Highway Design C E 427
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This 52 page Class Notes was uploaded by Charley Wintheiser DVM on Monday October 5, 2015. The Class Notes belongs to C E 427 at California State University - Long Beach taught by Shadi Saadeh in Fall. Since its upload, it has received 14 views. For similar materials see /class/218763/c-e-427-california-state-university-long-beach in Civil Engineering at California State University - Long Beach.
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Date Created: 10/05/15
Cross Section Design Fall 2009 Cross Section Design Lane Wldth Side Slopes Shoulders Curbs Traffic Barriers Cross Section Elements 0 Important Definitions Roadway The portion of a highway including shoulders for vehicular use For instance a divided highway has two or more roadways Traveled Way The portion of the roadway used for the movement of vehicles exclusive of shoulders Components of Cross Section Additiunul mw A AAk Desiml u Minimum ww gt 1 15 Rctluirud V TICfar 30mquot L lcar Zone Mammal R Wr K S er K githA F E d k 11H Shuuldtr Shuulder I PilVL mL 39lw l i i l Traveled Way Components of Cross Section Additiunul mw A AAk Desimhfu Minimum ww 1 15 Requirud Clamquot ZUHLquot Clear Z m Additional R Wr quot H X asquot quotx 739 K bud F I d kaHRequirud Shuuldtr Eilrmuldm I Puvumcmw H W i l 4 Roadway Components of Cross Section Additional RJ W AA Desirable Minimum WW 1 15 Required V Clear 20m Clear Zone Mdmuml KIWI z 1 S 1 qlW W Y F I d 39 115 l Shoulder Eilzwulder I riPuvemenl I l i l Rightof Way land owned by a government entity for public use state local etc Components of Cross Section Audimmal mm 15 Required Clear Zone Clear Zone Slmulder39 I L Shoulder I PilVL39lTlL Il39l m ii 1 Additional RJ W AA Deaimhle Minimum WW r 15 Required l Clear Zone Area located between the edgeof travel way and the location of fixed objects trees posts etc Components of Cross Section Additiunul mw A AAk Desimhfu Minimum ww 1 15 Requirud Clamquot ZUHLquot Clear Z m Additional R Wr quot H X asquot quotx 739 K bud F I d kaHRequirud Shuuldtr Eilrmuldm I Puvumcmw H W i l 4 Undivided Highways Components of Cross Section ROW FLO W L EUIIII 250 it i 7 l I L 4fquot5039Flf52 i in39j39i imwiflili 493m W I 13 Typical Divided Highways Components of Cross Section HUJN 39 I nulw Elm E llquot 39d gt I l l 4Hquot 5H39 1H P ELIquot I fjiil39 l39rl39lil39 I 3439 HIquotI 4I39J39 SUV a 1 a hair A 7 A L if I l 7 l lr rs r l l r I I I l l I MI m may 3 M v h 39I39ypicz Median Note Median measured from edgeof travel way to edgeof travel way Lane Width Range 9 ft to 12 ft 12 ft most commonly used on rural and urban highways adequate for most of the heavy vehicle 11 ft acceptable in urban areas to accommodate pedestrians crosswalk 10 ft acceptable on lowspeed highways 9 ft acceptable on local rural or urban streets residential Cross Slope Undivided highways tangent crown in the middle and a cross slope downward toward both edges Downward cross slope can be either a plane or a rounded section or both Rounded sections are usually parabolic Advantage cross slope steepens toward edges Disadvantage difficult to construct cross slope may be excessive in outer lanes Cross Slope Divided Highways each oneway traveled way can be crowned separately or can be unidirectional cross slope across the entire traveled way Crowned roadways have the advantages of rapidly drain water during rainstorms However need to install additional inlets and underground drainage lines Preferred in region of high rainfalls Cross Slope Crowned for Each Direction Cross Slope Unidirectional Cross Slope Cross Slope Unidirectional cross slope provide more comfort to drivers when they change lanes Drainage away from median may effect savings in drainage structures minimize drainage the inner highspeed lanes Drainage toward the median will increase costs but will minimize water on most used lanes of highways Cross Slope The rate of cross slope is an important element in crosssection design Towlane Highway 15 to 2 percent is acceptable drivers will have difficulty perceiving this rate 0 For three or more lanes start at 05 percent and increase by about 05 to 1 percent for each successive pair of lanes Cross Slope IE Cross Slope Steeper Cross Slope Cross slope steeper than 2 percent for high speed highways high type pavement with a central crowned design should be avoided Abrupt