Toward a new generation of traffic control systems

1
Toward a new generation of traffic control systems

• Marco Zennaro
• Prof. Raja Sengupta

2
Outline

• Current traffic control systems development
  process
• A new development process
• Case study
• Wireless communication, distributed computing and
  traffic control systems
• Distribution problems
• Proposed solution
• Approach advantages

3
Todays traffic controllers

• Multiple control devices are currently in use
• 2070 controller
• General purpose computers
• Eagle 2001 (Motorola 68360 microprocessor, 25
  MHz, 4MB RAM)
• OS-9 operative system
• Operating as a special purpose devices
• Implement a standard set of rule of operations
• pre-defined rules that can be tuned
• It is difficult to operate these systems
  according to non-standard rules

4
Traffic control system development process

• The traffic control engineers develop a new
  traffic control system design
• The new design is given to a vendor to be
  implemented
• Problems
• What if there is no budget to contract an EE to
  develop the system?
• What if the system returned by the vendor does
  not behave as expected?
• Proposed approach
• ENABLE the traffic control engineers to implement
  the systems
• CLOSE the gap between design and implementation

?
5
Proposed approach

• Develop an integrated software suite that
  automatically translate the design into
  executable code
• TTCS Tools for the development of traffic
  control systems
• Design / Simulation environment abstract from the
  low level details
• Control logic can be expressed at high level (as
  a mathematical equation for example)
• Low level hw related (often platform specific)
  issues hidden from the control designer
• The controller logic design is automatically
  converted into executable code
• No need to hire electrical engineers to turn the
  design into low-level C code
• Potential advantages Cost reduction, reduction
  of level of expertise needed

6
TTCS Tools for the development of traffic
control system
Design tools
Executable code
Automatic compilation
pc104.exe
motorola.exe
Interface with Simulator
Interface with 2070
NTCIP
HW
Traffic Simulator
Interface with Control
2070
PC104
7
Design tool Simulink

• High level language for control design control
  laws can be expressed as a difference /
  differential equation
• Synchronous abstraction time is a sequence of
  instants
• Interconnected blocks declare the relation
  between their input and outputs

Source Yuwei Li, Wei-Bin Zhang, Summary of
requirements Los Angeles Transit Priority
System, UCBerkeley
8
Design tool Simulink

• The developed control system design is then
  AUTOMATICALLY converted into executable code for
  target architecture using RealTime Workshop.
• No need to worry about low-level hardware
  details
• No need to hire an expert for the implementation

9
Traffic Simulator / 2070 Interface

• In order to design a traffic control system is
  necessary to test the design in a simulated
  environment
• Software simulation (e.g. Paramics, Vissim,
  etc.)
• Hardware in the loop simulation (e.g. PATH
  arterial traffic/transit lab)
• Currently under development
• Interface with the PATH HIL system
• Interface with sw traffic simulator
• Interface with 2070s

10
Preliminary results

• Simulink 2 Traffic Simulation Interface
• Under development (currently in third beta)
• Socket based
• Interface with the traffic simulator used in the
  PATH traffic lab
• Simulink 2 2070 interface
• Design stage
• NTCIP based

Simulink (CONTROL) C(k) D(k-1) .
PATH traffic lab traffic simulator
TCP sockets
TCP sockets
S2TS
11
Traffic Controller implemented so far

• Implemented
• pre-timed 2 phases NEMA control
• pre-timed 4 phases NEMA control
• Semi-actuated control
• Currently implementing
• Coordinated pre-timed control
• LADOT ACTS
• Abu-Lebdehs Integrated Adaptive-Signal
  Dynamic-Speed Control

12
Case study 1 pre-timed NEMA ring

• cycle_timek timek mod cycle_length

? 2 cycle_timeK gt cycle_length phase_split
Phasek ?
? 4 otherwise
Source Signalized Intersections Information
Guide. Chapter 4 Traffic Design and
Illumination, USDOT FHWA-HRT-04-091
13
Case study 2 Semiactuated

• Semi-actuated intersection
• Minor road get a green only when actuated
• Green on both directions need to last at least
  min_green seconds

? Phase_ACTk stop_line_sensor_activatedk
Phasek ?
? Phase_NACTk NOT stop_line_sensor_activatedk
? 2 (Phasek-1 2) AND (Main_in_greenk lt min_green)
Phase_ACTk ?
? 4 otherwise
14
Todays traffic controllers

