atms arterial

8/9/2019 ATMS Arterial

1/48

ATMS

Advanced Traffic Management Systems

Arterial Control Systems


2/48

ATMS

• Intent of ATMS:

– Improve operational control

– Adapt control strategies to current/expected

traffic

– Provide marginal improvements to system

capacity or throughput– Reduce congestion / delay / queues


3/48

ATMS Requires

• Control mechanism

• Surveillance function

• Communications

• Data manipulation

• Control algorithm• Maintenance function


4/48

Arterial ATMS – Traditional

Control

• Fixed timing plans assume

– Fixed volumes

– Fixed O/D patterns

• Traffic volumes are not constant – it!in an !our

– "et#een !ours

– From day to day


5/48

Arterial ATMS – Traditional

Control• $eople ad%ust t!eir traffic patterns

– &et#or' timing plans often use o(solete O/D

patterns

• Significant c!anges in timing plans are

disruptive to traffic flo#


6/48

Adaptive Control

• &et#or' timing plans are difficult to c!ange

significantly

– Traditional timing plan c!anges cause ma%or

disruptions in progression ) congestion


7/48

Arterial Solution – Adaptive

Control• Adaptive control*

– Small modifications to t!e current timing plan

to optimi+e ve!icle movements

– Dependent on surveillance inputs

– ,e-uires optimi+ation algorit!m


8/48

.xamples of TMS

• Arterials Control Systems– Actuated & semi-actuated control

– SCOOT– SCATS

– OPAC

– NSATMS– RT-TRACS

– RHODES


9/48

Arterial ATMS

• Simplistic version of adaptive control*

– Signal actuation

• Adaptive control (ecomes more difficult if

more significant c!anges are desired


10/48

SCOOT

• Split Cycle Offset Optimi+ation Tec!ni-ue

• "ritis!

• "asically on0line Transyt optimi+ation

• Ma'es only minor ad%ustments to t!e current plan


11/48

SCOOT

• 1ses upstream detector locations

– Must estimate -ueues / saturation

– "ut counts very #ell

• Optimi+es a performance index minimi+ing

– delays

– stops

– congestion


12/48

SCOOT

• Ad%usts

– cycle times

– p!ase times

– offsets

• Attempts to !old t!e most congested

intersection at 23 percent of saturation


13/48

SCATS

• Sydney Coordinated Adaptive TrafficSystem

• Australian

• Controls delay and stops – doesn4t actually

optimi+e


14/48

SCATS

• 5ierarc!ical su(system (ased

• Selects 6(est7 splits cycle offsets forcritical intersection #it!in eac! su(system (ased on measured saturation level t!en

• determines (est coordination plan for ot!ersu(system intersections


15/48

SCATS

• 1ses long 89:; m< stop (ar detectors

– "etter saturation measurement

– "etter -ueue measurement

– 5arder to compute volume

• Only incremental c!anges allo#ed eac!cycle


16/48

SCATS

• Su(systems are lin'ed #!en (ot! !ave t!e

same optimum cycle lengt!

• Su(system lengt!s can (e (ro'en if no

(enefits are present


17/48

O$AC

• Optimi+ation $olicies for Adaptive Control

• =solated intersection program 8sinceexpanded<

• 1ses a simplified dynamic programmingapproac! to optimi+e a performance value8delay<


18/48

O$AC

• 1ses advanced detectors 8li'e SCOOT<

• $redicts flo#s 8arrival time and total

volume< (ased on previous time periods

• Allo#s c!anges in cycle p!asing etc:


