mestrado integrado em engenharia civil mestrado em ... · engenharia de tráfego rodoviário / road...

Capa

city a

nd L

OS in

Rou

ndab

outs

Engenharia de Tráfego Rodoviário / Road Traffic Engineering MEC (Urbanismo, Transportes e Sistemas), MET, MPOT, MUOT 1

Mestrado Integrado em Engenharia Civil

Mestrado em Engenharia do Território

Disciplina: Engenharia de Tráfego Rodoviário

Prof. Responsável: Filipe Moura

Session 11: Capacity and LOS in Roundabouts

Methods

Capa

city a

nd L

OS in

Rou

ndab

outs

Estimation Models

 Statistical – Empirical

 Probabilistic - Gap acceptance

Geometry and traffic inputs

Capacity Empirical methods

Gap acceptance

Analytical methods

  Simulation Engenharia de Tráfego Rodoviário / Road Traffic Engineering MEC (Urbanismo, Transportes e Sistemas), MET, MPOT, MUOT 2

Capa

city a

nd L

OS in

Rou

ndab

outs

Methods

EMPIRICAL

  English (TRL)

  Portuguese

  French

  Swiss

  German

PROBABILISTIC

 NAASRA (National Association of Australian State Road Authorities)

 German


Capa

city a

nd L

OS in

Rou

ndab

outs

Determining the circulation flow

NN

EW

S

Circulation flow Or

Conflicting flow Entry Circulation flows

N S-W E-W E-S

W N-S E-S N-E

S N-E W-E W-N

E W-N S-N S-W


Capa

city a

nd L

OS in

Rou

ndab

outs

English and Portuguese Methods

Entry radius, r

Approach width, v

Entry width, e

Inscribed circle diameter, ICD

Entry angle, θ Effective length of flare, l’

Capacity is a function of six geometric parameters.


Capa

city a

nd L

OS in

Rou

ndab

outs

Computation of flare length

•  Entry flaring is localized widening at the point of entry. •  Normal Roundabouts usually have flared entries with the

addition of one or two lanes at the give way line to increase capacity. Single lane entries e.g. those at Compact Roundabouts, should be slightly flared to accommodate large goods vehicles. Even a small increase in entry width may increase capacity.

•  The average effective flare length, l', is the average length over which the entry widens. It is the length of the curve CF‘: •  AB = e (entry width). •  GH = v (approach half width at point G which is the best

estimate of the start of the flare). •  GD is parallel to AH and distance v from AH (v is measured

along a line perpendicular to both AH and GD and, therefore, the length of AD is only equal to v if AB is perpendicular to the median at A).

•  CF' is parallel to BG and distance ½ BD from the curve line BG

l’

A

B

H G

DC

F’


Capa

city a

nd L

OS in

Rou

ndab

outs

English method

)( cce QfFkQ ×−×=

!

k =1" 0,00347 # " 30( ) " 0,9781

r

$

% & '

( ) " 0,05

*

+ ,

-

. /

2303XF =

)2,01(210,0 2Xtf Dc +=

MtD +

+=15,01

−

=1060ICDexpM

SvevX212 +

−+= '

)(6,1

l

veS −=

 EFFICIENCY FACTOR

 MAX STOCKAGE Cap.

 CORRECTION Factor

 ACCUM. Potencial

WITH


Capa

city a

nd L

OS in

Rou

ndab

outs

Portuguese Method

)( cce QfFkQ ×−×=

−−−−= 05,0)1(431,3)30(00163,01r

k θ

247,335 XF =

)2,0457,0(611,0 2Xtf Dc +−=

MtD +

+=1983,01

 EFFICIENCY FACTOR

 MAX STOCKAGE Cap.

 CORRECTION Factor

 ACCUM. Potencial

−

=1060ICDexpM

SvevX212 +

−+= '

)(6,1

l

veS −=WITH


Capa

city a

nd L

OS in

Rou

ndab

outs

French Method

Entry width

Inscribed circle diameter

Exit width

Triangular island width

Circulatory roadway width

Capacity is function of 5 geometric parameters


Capa

city a

nd L

OS in

Rou

ndab

outs

French method

))5.3(1.01)(7.01330( −+×−= ENTQQ ce

Where

))8(085.01))(15/1(3/2( −−−+= ANNSEPQQQ stc

  Qc – Conflicting flow;

 Qs – exit flow (in the analysed approach);

 Qt – circulating flow (passes in front of the analysed approach);

 ENT – Entry width ;

 ANN – Circulatory roadway width;

 SEP – Triangular island width.