• Networked devices
• coordinate operations
• remote control
• National Transportation Communications for ITS
  protocol (NTCIP) set of standards
• Universal Traffic Data Format (UTDF)
• 2070 controller I/O communication ports and
  sensors (Ethernet, serial, etc)
• It is difficult to operate these distributed
  systems according to non-standard operation
  rules
• Distributed system are harder to program
  communication, heterogeneity, synchronization,
  etc issues

15
Case study LADOT ATCS approach

• In the mid-1990s LADOT recognized the
  difficulty to maintain and enhance the system
  because of the low-level programming language it
  required
• Centralized approach

Adaptive Traffic Control System
Source Yuwei Li, Wei-Bin Zhang, Summary of
requirements Los Angeles Transit Priority
System, UCBerkeley
16
Case study Southern Queensland (AU)

• Scenario
• Small town (20 signals)
• 400 Km away from the TMC
• Wired communication infrastructure too expensive
  (1,000/yrkm)
• Wireless (mesh) DSL (67 savings over initial
  and operational costs)

Source ITS International, March/April 2006 issue
17
Lesson learned

• Wireless is cheap and easy but
• Bandwidth is limited
• Higher data loss
• Distributed systems are harder to program
• Main gain was obtained adding
• Flexibility
• Upgradeability
• Examples
• Switching from dedicated communication networks
  (e.g. the one used in ACTS) to an open IP
  architecture
• Modular code (subsystem can be easily plugged-in
  / upgraded without impacting the rest of the
  system)

Source ITS International, March/April 2006 issue
18
Research question

• Can Simulink system be distributed over
  communication networks while preserving their
  semantic (i.e. behave as in simulation) and the
  modular structure (so that local changes can be
  handled locally)?

Embeeded System (2070)
Simulink
Control
Embeeded System (PC104)
Control (Executable code)
Interface with Simulator
Embeeded System (170)
Traffic Simulator
Interface with Control
Control (Executable code)
19
Answer

• NO
• No support for code distribution
• Compiled code is NOT modular!

Cycle length control
Phase split control
Offset control
2070 controller
dependencies
20
Compilation scheme problem

• Computations (read input, write outputs, internal
  computations) need to be carried sequentially
• The compiler fixes a computation order to avoid
  deadlocks
• Algorithm choosing any linearization of the I/O
  causality relation and execute computations in
  that order

Input 1
Output 1
Input 2
Output 2
21
Compilation scheme problem

• Computations (read input, write outputs, internal
  computations) need to be carried sequentially
• The compiler fixes a computation order to avoid
  deadlocks
• Algorithm choosing any linearization of the I/O
  causality relation and execute computations in
  that order

4
3
Input 1
Output 1
1
2
Input 2
Output 2
22
Compilation scheme problem

• Computations (read input, write outputs, internal
  computations) need to be carried sequentially
• The compiler fixes a computation order to avoid
  deadlocks
• Algorithm choosing any linearization of the I/O
  causality relation and execute computations in
  that order

4
3
Input 1
Output 1
1
2
Input 2
Output 2
23
Formal framework

• Step 1 Develop a formal framework where to
  investigate the question theoretically
• A modified version of the Synchronous Transition
  System1 (STS) formalism has been used to model
  Simulink
• Standard Reactive Automata2 (RA) formalism has
  been used to model the executable sequential
  code
• The semantic is given in terms of traces3
• 1 Manna, Pnueli, The temporal logic of
  reactive and concurrent systems, Springer-Verlag
  1992
• 2 Caillaud, Caspi, Girault, Jard, Distributing
  automata for asynchronous network of processors,
  European Journal on Automated Systems, 1997
• 3 Benveniste, Caillaud, Guernic,
  Compositionality in dataflow synchronous
  languages specification and distributed code
  generation. Information and Computation (2000)

24
First result

• We define the map ? from RA to FSTS traces as
  Benveniste3
• Implementation theorem given the map ? from RA
  to STS traces the implementation map ? has the
  following property for all STS s and RA r the
  following holds
• That is to say the RA r that implements the
  FSTS s has the same set of behaviors of s.
• 3 Benveniste, Caillaud, Guernic,
  Compositionality in dataflow synchronous
  languages specification and distributed code
  generation. Information and Computation (2000)
• 4 Zennaro, Sengupta, Distributing Synchronous
  Systems with Modular Structure, IEEE CSS
  Conference on Decision and Control, 2004
• 5 Zennaro, Sengupta, "Distributing Synchronous
  Programs Using Bounded Queues", 5th ACM
  International Conference on Embedded Software
  (EMSOFT), 2005

