ORDER NO• 25717 ITEM No• 2.3 COMMISSIONERS' COURT AGENDA 9 _ g:00 A.M• REGULAR JANUARY 11~ 199 MONDA`I r ' d I If 1 1 :: .I 11# N GRDGR htiG. i_J'1? AF'RRCi'JAt_ GF USING CURP~ AND GUTTER ^N ROADS Ihd CYF°RESS SF'RIPJGS EST(;TES, F'HASE I On this the 11th day of Janl_~ar^y i.99'7, 1_>.pon oration made by Cvsrmissivnsr Griffin, seconded by Commissioner, Let._, the Cvl_irl: lananimously approved by a vote of 3-0-Q~, the I_ise of cl_~rb and gl_ttter an the cvl_intr•y Ianes in CyAress SF~rings Estates, F'h<-+se I. i rf .l ~ !li I 1 .. ,~.IN W ~tSSIQNERS- E-QUE2T ~~4 ft~Q-t#F,ST '~' `PtEi4SEFl-JRNISH ONE-ORf61NAt AND FWECOPIES OF~THIS REQUEST ~1ND DOCUMENTS TO BE REVIEWED BY THE COURT MADE BY: FranktirrJohnsorr. ~E MEETING DATE:.lanuarv 1~,. 1999 OFFICE: IEerr Eonnty Road-~ Brides TIME PREFERRED: St1BdECT: fPLEASEBE-SPECIFIC} eiariC>rxtiarorrCwr+essSor;ns~aEstates. PhaseEFtoad ~~yariartses-ando!},er issues: EXECF~TIVE SE$SIOflF REQUESTED: 1fES ~-^~ NO- PtE~tSES-T~rTE REASON: Ciarifnrrof Donst~orryariarioesrrn e,rrness sam~ts Est~ies. Phase I ESTIMATEI:1 LENt~TH OF PRES€N-TATIOI~: 20 minutes PERSONNEL MATTER -NAME OF EMPLOYEE: NAME E}F PERSON. ADDRESSING THE COURT: Time for submitting this request for Court to assure that the matter is posted in ac~oniance with Title 5, Chapters 554 &553 sf ttH}f a~vert~menE Code is as ~eetirps tattd ar> 2nd ~ ~'" tiAondaY= 5~ .!R ~revious'fuesday kAeetingstretd orrThnrsday: 5:Ot} P.hlF. previous Thn~sday THIS REQUEST RECEWEf} SY: THIS REQUEST RECEIVED ON: [~ A1tAgends RequestswitttJe screens by th~rCaantyJudge's-Oflicstardetennine if ade~uat~informatiorr hasbeen prepared for the Court's formal consideration and action at time of Court meetings. ~ Your cooperattorrwitttreappreciatedarr~co~yoarr~uest-being addressedarthe-ea~liest opportunity. See-Agenda Request Guidelines. ti '71 i 111 I I„~1"1A r-~ ~~>1•r ~~ul~g ~aad & -age 461 San Antonio Hwy ~, ~so2s Phone: 83t1`Z57--2993 FAX 83~~96-8a8r TO: Commissioners' Court FRf)Ivf: Framk}in Johnston; P:E., CountyEr-gi~-eer Date: January 4, 1999 RE: clarification-oa cypress Springs Estates, PhascF Road Eonstruction ~ariance~ and Other Issues Theo~ssionerscourt uc I998-granted-Cypress Springs Estates; Phased two variaQces: a} A}low "paved-oo-mtry lane" specifications on cul=d~sac-roads instead of "local roads" b} IJse-on-site ca}icheinstea~ofcrushedlimestoneforroa~base-mat~c~ial. 2. Cypress Springs Estates, Phase I is now considering using curb and gutter on roads as a wap to cantro~drainage-iirthe-sabdivisio~ a~ is requestingavarian~ce to their variance, specifically using curb and gutter on a paved country lane with 20' wide paved surface-instead-o~ 30'. The only reference I can find to a paved road with club and gutter is to an "alley." The mirtimumirraresideritial-area-should-be-t~vo 9-' widelanes and two 7' widcpar~llel parking areas according to "A Policy on Geometric Design of Il'ighways & Streets, 1990, AASI~TEl; Pagt436. Thisaddsup-to-3-2'. Appendix IE, RerrEounty Snbdivisionl~ules shows 30' wide for Local Road. I wouM-ra~end -the 30' wide-to-faxof curb dimensierr should be the murimum-width for any road with curb and gutter. The "paved country lane" classification came about for the large lots ora limited- number- of lots f t5 orless): Cuurtr and gutter oz} this classificatiorrofrood was not contemplated. ,~•`. ~. .,, .: . ,..;gyx~. __ __.. iYCIATtM1IIR.KM~MYU. lE14V ii0/. i161i/iili :_F j. j `. i ~P. .. ,. ' ' 'R ICcrr Courtly Cquunissions Court '°~' Kerr County Courthausc Kerrville; Texas°:~~OL~ ~ .. ,: •- ' . Commissioners: , , .- ;. ~: , , ,, • . ~ :. iy Rar~'~ My cltenls, I~i~.~ bee~agcl Gary Moran are respectfully requesting a variance from specific road s~cctfications as they would apply to _ etr properly intended for development. ~'""' The o~mers have prepared a pr+eliminaryplat for Phasc'I of Cypress Springs Estates (see°accompauylag a~".