Capa

city a

nd L

OS in

Rou

ndab

outs

Swiss method

Capacity – function of 3 geometric parameters

Number of entry lanes

Number of lanes in the roundabout

Distance among conflicting points, b


Capa

city a

nd L

OS in

Rou

ndab

outs

Swiss method Ce =

1

!! (1500"

8

9Qg )

QD= !Qc +"Qs

  Ce – Entry capacity  QD – Disturbing flow   TCUe – Saturation flow at the entry   Qs – Exit flow;   Qc – Circulation flow (in the circulatory roadway);

Coefficients   α – influence of exit flow (depends on the distance between conflicting points)

  β – reduction factor   γ – flow distribution

Values of β (nº of lanes in the ring)

1 lane 2 lanes 3 lanes 0,9 – 1,0 0,6 - 0,8 0,5 – 0,6

%100..e

ee C

QTCU γ=

Values of γ (nº of entry lanes)

1 lane 2 lanes 3 lanes 1,0 0,6 - 0,7 0,5


Capa

city a

nd L

OS in

Rou

ndab

outs

German method

Number of entry lanes

Number of lanes

Capacity – function of two geometric parameters


Capa

city a

nd L

OS in

Rou

ndab

outs

German method

ce QQ ×−= 740,01218

ce QQ ×−= 532,01250

ce QQ ×−= 500,01380

ce QQ ×−= 420,01409

Number of lanes

Entry circulatory Capacity of entry

1 1

2 or 3

2 2

3


Capa

city a

nd L

OS in

Rou

ndab

outs

NAASRA method (Australian)

  fhve – Heavy vehicles adjustment factor;

  qc – conflicting flow (pcu/s);

  α – Critical Gap;

  β – Follow-up headway;

  Δc – intra-bunch headway (headway between vehicle circulating within the roundabout)

( ) ( )

β

α

c

cc

q

qccc

Hvec eeqqfQ

−

Δ−−

−

Δ−×=

113600

=

β3600

Hvef

0>cq

0=cq


Capa

city a

nd L

OS in

Rou

ndab

outs

German method of gap acceptance

( )cc

c

qn

c

ccHvec e

nqfQ Δ−−−×

×

Δ−×= βα

β5.036001

c

ccnqΔ

≤

c

cc

nqΔ

>

  fhve – Heavy vehicles adjustment factor;

  qc – conflicting flow - traffic volume on the circulatory roadway (pcu/s)

  Nc – Number of circulatory lanes (in roundabout)

  α – Critical Gap (=4.1sec.)

  β – Follow-up headway (=2.9sec.)

  Δc – intra-bunch headway - minimal time gap on the circulatory roadway

(=2.1sec.).


Capa

city a

nd L

OS in

Rou

ndab

outs

Case study - data

  ICD = 70 m

 Entry width = 7,0 m

  Lane width = 7,0 m

 Effective lenght of flare = ∞

  Island width = 3,5 m

 Diameter of the inner circle = 9,0 m

 Entry radius = 40 m

 Entru angle = 40º


Capa

city a

nd L

OS in

Rou

ndab

outs

Case study – results

0

500

1000

1500

2000

2500

3000

0 150 300 450 600 750 900 1050 1200 1350 1500 1650

Fluxos de Conflito (uvle/h)

Capa

cida

de d

a En

trada

(uvl

e/h)

Inglês Português Francês SuiçoAlemão AlemãoGap NAASRA

Lane

capa

city (

pc/hr

)

Conflict volume (pc/hr)


Capa

city a

nd L

OS in

Rou

ndab

outs

Other methods

  Ex-JAE

  HCM 2000

  Sidra (evolution of the australian method)


Capa

city a

nd L

OS in

Rou

ndab

outs

Comercial Software

ANALÍTICAL & EMPÍRICAL

  ARCADY

  RODEL

  aaSIDRA

  KREISEL

  GIRABASE

  HCS2000

SIMULATION

  CORSIM

  INTEGRATION

  SIMTRAFIC

  VISSIM

  PARAMICS


mestrado integrado em engenharia civil mestrado em ... · engenharia de tráfego rodoviário / road...

Documents