change in centrifugal force Trucks may sway high center of gravity Exception 25 in areas of intense rainfall Three or more lanes in each direction 4 max in areas of intense rainfall For cases where maximum cross slope is used consideration should be given for grooving and opengraded mixes Shoulders The shoulder is the portion of the roadway contiguous with the traveled way that accommodates stopped vehicles emergency use and lateral support of subbase base and surface courses 0 It can vary from 2 ft to 12 ft 0 Two types Graded width measured from edge of traveled way to intersection of the shoulder slope Usable width actual width that can be used when a driver makes an emergency stop Shoulders Ended Shaman gtAa p unlim Should if i Houndln 55 k 39 Ul bli 39 thn39u ld u Hg Exhibit 45 Graded and Usable Shnulders Shoulders Shoulders may be surfaced either full or partial width to provide a better allweather load support than that afforded by native soils Materials for shoulders gravel shell crushed rock mineral and chemical additive concrete and asphalt pavements Shoulders on minor roads serves essentially as structural support Narrow lane width narrow shoulders are usually associated with higher number of crashes Shoulders Advantages of welldesigned shoulders rural and urban highways freeways Space provided for vehicles in the event of an emergency Space for motorist to stop occasionally to consult road maps or for other reasons although illegal in many states Provide space for evasive maneuvers Structural support for pavement Space for pedestrians and cyclists in urban areas Shoulders Width of shoulders Desirably provide 1 ft to 2 ft between edge of traveled way and vehicle 2 ft low volume to 12 ft high speedhigh flow Wider may encourage unauthorized use of shoulder Shoulders should be continuous Might want to provide wider shoulders every mile or kilometer on elevated structures Shoulders Shoulder cross section Shoulder and traveled way must be jointly connected Cross Slope o Asphaltconcrete 2 to 6 percent 0 Gravel 4 to 6 percent 0 Turf 6 to 8 percent Avoid severe cross section break on horizontal CUI VES Desirable to use different color and texture between shoulders and traveled way night inclement weather etc Curbs Curbs are used for Drainage control Roadway edge delineation Rightof way reduction Delineation of pedestrian walkways They are mainly used on lowspeed roads 0 They should be avoided on highspeed highways mommaquot 3m 56m u mam quot1 Curbs momma quot r ommmsh H mum cuwss aw mumquot 7quot 1m m 551 V Curbs isomism rmmm sln 39 t 1 Curbs defined by vertical and WTquot x wmmwm horizontal configuration Elm iwmmiuni nmm ms Main mm HH 7 lawn mm H 2 um um ll55in sin T39 39 Kan15M 1M RBomn i m 39 m u M mom gum La 11 7 1mm mi 7 IN n m m M quotI W 215w iiiquot 2 11m in c g In immu 2quot m1 accum unmm in uquot scum mm gm 1 39li qm mm LL Hi i m j r vimquot 4 7a 2 Cu rbs 6 to 8 in Re ll lumm r MT Vertical curb Prevent from vehicles to leave th oadway I 39A E sh uld not be used on highspeed VERWLCW lg ways May be used along walls i 1 mm liv 39sllmmgm n I 3974 1 quot tunnels aim 713quot 39 mm quot quot FEW wagerquot an quotm n E m M W Elfal quot If we 1ng RIEDmm m WET 5 Curbs Horizontal sloping curb b if mi xlum H Mountable by vehicles 1 ll391 m quot quoti Rounded edge allow ease to be milA mountable during emergency mum Will scrap undersides of on Wm WM vehicles film quotlm imvmwlmh slim 374 m 39 Wi J quotlg73951quot WW rm aim an quotwa i39v 3m H in m um m1 j39JJ 39 F Ii Vimquot Curbs b gjpwm j M Limummsrm mm r Inf 5 In Horizontal extruded curb Mountable by vehicles Design to be mountable A mm m mum quot271 mm m twin waitng 7 Mn 7 How 2m Hm 21372 an quotMM n H MM 1 394 Wquot i J 1 15 2 W Curbs Gutters 1ftto6ftwide 5 to 8 percent grade limited to 2 3 ft adjacent to the curb Place gutters with proper spacing to prevent overflowing Use bicycle safe grates wherever bicycles are permitted Slideslopes Sideslopes are the area adjacent to the roadway used for drainage purposes 0 They are also used to ensure roadway stability and allow for recovery for an errant vehicle 0 Elements of sideslopes Hinge point Foreslope Ditch bottom Backslope Slideslopes DHMGE Palm E FUFIESLDF39E r 13 ancrstE Hm I3 I31 TEH BEITTIEJH T HHF FI E F LANE TRAFFIC 39ef HILFIEIJJE SHEULDER Lj l l h r TCIE r3 SLEIP E Exhibit 44 Designatiml If Rt adside Regions Slideslopes 