horizontal curves-superelevation-and geometric design standards
TRANSCRIPT
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Session 5: Horizontal Curves,Superelevation and Geometric
Design Standards
Session 5: Horizontal Curves,
Superelevation and Geometric
Design Standards
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HIGHWAY EGIEE!IG A
"E#E" 5
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"EA!IG $%&EC'I#ES
Part A: Horizontal Curves
Part B: Superelevation
Part C: Geometric Design Standards
Coursework
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S'!(C'(!E
Horizontal Curves
1!minute "reak
Superelevation
Geometric Design Standards
Coursework
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H$!I)$'A" A"IG*E' DESIG
#"$ective
%atc& t&e p&'sical elements o( t&e road to t&e needs o( t&e
driver and t&e ve&icle)
*&at are P&'sical elements o( t&e road+
! Curvature
! Gradient
! Cross(all , Cam"er- superelevation
! .unctions! /isi"ilit'
*&at are Driver and /e&icle needs+
, Speed- Sa(et'- #perational e((icienc'- no dela'-
%anoeuvra"ilit' 4
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Horizontal Alignment +cont-
0&ings to consider:
Sa(et'! visi"ilit' (or stopping and overtaking
#peration , relate alignment to t&e design speed o( t&eroad
conom'! value (or mone' "' making designs e((icient
nvironment! minimize environmental impact
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Horizontal Alignment
Straig&ts and Curves
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2
A
IP1
B
IP2
1
T1
T2
T3
T4
R1
R2
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Some .asic terms
Cross(all and 2ongitudinal (all
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%asic terms +cont-
CA%B3 A4D S5P32/A06#4
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%asic terms +Cont-
AD/3S CA%B3 #3 4GA06/ CA%B3
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'ra//ic 0lo1 'erms
Annual 0lo1! 0otal (low 7in "ot& directions8 on a road in
a 'ear)
Annual Average Dail2 'ra//ic +AAD'-! Annual 9low
divided "' ;< , t&e num"er o( da's in a 'ear) Basis (or
selection o( new road widt&=t'pe and pavement design)
Annual Average Hourl2 'ra//ic +AAH'-! Annual
Average Dail' 0ra((ic divided "' >? , t&e num"er o(
&ours in a da' ) i)e) AAH0 @ AAD0=>?
3ea4 Hour 0lo1s +3H0s- !0&eoretical maimum (low
occurring on t&e road at some time during t&e 'ear ,t'picall' during t&e rus& &ours
Classi/ied tra//ic counts, tra((ic count split into ve&icle
categories)
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Circular Curves
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4#0
0wo straig&ts and circular arc
De(lection angle )
0angents and 0angent distance
Circle properties
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Circular Curve 3arameters
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Deflection,
Tangent engt! o" Tangent #i$tance % Di$tance T1I
engt! of &'"(e % engt! along t!e a"c T1T2)
ong c!o"# % $t"aig!t #i$tance T1T2
Ra#i'$ of c'"(e* Ra#i'$ of ci"cle of +!ic! t!e a"c T1T2 i$ a $egent-.T1 o" .T2/
T!"o'g! c!ainage* ea$'"e# f"o a"it"a" c!ainage e"o #ene#
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Circular Curve Calculations
0angent lengt& 016 or 0>6
016 @ 30an7=>8 i)e) t&e tangent o( &al( t&e angle)
*&o doesnt know &ow to calculate t&e tangent o( an angle+
2engt& o( curve 01 to 0>
Derived (rom
Hence
*&ere is in degrees
2engt& o( 2ong C&ord 010> and C&ainages
2engt& o( 2ong c&ord 010>
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E6amples
1)A !o"iontal c'"(e i$ #e$igne# +it! a "a#i'$ of 800) T!e
c'"(e !a$ a tangent lengt! of 150 an# t!e oint ofinte"$ection of t!e g"a#ient$ at a c!ainage of 250)Dete"ine t!e c!ainage of t!e $econ# tangent oint gi(ena #eection angle of 20 #eg"ee$)
>)T+o $t"aig!t !o"iontal $ection$ of a "oa# inte"$ect at aoint I +!ic! i$ 1040)480 f"o t!e eginning of t!e"o'te) T!e #eection angle -/ i$ 16 an# a "a#i'$ of 560i$ to e in$e"te#)
Dete"ine:
i) 0&e tangent distance
ii) 0&e lengt& o( t&e circular curve
iii) 0&e c&ainage o( t&e point o( curve 7start8 and point o( tangent
7end8
iv) 0&e lengt& o( t&e long c&ord 7distance "etween t&e (irst and
second tangent 14
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Designing t7e 7orizontal Alignment
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Calculating curve 3roperties
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Desira.le C7aracteristics o/ Horizontal Curves
;a
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S(3E!E"E#A'I$
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0orces on a ve7icle moving round a .end
#utward centri(ugal (orce
9rictional (orce developed "etween t&e road sur(ace and
t&e t're
0&e weig&t o( t&e ve&icle19
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!esulting Superelevation E8uation
tan 9 0 or
3eplacing t&e speed in m=s "' Em=& and using g@ F)1m=s>
0&e uation "ecomes:
e
*&ere :
/ @ speed in Em=&
3@ radius 7m8
e@ rate o( superelevation 7tan! angle o( slope8
9 or I@ Coe((icient o( (riction