`~I'he roads for this deyelo~men~, are Fto; bepnvately o-med and privately maintained by :the ptopertykmmeisry~ocalion. Tlieie is a gated,enlcy,planned for aocas.of State Higlmay No. 39. The roads and road classifications for the'proposed Phase I are as follows: .. _ __., __ ~_. . Cypress Springs Road -Local Road . Cypress Mill Road -Paved Country Lane Cypress Garden Road -Paved Country Lane ~'^ Cypress Road -Paved Country L.anc TI-e roads will be built to Kcrr County specifications Cor courtly lanes and loc~~l roads. The o-mcrs arc requesting one exception from the speciti~tious for lo~l roads. The bast material specs for these roads includes Type C, Grade 2 material (crushed stone). TI-c owners would like to use the bast material for country lanes - pliche Grade 3 - to build this local road. Mr. Moran has hired n soil telling lab to a-t<~lyzc base material found on the propcriy. I am enclosing copies of these test rauhs for your review. Please vole Uu~l this material tested very closely to the specs for Grade 2. In considering this nxlucst for a variance from tl-c crushed stout requirement for base material, the o~mers make the following points: 1. The road will"bc private and privately maiulaincd. 2. The road will have a gated entry. 3. The road only scn~cs this dcvclopnunl and accesses no adjoining propcriy. 4. On-site road material has been tested with favomblc results. Thank you for your time and considcr.-tion of this matter. Sincerely, !'` ~~,~ Lcc C. Voclkcl ti 1 i71 :III ~ 1,111d~ ,. .:~.~ .f x•. ~. . ORDER N0. X5545 r ~'lt~~E r APPROVAL OF PRELIMINARY PLAT OF CYPRESS SPRINGS "'~~ ,.^^. SUPDIVISION, PRECINCT 4 AND GRANT VARIANCE On this day the 14th day of September, 1998 upon m.a.tion made by Commissioner Oehler, seconded by Judge Densort,~.the-C6:urt ~e approved by a vote of 4-1-0, with Commissioner Baldwin'.. ia. apposing, the preliminary plat of Cypress Spr-ings;.,'eubdvisian, z~~ , , Precinct 4 and grant variance to use on-site mat:er'ia1-;.to build roads the same or close to same q~.iality as Type,2 Crushed Base and access r^oads will be at a 90 degree ari~le and include a notation on the plat that this subdivision is a gated community. ,~^, r^ 1 ~ i ~i ~~ r ~7~u ~+~~ xu uAr s~V e5L5Y~ItlY~Je ~ dUroV is u uN~J D DATE: December 28, 1998 MEMO TO: Frank Johnston FROM: Lee C. Vcelkel SUBJECT: Cypress Springs Phase One Road Construction Frank: DEC 3 0 ~~--~ ~ ~ . a fat a. The owners/dcvelopers of the above referenced project request to be on the agenda of the next Commissioner's Court meeting scheduled for January 11, 1998. They would like to discuss road construction for their roads in the proposed subdivision. Through previous meetings of Commissioners Court the roads have bcen classified as follows (see accompanying plat for road names and location): Cypress Estates Pazkway -Local Road Glen Lakes Court -Paved Country Lane Oakhampton Trail -Paved Country Lane i'"` Cranbrook Court -Paved Country Lane The owner/developer is proposing curbed streets for all roads. The local road will be built according to the specs listed in Appendix K of the Kerr County Subdivision Rules and Regulations (05/11/98). There are no specs for "curbed" country lanes. Please review the enclosed cross-section for the type of road proposed by the owner/developer Note that the proposed pavement width exceeds We width of pavement for a country lane. Also note that these curbs will be "roll-over" curbs that will allow cars to pull off the road for parking. Please let us know if there is additional information you need prior to putting this item on the agenda. Thank you. r` .~ 9-It2 REF --'" 3f8 - ~., 24 R t0 1 1 1 .,._~--_~-~ 24 24 R 3 tt2 6 too 518 srArt: TEXL•`.rtals, collectors. and local access routes, detailed discussion of which appears 1 {~~R:i I I s .e trains, ands ' . t#' : '` in Ghapta L,('ieometric design guides for arterial strxts'sie'given in CatSptEr y,.. irY -.. : ViI;==and those for collector streets are covered in Chapter YI.'It is. not practi- ;hould be the same'as the ~, cal to.etntmerate separate design guides for local streets~for each item.dis- ' ` '' r. cussed herein. Where there is a significant differenx, separate guide values ..