7 iILiHlNGE PUIHT FUFI ESLDPE 1E BnCEELUFE El m TEH Horrori anFF 39quot smwnlst WW4 TUE or SLEIPE Exhibit all139 Designation of Roadside Regions May contribute to loss of steering control vehicle become airborne possibility of rollover Slideslopes e mHINGE Palm Er FUFIESLDPE lag BHCEELUFE anFEJ E EHHJLJLDER mmng H H TCIE Us SLEIF39E Exhibit all7 1 asilgnatiun If Rundside Regions Area where the driver can try to recover for lossof control vehicle Slideslopes 7 lithium PUIHT FUFI ESLDPE 1E BnCEELI JFE h THAFFIE EH ULDER TUE BF SLUPE Exhibit 41 es39gnati n nf nadside Regions The area where the vehicle will most likely end up if the driver cannot regain control of vehicle Slideslopes 7 EJHMEE PUIHIT FUFI ESLDPE lag BnCK ELUFE N THFIF FI C V LANE IHAFEJL EMULDER El m TEH anTmra fTDE BF SLEIF39E lati n If Rnadside Regions Exhibit 47 Desi Need to design the transition between foreslope and backslope adequately to prevent the vehicle to come to an abrupt stop Slideslopes Foreslopes should not be steeper than 1V3H general rule flatter the better but more costly If foreslope is steeper than 1V3H need to shield the slope with a guardrail or barrier Same kind of rules apply for backslope Need to ensure that transition points are rounded Be aware that different material used on foreslopes turf soil etc can have a different effects on the probability of a rollover known as tripping mechanisms Barriers Barriers are used for shielding hazardous to prevent vehicles leaving the traveled way to hit to an object that has a greater severity potential than the barrier itself 0 They should be used carefully since they are a source of crash potential themselves 0 There is a lot of research performed on barriers Thus you should be aware of the latest development on this topic Barriers Traffic barriers include two components Longitudinal barriers the primary function is to redirect errant vehicles Crash cushions the primary function is to decelerate errant vehicles 0 Two types of barriers Flexible allows for deflection cable guardrail Rigid no deflection is allowed concrete ROADSIDE BARRIERS Warrants for nontransferable terrain and objects 0mm unuga yum uhmmwu lmi mrhng umh ummm s m x rm dorms wan Duchm pancU mum Wmmw nnmmymm Ruhumng walk mm ugml wppum we Uulm mem Wan nut Jdmg gmum Mum mug dccisnm mm on mum oran amccr and nmnmnd or mva hr u w 1 mm 1 5mmquot not gummy rammed mm m r rum 3 s m m Smcmmg gcmum cqmmd F hkrhhond ofhmthm mpnul u th Judgman ducmnu mm on my lmghl mm slope we r warm 3 1 Judgmem daemon bmcd on ralmwe ymm hnms m Wu and unncvpdmrl mmmm ung t 0 1mer Mm ngah mum my Mum hn mv 7mm Am mghanwrl mml mmn u m mm ludgmcm dccmmv mm on summons cnunwm Shmldmg m1he Mmm on r cmmhvcmc bum mciumu urmcmncnmm ROADSIDE BARRIERS Example Design based on Speed Volume Slope Geometry AVERAGE ADT OVER DESlGN FERVOD lGu E ssh WARRANT LENGTH Hundreds ol Fee mum nu nanmslrv and lenmh m lnnA ms mmnmaw unllsl ROADSIDE BARRIERS Definition of roadside barriers LENIJTI 1 0 ram2 BRIDGE Int Lena39m or MZEEI i ETMLIAHI Tl clh TrlMI Fi39l nrII39MHI 7 7 I 55112 sruu q aITIrJN Ecnm m E 3quot TI IE JI J EHI rnE xTvah r 341qu 393 D V n I U D I 391 51 I LIL V l V r if HHLULL x EDGE C39F TI IH39UIA39IEquot DIRECTIUN 0F lFH J39ELED39 IWFAY I RN39JEL GUNBENT TI39I J39EI39HCI39I D FEC2TICI CIF TWOEL I CIPF GGINE THAIH5 F IGUHE 54 Definition of roadside harriErs MEDIAN BARRIERS Suggested Guidelines mm a WWW YHAer39n w gt my 7 7 1277 i mr ww Thuslt mm m y NEWMAN ARREERS M 4 u Ma V ThreeStand Cable MEDIAN BARRIERS BoxBeam Barrier MEDIAN BARRIERS Strong Post WBeam Frontage Roads Func ons Control access to the arterial Street facility serving adjoining properties Maintain circulation of traffic on each side of the arterial Cross connections provide access between traveled way and frontage roads and are located in the vicinity of the cross roads 0 Can be either oneway or twoway segments Frontage Roads ALLEbb Exhibit 4H ueway F mntage Rua s Entrance and Exit Ramps Frontage Roads Exhibit 4lL Twmway Frontage Builds Entrance and Exit Ramps Frontage Roads 0 Important characteristics Often create conflicts between accessibility and mobility Operating speed can become problematic In congested situations they can sometimes be used by drivers to skip congested area on main arterial often useless maneuver Can create congestion on local road system
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