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Superelevation +cont- (; 3ractice
De$ign i$ a$e# on 55 of cent"if'gal fo"cealance# f"iction, an# t!e "e$t $'e"ele(ation)
Hence and
=
C
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'2pical #alues o/ Superelevation
E"an "oa#$ % 0)05 -5/
R'"al Roa#$ % 0)07 -7/
;ini' fo" #"ainage % 0)02 -2/
;a
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E6ample o/ Calculation
Example
*&at is t&e minimum radius o( curvature on a rural road
wit& a design speed o( 1km=& given t&at t&e
superelevation s&ould not eceed JK+
3@
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Application o/ Superelevation
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Ais o( 3otation , Centre line or eit&er c&annels
Circular Curves , >= on Straig&t and 1= on Curve
0ransition Curves , *&oll' along t&e transition lengt&
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'ransition Curves +not covered-
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o"t! entioning eca'$e ci"c'la" c'"(e$ a"e an o(e"*
$ilication
A#(antage$:*cent"if'gal fo"ce inc"ea$e$ an# #ec"ea$e$ g"a#'all on ent"an# e
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DESIG S'ADA!DS 'D
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*ain 'a.le in 'D
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0actors A//ecting Design Speed
i Alignment constraint +Ac-, measures constraining e((ect o(
alignment! a L"end'M alignment will make it di((icult to ac&ieve
&ig&er speeds
Depends on Bendiness and /isi"ilit' on t&e road t&us:
Hingle ca""iage+a$ Ac 12 % JIHIK60 L 2BK45
D'al ca""iage+a$ Ac 6)6 L BK10
!e"e B en#ine$$ -K@/ % H' of #eection angle$#i(i#e# lengt! of "oa#)JIHI !a"onic ean (i$iilit -/
JIHI nK-1KJ1L1KJ2L1KJ3L M L 1KJn/ )
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0actors A//ecting Design Speed +cont-
ii) Layout Constraint (Lc) km/h
;ea$'"e$ eNect of "oa# c"o$$*$ection, (e"ge +i#t! an#t!e f"eF'enc of O'nction$ an# acce$$e$)
o+ Acce$$ n'e"ing 2 to 5 e" @; ;e#i' Acce$$ n'e"ing 6 to 8 e" @ ig! Acce$$ n'e"ing 9 to 12 e" @)
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0actors A//ecting Design Speed +cont-
*easurement o/ "a2out constraint "c
Source : TD9/93 (DMRB)
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0actors A//ecting Design Speed +cont-
iii. Mandatory speed limits*T!ei" '$e +it! o"e conne# alignent$ +ill "e$t"ict
$ee#$ elo+ t!o$e f"eel ac!ie(ale)
Source : TD9/93 (DMRB)
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Selection o/ Design Speed
4ew 3ural 3oads ! 5se t&e values o( t&e la'out constraint 2c
and Alignment Constraint Acto derive t&is (rom 9igure 1)
isting 3ural 3oads , Similar to 4ew 3ural 3oads "ut wit& Ac
measured over a minimum lengt& o( >km including t&e section
o( improvement)
5r"an roads ,selected in line wit& speed limit (or t&e road
using 0a"le >)
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Selection o/ Design Speed +cont-
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Design speed related parameters
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!"E ! #$%H" &$#"'CE# $#$*$L$"+Minimum si,ht distances re-uired depend on desi,n speed oroad
i) #"!00$%1T+o &oonent$ % Pe"cetion*Reaction #i$tance an#B"a@ing #i$tance
ii) !E2"'3$% a) 4 Components 5) 6sually a5out 7 "imes the#toppin, #i,ht &istance
iii) "62$% (at 8unctions)1 9isi5ility splays (Co9ered 6nder:unctions)
"ypically1; ran,es rom 7.4mto mto ?@m(or residential and
industrial roads)
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Designing a !oad Alignment
2ocate a route , series o( straig&ts and curves (or t&e centreline
Select a trial design speed
5se Design speed to select design parameters 70a"le 0DF=F8
Draw up a trial alignment
%easure Acand 2c (or eac& section o( t&e road s&owing signi(icant
c&anges over a minimum lengt& o( >km)
5se Ac and 2cto calculate new design speed
C&eck Design speed against initial c&oice! identi(' areas o( t&e
route w&ic& ma' "e relaed to ac&ieve savings
3e!calculate t&e Design speed i( c&anges in geometr' result and
start process again at appropriate step
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!ela6ations and Departures /rom standards
TD9K93 alie$ to t"'n@ "oa#$
&ontain$ #etail$ of "ela
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Summar2
Nou now &ave enoug& 6n(ormation (or Horizontal curves
5nderstand Superelevation
Can now use design speed to derive parameters (rom
standards
2ook at 3elaations and compare to 2ocal Standards
%ore in(ormation (or 'our coursework
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Course1or4 3art ?
Surve' in dwg 9ormat added to O!stream
Geotec&nical 6n(ormation and Site 6nvestigation 3eports
added)
0&ings 'ou need to know:, 3oad location ! Done
, Horizontal and vertical alignment design , Hal(!wa'
, .unction t'pes and la'out, Basic road in(rastructure
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Course1or4 3art ?
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Course1or4 3art ?
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