- :~„~e design features of local urban streets are governed by practical Gmita- ~ t~itsto-;a greaters~ttent than those,of similar•roads,in:nual-areas.,'1'hetwro k ~bs `` ~ ouoinant design,otxitrols are.(1)•tht: type,and~exteat~ot'•atrban development fi , .,~ .,,:,, .r ere pertinent, traffic wltl3ts limitatiaos on rights-of-way, and (2) zoning ot,rogulatory restrictioas3 - Is and streets. Refs + the , .stroeta primarily are land cervix streets in iesidential areas. In such :; i and, for some .. `r~:' the overriding oonsidetatian into foster a safe.and pleasant atviron-: - ` ~ ,rffiia convenieaoe of the motorist is a consideratiaG# Other ~ ~ traffic cervix may be ate land service only in part, and featu . . -;;srs3lxt _: -x ,~uitatt:,: :, ~ .-e . X!~ :,r..: , ;;¢~sr ~,~tigti._. :4rti~tl~i• ~. ' vStreets StdV111g 1ndUat[lal Ot,00mmQrOial at'Ca6'(lfhE ~K~CIt>.lii8?: `~+~ o:~rolnmes; and vehicle loads tlit~x. 8r'~Y`~?l~`O°'tesidefitial •ned with r re ~ ~'fol ~ prope ~gafcl ,and different dimensional and structural design values are appropri- ;eneration on areas opened ' `. ~`Iitae, safety and service to traffic usually are the major design c~tmLt. '.~I i711 I. I.. ;l I11U 434 AASHTO-Geometric Design of Highways and Streets k Local Roads and St, Where a particular design feature varies depending on the area served, viz, Grades residential, commercial, or industrial, different guide values are enumerated for each condition. The designer should be apprised of local ordinances and Grades for local resolutions that affect certain design features. the surrounding ter percent. Where gr. design may become Design Traffic Volumes prevent erosion on • For streets in co Traffic volume is not usually a major criterion in determining the geomet- less than 8 percent; ric values to be used in designing residential streets. Traditionally, these dients should be en streets are designed to a standazd two-lane cross section but may be afour- To provide for p lane cross section in certain urban areas, as governed by traffic volume, be used for streets administrative policy, or other community considerations. 0.20 percent may E For streets serving industrial or commercial areas, however, traffic vol- ume is a major factor. The DHV projected to some future design year should be the basis of design. It usually is difficult and costly to modify the geomet- Alinement ric design of an existing street unless provision is made at the time of initial a r construction. Design traffic in these areas should be that estimated for at least Alinement in re 10 years, and preferably 20 years, from the date of completion of phy to minimize t1 construction. an advantage in re courage through t of the facility is, m Design Speed , = Street alineme, rate with the topo; Design speed is not a major factor for local streets. For consistency in Street curves s design elements, design speeds ranging from 20 to 30 mph may be used, the minimum rad~ depending on available right-of--way, terrain, adjacent development, and other Where curves area controls. ~ should never be le In the typical street grid the closely spaced intersections usually limit vehiculaz speeds, making the effect of design speed of little significance. Design speeds exceeding 30 mph in residential areas may require longer sight Pavement Cross distances and increased curve radii, which would be contrary to the basic function of a local street. , . Pavement cros • slope normally st ., dens adjacent to 1 Sight Distance steeper by about curb. Minimum stopping sight distance for local streets should range from 125 The center se to 200 ft depending on the design speed (See Table III-1). smooth transition Design for passing sight distance seldom is applicable on local streets. Chapter IV. a ;~ai t,atnu cigr~HighKnys and Streets ' ~ ~ ~ Local Roads and Streets 4.?5 ~ ng on the area served, viz., Grades wide values are enumerated iced of local ordinances and Grades for local residential streets should be as flat as is consistent with the surrounding terrain. The gradient for local streets should be less than 15 