25
Second result

• Monomorphism ? is a monomorphism between (FSTS,
  xSTS) and (RA, xRA). The following must hold for
  all FSTS s1 and s2 and RA r1 and r2

4 Zennaro, Sengupta, Distributing Synchronous
Systems with Modular Structure, IEEE CSS
Conference on Decision and Control, 2004 5
Zennaro, Sengupta, "Distributing Synchronous
Programs Using Bounded Queues", 5th ACM
International Conference on Embedded Software
(EMSOFT), 2005
26
Second result

• That is to say
• Since xRA can be implemented across networks,
  since ? maps FSTS to RA with the same behavior,
  we can implement an FSTS as a distributed RA
  system
• Synchronous program can be implemented across
  networks taking full advantage of concurrency
  while preserving the synchronous semantic
• The implemented FSTS system maintain the modular
  structure of the original FSTS system Because of
  it changes can be handled locally

27
From theory to practice

• Step 2 Based upon this theoretical framework, we
  built a library to use with Simulink for the
  development of Modular Distributed Systems (MDS)
  library6

Source Zennaro, Sengupta, "Distributing
Synchronous Programs Using Bounded Queues", 5th
ACM International Conference on Embedded Software
(EMSOFT), 2005
28
Research question

• Can Simulink system be distributed over
  communication networks while preserving their
  semantic (i.e. behave as in simulation) and the
  modular structure (so that local changes can be
  handled locally)? YES

Embeeded System (2070)
Simulink
Control
Embeeded System (PC104)
Control (Executable code)
Interface with Simulator
Embeeded System (170)
Traffic Simulator
Interface with Control
Control (Executable code)
29
A more sustainable approach to traffic control
systems

• Developing countries are most affected by road
  traffic accidents
• The available budget is limited
• Experts availability may be limited
• The presented approach
• reduce the development / deployment /
  maintenance / upgrade costs
• reduce the required level of expertise
• Relying on
• Cheaper hw
• Appropriate sw environment

30
Computing platforms trend
31
Technology penetration

• Data source Telecom Regulatory Authority of India

32
Conclusion

• Modern traffic controllers are sophisticated
  general purpose computers that are hard to
  program for non standard operation rules
• The proposed software environment simplify the
  development of the system automatically
  converting the high level design into executable
  code
• Modern traffic controllers can be interconnected
  for remote or coordinate control. Again they are
  hard to program to follow non standard operation
  rules
• Wireless technologies can be used to reduce the
  system cost
• Simulink does not support distributed
  compilation
• The proposed compilation scheme allow distributed
  modular compilation of Simulink systems
• The cost and level of expertise reduction makes
  the technology more accessible

33
Questions?

• Software download
• TTCS http//ttcs.zennaro.net
• Related publications
• Zennaro, Sengupta, Modular Composition of
  Synchronous Programs Applications to Traffic
  Signal Control, submitted to ACM Transaction on
  Embedded Computing Systems.
• Zennaro, Sengupta, Distributing Synchronous
  Programs Using Bounded Queues, a coordinated
  traffic signal application, University of
  California at Berkeley, Intelligent
  Transportation Studies, UCB-ITS-RR-2005-4, May
  2005
• Zennaro, Sengupta, Distributing Synchronous
  Programs Using Bounded Queues , 5th ACM
  International Conference on Embedded Software
  (EMSOFT'05), December 2005
• Zennaro, Sengupta, Distributing Synchronous
  Systems with Modular Structure, IEEE 2004 44th
  Conference on Decision and Control, December 2004

34
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35
Extra slides

• Just in case

36
Western solutions

• Increasing system complexity
• single traffic light operating according to
  pre-timed plans
• actuated system able to sense and respond to
  traffic conditions
• coordinated intercommunicating traffic lights
  along an arterial
• systems able to accommodate different traffic
  priorities.

