not be included instreet construction or improvement projects.

E. Horizontal DeflectionsHorizontal deflections are used to achieve speedreductions by breaking up the linear path ofvehicle travel. Traffic calming designs that involvehorizontal shifts in the travel way areinappropriate for major streets and arterials.Horizontal deflections include chicanes (mid-block) mini circles (intersections), and medianslow points (mid-block and intersections).

Chicanes - A chicane is a channelization thatcauses a series of tight turns in oppositedirections in an otherwise straight stretch or road.The combination of narrowed street width and theserpentine path of travel slows traffic. On newstreets, chicanes narrow the street by wideningthe sidewalk or landscaped parkway. On streetsconsidered for retrofit, raised islands are installedto narrow the street. The advantages of chicanesinclude: slow traffic, may create opportunity forlandscaping, and tends not to divert traffic tonearby streets. Chicanes are inappropriate foruse on streets classified as collector or higher,bus routes, emergency response routes, wherethere is a grade that exceeds 5 percent, or wherethere is limited stopping sight distance such as atthe crest of a hill. Chicanes may cause some lossof on-street parking, may impact driveways, mayincrease emergency response time, or may affectdrainage and street sweeping.

Mini Circles - A mini circle is a raised circularisland placed in the center of an intersection.Traffic yields on entry, then enters to the right,traveling around the circle counter clockwise. Amini circle slows traffic on each approach,reduces right-of-way conflicts, creates alandscaping opportunity, and tends not to diverttraffic to nearby streets. Mini circles are

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appropriate for usage on low volume localresidential streets with alternative access points.Mini circles should not be used on streetsclassified as collector or high, bus routes oremergency response route, where the gradeexceeds 5 percent on any approach, or wherethere is limited stopping sight distance. A minicircle may impact large vehicles’ turns or mayincrease emergency response time.

Median Slow Points - A median slow point is asmall median or island placed in the center of aroadway that causes traffic to shift its path to theright in order to travel around it. It may be on anapproach to an intersection or mid-block. Ifmedian slow points are installed at anintersection, the street should have alternativeaccess points. A median slow point slows traffic,creates a pedestrian refuge area, creates alandscaping opportunity, and tends not to diverttraffic to nearby streets. Median slow points maybe used on two lane streets. It should not beused on streets classified as major or higher orwhere there is limited stopping sight distance.Median slow points may cause some loss of on-street parking or may impact large vehicles’ turnswhen installed at intersections.

F. Vertical DeflectionsVertical deflections are an effective traffic calmingtechnique for speed reductions and discouragingshortcutting on local streets. Vertical shifts areonly appropriate on two-lane streets. Trafficcalming designs that involve vertical shifts areinappropriate for collector streets, major streetsand arterials. Vertical deflections include roadhumps and speed tables/raised crosswalks.

Road Humps - Road humps are rounded raisedareas placed across the road. Road humps areapproximately 12 feet long (in the direction oftravel), 3.5 inches high, and parabolic in shape. Itis usually constructed with a taper on each sidewithin a foot or two of the gutter line to allowunimpeded drainage between the hump andcurb. They are most effective when used ingroups that are spaced close enough to avoidencouraging speeding between humps. Roadhumps are different from speed bumps. Speedbumps are much more abrupt, usually less thanthree feet in length, and are used in parking lotsand private drives. Speed bumps are not used onpublic streets.

While primarily used for speed reductions, roadhumps can also result in the reduction of trafficvolumes on streets where they are employed bydiverting traffic to other nearby streets. Roadhumps should not be used on streets classifiedas collector or higher, emergency responseroutes, bus routes, where grade exceeds 5percent, or where there is limited stopping sightdistance. The disadvantages of road humps mayinclude diverting traffic to other low-volume localstreets, increasing emergency response time, orincreasing noise.