19/48

&SATMS 8as designed<

• Does not actually ad%ust timing plans

• Tells neig!(oring %urisdictions #!at is

!appening up0 or do#n0stream from t!em

• Allo#s operations personnel to select t!e

proper response


20/48

&SATMS

• >oal is to en!ance local control

• =ntent is to continue to use existing signal

control !ard#are / soft#are

– ?o#ers initial cost

– Allo#s 6coordination7 of independent net#or's


21/48

&SATMS

• ?imitation is t!at existing competing

vendor !ard#are #on4t tal' to eac! ot!er

• &eeds 6translator7 protocol

• =n future &CT=$ protocol


22/48

CurrentSignal

5ard#are

Translator

$rogram &SATMS

Future

Signal

5ard#are

&SATMS &TC=$ $rotocol

&TC=$

$rotocol

$roprietary

$rotocol

Current &SATMS Design

Future &SATMS Design


23/48

,5OD.S and ,T0T,ACS

• Modern signal control algorit!ms t!at

depend on more detailed sensor output


24/48

Arterial Control

• @ey -uestions are*

– !at data do you !ave

– !en do you !ave it

– !at control options do you !ave

– "ecause t!is determines t!e 'inds of analysisyou can do


25/48

"arriers

• Tec!nical

– ?ac' of communications

– ?ac' of surveillance

– Old underpo#ered proprietary infrastructure

– Cost

– ?ac' of personnel to operate / optimi+e controlalgorit!ms / strategies


26/48

"arriers

• Organi+ational / =nstitutional

– $olitical (arriers

– $roprietary !ard#are / soft#are from vendors

– !o controls t!e system

– Does t!e expertise exist to install operate and

maintain t!e system – Financial priorities


27/48

"arriers

• $olitical

– !at movements are optimi+ed

• Minimi+ed delay / stops not al#ays t!e prime goal

– ?ocal control versus 6regional7 control

– ?o# (id pu(lic contracts and vendor control

issues


28/48

"arriers

• Financial – Most agencies are 6poor7– Value of the system's benefits versus

– Cost of the system

• =nterconnect is expensive

• &e# 8capa(le< !ard#are is expensive• Must compete #it! ne# pavement and

re!a(ilitation


29/48

"arriers

• Training

– Staff 'no#ledge 8(ac'grounds<

• Communications

• Computing

• &et#or'ing

• Statistics

• Soft#are

– Staff ,etention


30/48

"arriers

• Consultant support

– Timing

– Cost

– ,elia(ility


31/48

=ntegration


32/48

!y =ntegration

• S!ared infrastructure can reduce costs

• Avoid duplication of infrastructure

• Allo#s 'no#ledge of conditions outside of

your control (oundaries

• =t increases t!e data/information availa(le

for operational controls


33/48

!at duplication

• .xamples*

– Toll tags – one tag for multiple toll roads

– Surveillance e-uipment

– Communications – T#o different in0ve!iclecomponents can s!are one off0ve!icle

communication system


34/48

=ntegration

Component integration

Bersus

System integration

8Similar (ut different<


35/48

Control System =ntegration

• T#o important aspects of integration

– Tec!nical integration

– Administrative integration


36/48

Tec!nical =ntegration

• Allo#ing independent components to #or'

toget!er*

– .:g: Stereo system components

• 5ard#are connections

• Soft#are connection


37/48


• "iggest issue is standardi+ation

– &e# tec!nology

– .xisting tec!nology

• &ational Arc!itecture

– $!ysical layer

– ?ogical ?ayer


38/48


• $!ysical layer

– Standardi+ed !ard#are connections• $lugs

• Ca(les

• Communication inputs


39/48


• Soft#are

– Data transfer protocols

– Transfer speed

– Data transmitted

• Content• Format

• 1nits


40/48

Administrative =ntegration

=ssues

• Do = really #ant to s!are #it! 6t!em7

• !o pays for #!at

• !o is responsi(le for #!at


41/48


• !at type of integration

– S!ared control

– S!ared data

– S!ared infrastructure

• Communications

• S!ared components 8tags<

• T!is drives #illingness to participate


42/48


Decision is (ased on (enefits versus cost


43/48

Administrative =ntegration 0

=ssues• Do = #ant to

– !at do = get

– 5o# muc! does it cost – !at control do = !ave

• =s my system dependent on someone else

• =s my system effected (y t!eirs

– $rivacy• System operator

• 1ser


44/48


• "enefits

– >ood #ill

– Cost reduction

– &e# data

– &e# capa(ilities

– 5appier user


45/48


• Costs

– .xtra infrastructure

– Added functionality may lead to less t!an

optimum component features for your original purpose

– $urc!asing limitations

– Added complexity to t!e original system – ?oss of control

– Customer reaction


46/48


• Control

– T!e more critical to your goal t!e less li'ely

you are to let ot!ers control t!e system

– ,elia(ility

– ,esponse time to pro(lems – Control decisions

– Cost versus responsi(ility


47/48


• $rivacy

– 1ser information

– Company information

– Freedom of =nformation act

• Balue of data versus cost of data

• Does access to data limit participation


48/48


Agencies agree to integration #!en

– T!ey see more (enefit t!an cost

– !en t!e cost is #it!in t!eir availa(le (udget

atms arterial

Documents