Horizontal Curves-Superelevation-And Geometric Design Standards

7/25/2019 Horizontal Curves-Superelevation-And Geometric Design Standards

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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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*easurement o/ "a2out constraint "c

Source : TD9/93 (DMRB)


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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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Horizontal Curves-Superelevation-And Geometric Design Standards

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