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Speed Tables/Raised Crosswalks - Speed tables,essentially, are flat-topped road humps, oftenconstructed with brick or other textured materialson the flat section. Speed tables are 3-1//2 incheshigh and 22 feet long in the direction of travel,with 6-foot ramps at the ends and a 10-foot fieldon top. The brick or other textured materialsimprove the appearance of speed tables anddraw attention to them. Speed tables are lessjarring than the standard 12 road humps. Speedtables are most effective when installed in groupsof two or more, about 300 feet apart. Whereextended from curb-to-curb and appropriatelymarked, speed tables serve as raisedcrosswalks. Raised crosswalks bring the streetup to sidewalk level. Drainage requirements mustbe evaluated and addressed where raisedcrosswalks are installed.

Speed tables and raised crosswalks reducevehicle speeds. Raised crosswalks enhancepedestrian safety. The disadvantages of speedtables/ raised crosswalks may include divertingtraffic to nearby low-volume local streets,increasing noise and increasing emergencyresponse times. Speed tables/raised crosswalksshould not be installed on streets classified ascollector or higher, emergency response routes,bus routes, where grade exceeds 5 percent, orwhere there is limited stopping sight distance.

G. Intersection Pop-outsIntersection pop-outs are curb extensions thatnarrow the street at intersections by widening thesidewalks at the point of crossing. They are usedto make pedestrian crossings shorter and reducethe visual width of long, straight streets. Whereintersection pop-outs are constructed bywidening the landscaped planting strip, they canhave a positive effect on the visual appearance ofthe neighborhood. Pop-outs can be used atintersections to create a street gateway effect,visually announcing an entrance to aneighborhood. Intersection pop-outs mustaccommodate bicyclists, transit vehicles andemergency response vehicles. Pop-outs improvepedestrian visibility, create shorter pedestriancrossing width, and may reduce vehicle speeds.Pop-outs may impact large vehicle turns, mayimpact accessibility by transit vehicles oremergency response vehicles, and may requireparking removal. Intersection pop-outs may beinstalled on local streets, collector streets, andurban major streets. Pop-outs are inappropriateon major streets and primary arterials. The entireintersection should be designed and constructedat one time.

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H. Traffic DivertersTraffic diversion devices eliminate through tripson streets on which they are installed and divertthose trips to other streets. There are severalavailable traffic diversion designs that may beused to calm traffic. Traffic diverters are notprimarily installed for the purpose of speedcontrol. Diverters are best suited on long,straight, low-volume, local residential streets.Wherever traffic diversion techniques areemployed, provision should be made forcontinuation of pedestrian and bicycle routingaround or through the diversion. Care must betaken in design of diversion installations to allowfor emergency vehicles.

Semi diverters. - A semi diverter is a barrier totraffic in one direction of a street that permitstraffic in the opposite direction to pass through. Itis an alternative to one-way street operation for ablock and it allows residents on the block limitedtwo-way travel opportunity. A semi diverter maybe used on low-volume, local residential streetsand it is best located at the end of a block toprevent entrance and allow exit. Semi divertersreduce cut-through motorized vehicle traffic,reduce pedestrian crossing widths, and createopportunity for landscaping. Semi diverters maydivert traffic to other low-volume streets, mayincrease trip lengths, may cause loss of parking,and may increase emergency response time.Semi diverters are inappropriate for use onemergency response routes, bus routes, orstreets classified as collector or higher. Nospecific geometric features are included in thismanual since semi diverters are site specific andshould be designed on a case-by-case basis.

I. ChannelizationChannelization may be used on arterial streets toprevent cut-through traffic onto local streets or tocontrol turning traffic in or out of a neighborhood.Channelization can be achieved throughregulatory signs and pavement markings,landscaping, or raised channelization islandsaimed at motorized, non-motorized, or pedestriantraffic. Channelization may be designed toprevent cut-through traffic, reduce speed, createopportunity for landscaping, control turning trafficin and out of a neighborhood, or physically guidepedestrians. The disadvantages of channelizationmay include creating out-of-direction travel,increasing trip lengths, increasing emergencyresponse time, or impacting accessibility. Nospecific geometric features are included in thismanual since channelization devices are sitespecific and should be designed on a case-by-case basis.

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New Installations Retrofit Installations

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street design manual - sandiego.govfrom the adjacent street, narrow and irregular sidewalk surfaces,...

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