percent. Where grades of 4 percent or steeper are necessary, the drainage design may become critical. On such grades special care must be .taken to prevent erosion on slopes and open drainage facilities. For strcets in commercial and industrial areas, gradient design should be in determining the geomet- less than 8 percent; desirably, it should be less than 5 percent, and flatter gra- areets. Traditionally, these dients should be emphasized. section but may be a four- To provide for proper drainage, the desirable minimum grade that should overned by traffic volume, be used for strcets with outer curbs is 0.30 percent, but a minimum grade of erations. 0.20 percent may be used. areas, however, traffic vol- e future design year should ustly to modify the geomet- Alinement . made at the time of initial be that estimated for at least ~ Alinement in residential areas should fit closely with the existing topogra- ~e date of completion of ~' phy to minimize the need for cuts or fills without sacrificing safety. There is • _ an advantage in residential areas in purposely arranging the alinement to dis- courage through traffic. The alinement design should be such that the safety ~ of the facility is not reduced. Street alinement in commercial and industrial areas should be commensu- rate with the topography but should be as direct as possible. .treets. For consistency in Street curves should be designed with as large a radius curve as feasible, to 30 mph may be used, the minimum radius being 100 ft. nt development, and other ~' . Where curves are superelevated, lower values may apply, but the radius • ,~ should never be less than 75 ft fora 20-mph design speed. intersections usually limit ~'• l deed of little significance. as may require longer sight - Pavement Cross Slope d be contrary to the basic Pavement cross slope should be adequate to provide proper drainage. Cross slope normally should be as shown in Table V-5 where there are flush shoul- ders adjacent to the traveled way. Where there are outer curbs, cross slopes steeper by about 0.5 to t percent are desirable on the lane adjacent to the curb. . is should range from l25 The center section of the pavement crown may be parabolic to permit II[-l). smooth transition of cross slope. Further discussion of this element appears in livable on local streets. Chapter IV. I Y ~ ,i it ~~~ ~ I ~~ nl,~~ Y 436 AASHTO-Geometric Design ojHighruays and Streets Local Roads and Streets Superelevation I severe limitations, 4-ft lanes c. lanes in industrial areas. Add Superelevation is advantageous for street traffic operation, but in built-up ! should be at least 9 ft wide, any areas the combination of wide pavement areas, proximity of adjacent develop- percentages of trucks. ment, control of cross slope, profile for drainage, frequency of cross streets, ~ Where needed and where li and other urban features combine to make the use of superelevation impracti- parking lane at least 7 ft wide cal or undesirable. Usually, superelevation is not provided on local streets in ~ conditions of lot size and inter residential and commercial areas; it should be considered on local streets in cial and industrial areas, park industrial areas to facilitate safe operation. they are provided on both side Where superelevation is used, street curves should be designed for amaxi- Parking-lane-width determ mum superelevation rate of 0.04. If terrain dictates sharp curvature, amaxi- should include consideration t mum superelevation of 0.06 is justified if the curve is long enough to provide during peak hour traffic that , an adequate superelevation transition. Minimum lengths of superelevation ment concentrations. runoff are given in Table V-7. A detailed discussion of superelevation is found Where curb and gutter see in Chapter III. (See Table III-16J i I included as a part of the parkr Number of Lanes Median On residential streets in areas where the primary function is to provide , Medians provided on local land service and foster a safe and pleasant environment, at least one unob- "' ment