37
Previous experiences lesson learned

• Previous experiences
• Computers
• Computer networks
• Telephones
• Similar trends
• Started as
• expensive solutions
• shared by elite experts
• To became
• affordable mass gadgets
• Used everywhere around the world (120 mil cells
  in India)
• What made this possible?

38
ENIAC
Operators / Device
Intel 4004
ENIAC (1946) Cost 500,000
Apple II
Lotus 123
IBM 5150
Apple Newton
IPOD
Mainframe (costly, tens of operators per machine)
Minicomputer (less costly, ten operators per
machine)
Microcomputer (affordable, few operators per
machine)
Personal computer (affordable, one operator per
machine)
PDAs, (many machines per person)
time
1946
today
1970
39
Apple 2 (1977) Cost 1298
ENIAC
Operators / Device
Intel 4004
Intel 4040 (1971) Cost 1000
Apple II
Lotus 123
IBM 5150
Apple Newton
IPOD
Mainframe (costly, tens of operators per machine)
Minicomputer (less costly, ten operators per
machine)
Microcomputer (affordable, few operators per
machine)
Personal computer (affordable, one operator per
machine)
PDAs, (many machines per person)
time
1946
today
1970
40
ENIAC
Operators / Device
Intel 4004
IMB 5150 (1981) Cost 1,565
Apple II
Lotus 123
IBM 5150
Apple Newton
IPOD
Mainframe (costly, tens of operators per machine)
Minicomputer (less costly, ten operators per
machine)
Microcomputer (affordable, few operators per
machine)
Personal computer (affordable, one operator per
machine)
PDAs, (many machines per person)
time
1946
today
1970
41
ENIAC
Apple IPOD (2001) Cost 299
Operators / Device
Intel 4004
Apple Newton (1993) Cost 1000
Apple II
Lotus 123
IBM 5150
Apple Newton
IPOD
Mainframe (costly, tens of operators per machine)
Minicomputer (less costly, ten operators per
machine)
Microcomputer (affordable, few operators per
machine)
Personal computer (affordable, one operator per
machine)
PDAs, (many machines per person)
time
1946
today
1970
42
Outline

• Problem statement
• Lesson learned from similar experiences
• Case study Southern Queensland Traffic Control
  System
• Proposed approach
• Achievements
• Current and future work

43
What made this possible?

• System life-cycle
• Cost reduction in the initial investment
• ENIAC 500,000
• PC lt1,000
• Simplified deployment
• ENIAC team of scientist
• PC single operator (undergrad)
• Simplified maintenance
• ENIAC team of scientist
• PC automatic / single admin can monitor multiple
  systems
• Simplified upgrade
• ENIAC system shutdown
• PC plug-and-play

44
Research problem

• This is due to the existing gap between
• Simulation environment
• Used during the design phase
• Must hide implementation details, traffic control
  designer should not be concerned of low level
  hardware details
• Implementation environment
• Used in the development phase
• Need to address low level details
• GOAL close the gap between design and
  implementation

45
Road Traffic Injury Problem

• Problem size
• 1.2 million death worldwide
• 20 million injured people
• Disparity between high-income country and the
  rest of the world
• Less than 130,000 fatalities in high income
  country
• Second cause of death on the 5 to 29 y.o.
  population in low and middle income country
• Car accident ranks 8th in the global burden of
  disease and injuries (DALYs scale)

Source Pedan et all, The injury Chart Book,
WHO, Geneva 2002
46
Transportation Trend
Data source http//www.photius.com
47
Accidents trend
Source A. Sarna, Improving Road Safety in
Developing Countries Workshop presentation, 2006
48
Road Traffic Injury Problem
Source Mathers et al. Updated projections of
Global mortality and Burden of Disease, WHO 2005
49
Traffic control system design process

1. The traffic control engineers develop a new
   traffic control system design

50
Traffic control system design process

1. The traffic control engineers develop a new
   traffic control system design
2. The new design is given to a vendor to be
   implemented

51
Traffic control system design process

• The traffic control engineers develop a new
  traffic control system design
• The new design is given to a vendor to be
  implemented
• Problems
• What if there is no budget to contract an EE to
  develop the system?
• What if the system returned by the vendor does
  not behave as expected?
• Proposed approach
• ENABLE the traffic control engineers to implement
  the systems
• CLOSE the gap between design and implementation

?
52
The vision
Simulink
Embeeded System (2070)
Control
RT Workshop Our libraries
Embeeded System (PC104)
Control (Executable code)
Simulated system
Control (Executable code)
Embeeded System (170)

• Use the same development process to design the
  control code and compile into code to be executed
  on the traffic controllers.