and to act as buffer str, ~ ' structed moving lane must be ensured even where parking occurs on both with the traffic needs of the sides. The level of user inconvenience occasioned by the lack of two moving various median types appear lanes is remarkably low in areas where single-family units prevail. Local res- Openings should be situat idential street patterns are such that travel distances are less than 0.5 mi The shape and length of the ,• between trip origin and a collector street. In multifamily-unit residential and the vehicle types to be a areas a minimum of two moving traffic lanes to accommodate opposing traf- openings should be that of tl fic may be required. In many residential areas a 26-ft-wide roadway is typi- secting cross street or drive cal. This curb-face-to-curb-face width provides fora 12-ft center travel lane measured between the inner and two 7-ft parking lanes. Opposing conflicting traffic will yield and pause centerline of the intersection on the parking lane area until there is sufficient width to pass. 40-ft turning control radius t. In commercial areas where there will be several midblock left turns it may be advantageous to provide an additional continuous two-way left-turn lane in the center of the roadway. Curbs Streets normally are desi Width of Roadway width and for control of dra The curb should be 4 to 9 Street lanes for moving traffic preferably should be at least 10 ft wide. traffic control, and safety. Where feasible they should be ] 1 ft wide, and in industrial areas they should On divided streets the tyl be 12 ft wide. Where available or attainable width of right-of-way imposes ~+'idth of the median and the /'1 Y 1 I I ldl Local Roads and Streets 437 of Highways and Streets /~."~ Iperation, but in built-up pity of adjacent develop- quency of cross streets, superelevation impracti- Ivided on local streets in ~dered on local streets in i be designed for amaxi- ;harp curvature, amaxi- 1; long enough to provide ~ngths of superelevation .f superelevation is found ry function is to provide ~.rnent, at least one unob- parking occurs on both ~ the lack of two moving . units prevail. Local yes- es less than 0.5 mi Iti~ly-unit residential Immodate opposing traf- ft-wide roadway is typi- a 12-ft center travel lane Iffic will yield and pause th to pass. nidblock left turns it may two-way left-turn lane in Id be at least 10 ft wide. ~iustrial areas they should r of right-of--way imposes severe limitations, 9-ft lanes can be used in residential areas, as can 11-ft lanes in industrial areas. Added turning lanes where used at intersections should be at least 9 ft wide, and desirably 10 to l2 ft wide, depending on the percentages of trucks. Where needed and where limitations exist in residential areas, a parallel parking lane at least 7 ft wide should be provided on one or both sides, as the conditions of lot size and intensity of development may require. In commer- cial and industrial areas, parking lanes should be at least 9 ft wide; usually they are provided on both sides. Parking-lane-width determinations in commercial and industrial areas should include consideration for use of the parking lane for moving traffic during peak-hour traffic that may occur where industries have high employ- ment concentrations. Where curb and gutter sections are used, the gutter pan width may be included as a part of the parking lane width. Median Medians provided on local urban streets primarily to enhance the environ- ment and to act as buffer strips should be designed to minimize interference with the traffic needs of the land abutting the roadway. A discussion of the various median types appears in Chapter IV. Openings should be situated only where there is adequate sight distance. The shape and length of the median openings depend on the width of median and the vehicle types to be accommodated. The minimum length of median openings should be that of the width of the projected roadway of the inter- secting cross street or driveway. The desirable length of median openings, measured between the inner edge of the lane adjacent to the median and the centerline of the intersection roadway, should be great enough to provide for a 40-ft turning control radius for left-turning P vehicles. Curbs Streets normally are designed with curbs to allow greater use of available width and for control of drainage, protection of pedestrians, and delineation. The curb should be 4 to 9 in. high, depending on drainage considerations, traffic control, and safety. On divided streets the type of median curbs should be eompatible with the width of the median and the type of turning movement control to be effected. 1 1 .. xl ICY p ~~'` 438 AASHTO-Geometric Design of Highimys and Streets Steep-faced curbs 6 in, or higher adjacent to moving traffic lanes should be offset at least 1 ft. Where there is combination curb and gutter construction, the gutter pan width, normally 2 ft, should be used as the offset distance. Drainage Drainage is an important consideration in an urban area because of high runoff and the flooding potential. Surface flow from adjacent tributary areas may be intercepted by the street system. There it is collected within the road- way by curbs and gutters, ditches, etc., and conveyed to appropriate outlets. Where drains are available under or near the roadway, the flow is transferred at frequent intervals from the street cross section by grating or curb-opening inlets to basins and from there by connectors to drainage channels or under- grounddrains. Economic considerations usually dictate that maximum practical use be made of the street sections for surface drainage. To avoid undesirable flowline conditions, the minimum gutter grade should be 0.30 percent. However, in very flat terrain and where drainage outlet is unavailable, a gutter grade as low as 0.20 percent may be necessary. Where a drainage outlet is available, the inlets should be spaced to provide a high level of drainage protection in areas of pedestrian concentrations or where adjacent property has an unusu- ally important public or community purpose (e.g., schools and churches). For further details see the drainage section in Chapter III. Cul-De-Sacs and 1Lrnarotutds A local street open at one end only should have a special turning area at the closed end. This turning area desirably should be circular and have a radius appropriate to the types of vehicle expected. Minimum outside radii of 30 ft in residential areas and 45 ft in commercial and industrial areas are com- monly used. A dead-end street narrower than 40 ft usually should be widened to enable passenger vehicles, and preferably delivery trucks, to U-turn or at least turn around by backing once. The design commonly used is a circular pavement symmetrical about the centerline of the street sometimes with a central island, as shown in Figure V-2C, which also shows minimum dimensions for the design vehicles. Although this type of cul-de-sac operates satisfactorily and looks well, better operation is obtained if the design is offset so that the entrance-half of the pavement is in line with the approach-half of the street, as shown in Figure V-2D. One steering reversal is avoided on this design. Where Local Roads and Srree[s ~~'; ,. r-----{ ,.. idl, /t~-'~~~ ,t, ijr '°~ ` ; ~ i ~1 i i i ,.,. tlr ~ I~~. g,~ I 1~1,t~ I lil t I ;~ . -o- w, 'DES. VEHICLE' P wa-ao su a wa-so -~- crrtcu~aa `y'y ~~tl .r tr r rr r~ -f- L-TYPE _~~ ` RZT ~r rl, .t rrl ~r r ~ -9- T- TYP' 0 F gs55ENGEq ,IENI[LE SU SINGLE UNIT TgUCN W R-O SE41 Tq~ILER CONBINITION - In' WB-SO SEMI TR EILER COMgINITION- L= Figure V-2. Types of c~ 1 r,~~hwnys and Streets lficf^es should be suttL .onstruction, offset distance. ~a because of high cnt tributary areas ;;d within the road- ppropriate outlets. llow is transferred ag or curb-opening channels or under- m practical use be ndesirable flowline rcent. However, in a gutter grade as Nutlet is available, page protection in crty has an unusu- .and churches). For rurning area at the and have a radius srde radii of 30 ft al areas are com- widened to enable rn or