Control (Executable code)
53
Achievements
vk
uk
wk
vk uk
wk vk
v00 v11 v32
w00 w11 w32
u00 u11 u32
?
?
?u(su)
?v(sv)
?
swsv !w(sw)
svsu !v(sv)

• We implement synchronous subsystems as
  asynchronous reactive automata with an equivalent
  behavior
• We compose automata using rendezvous composition
  and we prove that every behavior of the resulting
  system can be mapped to a behavior of the
  original system

54
Achievements
vk
wk
uk
wk vkzk
vk 2 uk
u00 w00 u11 w14 u22 w28
zk
zk 2 uk
?
?z(sz)
?v(sv)
?u(su)
?u(su)
?v(sv)
?z(sz)
?
?
sz2su !z(sz)
sv2su !v(sv)
swszsv!w(sw)

• The proposed approach take full advantage of
  
  concurrency while hiding the complexity of the
  
  interleaving from the user
• We proved that the proposed approach maps
  causal-loop free synchronous systems into
  dead-lock free asynchronous systems

55
Achievements
vk
wk
uk
wk vkzk
vk 2 uk
u00 w00 u11 w14 u22 w28
zk
zk 2 uk
?
?z(sz)
?v(sv)
?u(su)
?u(su)
?v(sv)
?z(sz)
?
?
sz2su !z(sz)
sv2su !v(sv)
swszsv!w(sw)

• A local change requires only local re-compilation
  (i.e. the modularity of the synchronous system is
  preserved in its asynchronous equivalent)

56
Achievements
vk
wk
uk
wk vkzk
vk 2 uk
u00 w00 u11 w14 u22 w28
zk
zk 3 uk
?
?z(sz)
?v(sv)
?u(su)
?u(su)
?v(sv)
?z(sz)
?
?
sz3su !z(sz)
sv2su !v(sv)
swszsv!w(sw)

• Local change requires only local re-compilation
  (i.e. the modularity of the synchronous system is
  preserved in its asynchronous equivalent)

57
Case study ASDS control system

• Step 3 Implement some simple traffic control
  system as a proof of concepts
• Adaptive-Signal Dynamic Speed Control
• GOAL minimize delay and number of stops
• IDEA
• treat speed as a control variable
• drivers choice is link optimal while ASDS can
  select a system-optimal speed
• Source Abu-Lebdeh, Integrated Adaptive-Signal
  Dynamic-Speed Control of Signalized Arterials",
  5th ACM International Conference on Embedded
  Software (EMSOFT), 2005

58
Case study ASDS control system

• The alternative control scheme was developed
  using Simulink and run over wirelessly connected
  laptops

59
Case study 1 Paramics
60
Case study Simulink
61
Case study 2 Paramics
62
Case study 3 Paramics
63
Case study 3 Simulink
64
Case study 3 Simulink
65
ENIAC
Apple IPOD (2001) Cost 299
Operators / Device
Intel 4004
ENIAC (1946) Cost 500,000
Apple II
Lotus 123
IBM 5150
Apple Newton
IPOD
Mainframe (costly, tens of operators per machine)
Minicomputer (less costly, ten operators per
machine)
Microcomputer (affordable, few operators per
machine)
Personal computer (affordable, one operator per
machine)
PDAs, (many machines per person)
time
1946
today
1970
66
Technology penetration

• Data source Telecom Regulatory Authority of India

67
Toward a sustainable approach to traffic control
systems

• Sustainable approach
• Abating the cost in each phase of the system life
  cycle
• Leveraging on embedded computing and wireless
  technologies (cost reduction)
• Abating the level of expertise required to
  develop / deploy / maintain the system
  (simplification)
• Leveraging on suitable software environments

68
TTCS Tools for the development of traffic
control system
Design tools
Executable code
Automatic compilation
1.exe
2.exe
Interface with Simulator
Interface with 2070
NTCIP
HW
Traffic Simulator
Interface with Control
2070
PC104
69
Case study 2 Utah intersection

• Multi lane intersection (somewhere, Utah)
• Pre-timed 4-phases NEMA ring