at least turn circular pavement ~s with a central Im dimensions for ates satisfactorily offset so that the I if of the street, as his design. Where Local Roads and Streets /~ ~~ oz I I ED ~ t~,\ Ali 1 L / 7 tll ~I iii iii `,~~ ;' ~.t t I I I Ir;`. -a- -c- CIRCULAR y. I~t I I I I I I I I ~ ~ -f- L-TYPE OES VEN10.E4 W L P JO' 60' su so' loo' ~~- ''-~ ~r~ tl, .t 1 I 1 I ~;~ -7- T-TYPE 0 R TMSSENGER VEHICLE SV SINGLE UNIT TRUCK wB-O gwl TRLRER CUM&N~TION-MTERNE01>TES WB-SO SEMI TRAILER COMBINITION- LARGE SQUARE ENO -a- CIRCULAR- OFFSET "<-: ~ "Y ~~, 1'; ii ~ I -M Y-TYPE I 1 439 %` r i ~ 1 I 1 1 1 ~ I~t J 1 1 r T 1 ,I, ~~''JJ. II ; S:II Y 14 S11 Y It -b- SV~~ t ~ ~ R• ` VyT~ i ~~ itl III ~a CIRCULAR- ALL PAVED I ''1 ., ,~. r~~4 ~r~t -I' BRANCH Figure V 2. types of cul-de-sacs and dead-end streets. OES. VE NICLE~ R W P 30' b' Wa-10 42' 25' i t i E ~I ~I 4 ci j I 1 440 AASHTO-Geometric Design of Highways and Streets a radius of less than 47 ft is used, the island should be bordered by mountable curbs to permit the maneuvering of an occasional oversized vehicle. An all-paved plan is shown in Figure V-2E, with a 30-ft outer radius. [n this case, little additional pavement is required. If the approach pavement is at least 30 ft wide, the result is a cul-de-sac on which passenger vehicles can make the customary U-turn and SU design trucks can turn by backing once. A radius of about 40 ft will enable a WB-SO vehicle to turn around by maneu- vering back and forth. Other variations or shapes of cul-de-sacs that include right-of-way and site controls may be provided to permit vehicles to turn around by backing once. Several types (Figures V-2F to V2I) may also be suitable for alleys. The geometry of a cul-de-sac must be altered if adjoining residences also use the area for parking. Alleys Alleys provide for accessibility and service to each individual land parcel. They are characterized by a narrow right-of-way and range in width from 16 to 20 ft in residential areas and up to 30 ft in industrial areas. Alleys should be alined parallel to or concentric with the street property lines. It is desirable to situate alleys in such a manner that both ends of the alley are connected either to streets or to other alleys. Where two alleys inter- sect, atriangular corner cutoff of not less than 10 ft along each alley property line should be provided. Dead-end alleys should be provided with a turning area in accordance with Figure V-3. Curb return radii at street intersections may range from S ft in residenti- ally zoned areas to 10 ft in industrial and commercial areas where large num- bers of trucks are expected. Alleys should have grades established to meet as closely as possible the existing grades of the abutting land parcels. The longitudinal grade should notbe less than 0.20. Alley cross sections may be V-shaped with transverse slopes of 2.5 percent toward a center V gutter. Runoff is thereby directed to a catch basin in the alley or to connecting street gutters. Sidewalks Sidewalks used for pedestrian access to schools, parks, shopping areas, and transit stops and placed along all streets in commercial areas should be 1 Luca! Roads and Srre~ STANDARD 7l ~~ STANDARD a1~ huavs and Streets ed bxmountable ve outer radius. In ~h pavement is at «~er vehicles can ,y backing once. round by maneu- ~t-of-way and site ,y backing once. for alleys. The ores a15o use the dual land parcel. in width from l6 ,. e street property both ends of the two alleys inter- challey property d with a turning 5 ~ residenti- ~ h: ,arge num- . as possible the gal grade should ,cs of 2.5 percent ,itch basin in the 1 Local Roads and Streets o~ N 0 ~o STANDARD TURN'"' worn Figure W3. Alleys. 441 0 N O n ,hopping areas, 1 areas should be MINIMUM TURNING AREA STANDARD CUT-CORNERS ~.'` TYPICAL CURBED SECTION FOR PAVED COUNTRY LANE (Proposed) 60 fl. RIGHT-0F-WAY 1 26' Flexible Base - ~ 24' to Back of Curbs I ~20'Asphaltic Surface ('!tw Course Surface Try 4" Flexible Base 95% Std Proctor Density 4° Crown "Rollover" Curb & Gutter 4" Compacted Subgrade