TR9302-CS 910506Barton-Aschman Associates, Inc.
5485 Belt Line Road, Suite 199 Phone: (214) 991-1900
Dallas, Texas 75240 Fax: (214) 490-9261
USA Metro: 263-9138
May 6, 1991
Ms. M. Shohre Daneshmand, P.E.
Acting City Engineer
City of Coppell
P.O. Box 478
Coppell, TX 75019
Dear Shohre:
Barton-Aschman Associates, Inc. would like to thank you for the opportunity to share
information about our firm and to discuss the SDHPT's Traffic Light Synchronization (TLS)
program. As I stated, the TLS program is a program administered by the SDHPT for the
optimization of traffic signal timing plans and the replacement and/or installation of equipment
necessary for the implementation of signal systems.
Enclosed for your information is a descriptive summary of the TLS program (Exhibit A).
Additional information and grant applications are available from your local SDHPT district
office. July 26, 1991 is the deadline for SDHPT receipt of grant applications. I would
encourage you to contact your local SDHPT district as soon as possible if you are interested
in this program.
The Dallas office of Barton-Aschman has taken the lead among Texas consultants in the State
sponsored TLS program. Our office is directing the activity of ten (10) signal retiming projects
around the State. Phase 1 TLS projects include the cities of Dallas, Duncanville, Fort Worth,
Garland and Hurst. Phase 2 TLS projects include the cities of Addison, Brownwood,
Corsicana, Mineral Wells and San Angelo. The number of study locations for these projects
range from eight (8) to eighty-four (84) signalized intersections. In addition to the ten (10)
TLS projects, Barton-Aschman is also providing consulting services to the cities of College
Station, Fort Worth, and North Richland Hills under a similar State program, the Traffic
Management (TM) program. Exhibit B summarizes Barton-Aschman's current TLS and TM
projects.
We are encouraged that the City of Coppell is considering closed loop signal systems. For
your information I have enclosed a copy of a paper (Exhibit C) entitled "An Overview and
Listing of Closed Loop Signal Systems for NEMA-Type Controllers". This paper was published
in the ITE 1988 Compendium of Technical Papers and was written by one of our Dallas office
staff members. This paper will give you a brief introduction into the closed loop signal system
concept.
Barton-Aschman would welcome the opportunity to work with the City of Coppell regarding
the TLS program or any other traffic/transportation needs the City might have. We are
particularly well qualified to undertake any of the projects that fall within the scope of the TLS
program. We are also available to assist the City with the preparation and submission of the
Ms. M. Shohre Daneshmand, P.E.
May 6, 1991
Page 2
Again, we are most interested in assisting you with the TLS program. Please let me know if
you have any questions or need additional information.
Sincerely,
BARTON-ASCHM~AN ASSO.~S, INC.
Senior Associate
KRM:rmb
encl.
kr~d~ne~hma.Ggl 1
Ms. M. Shohre Daneshmand, P.E.
May 6, 1991
Page 3
EXHIBIT A
THE TRAFFIC LIGHT SYNCHRONIZATION PROGRAM
PROGRAM DESCRIPTION
The State Department of Highways and Public Transportation (SDHPT) has been officially
designated Supervising Agency for the second Traffic Light Synchronization (TLS II) program
by the Governor's Energy Management Center. This program, which will be funded with Oil
Overcharge funds, will provide to local city governments across the state the sum of $5
million for the optimization of traffic signal timing plans and the replacement of signal
systems. These funds will help traffic engineers reduce unnecessary vehicle stops and delays
through improved traffic signal timing. Significant fuel savings and a reduction in vehicle
emissions should also be realized.
The TLS funds will be expended through the SDHPT on projects proposed by local city
governments. Projects will be selected to help assure an equitable distribution of funds to
urban and rural areas of the state. There will be three major funding categories: large cities
(cities with populations over 200,000), medium-sized cities (cities with populations ranging
between 50,000 and 200,000), and small cities (cities with populations under 50,000).
Populations will be based on final 1990 Census Bureau figures. Funds will be distributed as
follows: 50 percent of available funds will be expended in large cities, with each of the eight
cities presently over 200,000 population eligible for an allotment proportional to its population
provided viable projects are submitted; the remaining 50% of available funds will be evenly
distributed (25% - 25%) between medium-sized cities and small cities. Projects submitted
by medium-sized cities and small cities will compete with each other for funds within their
respective categories and the total amount proposed for reimbursement within an individual
project in these two categories must not exceed $120,000. Funds will be moved from one
population category to another if they cannot be fully expended. Funding allotments for cities
over 200,000 population can be obtained from local SDHPT district offices.
Up to 75 percent of project costs are eligible for reimbursement. However, not more than
20% of reimbursable costs can be earmarked for equipment. If a project is funded, the local
government or the SDHPT must pay a minimum 25 percent of the total direct costs of the
project in matching funds and/or in-kind services. The SDHPT will provide a local match when
a project contains traffic signals that are maintained and operated by the SDHPT, unless the
local government and the SDHPT agree otherwise. However, the city must first obtain
approval of the proposed project from the local SDHPT district office. The SDHPT local match
will be proportional to project costs attributable to SDHPT traffic signals.
Costs eligible for reimbursement under the program include: (1) training local staff and/or
consultants in the use of computer technology for the retiming of traffic signals, (2) data
collection, (3) development and implementation of timing plans, (4) replacement and/or
installation of equipment necessary for the implementation of signal systems (modernization
of signal poles and mast arms are not eligible) and (5) preparation of "Before" and "After"
Ms. M. Shohre Daneshmand, P.E.
May 6, 1991
Page 4
studies.
TLS program funds shall not be used to supplant or replace existing funds earmarked for
specific signal projects. That is, if existing funds are authorized for signal expenditures, those
funds may not be released and then replaced by TLS funds.
The TLS program will target traffic control systems currently coordinated and controlled in a
manner that permits implementation of multiple timing plans (i.e., timing plans that match
traffic needs at different times of day). By focusing on traffic signal systems that currently
have coordination capabilities, maximum energy savings can be realized with the available
funds. However, isolated signals are also eligible under this program. Projects which propose
the installation of signals where none presently exist will not be eligible.
Additional information concerning the TLS program is included in the Grant Application Manual
which is available from local district offices.
SELECTION CRITERIA
Projects will be ranked and recommended for funding using the following criteria:
1. Operational Characteristics of the Traffic Signal System - operation characteristics such
as delay, average travel speed, average daily traffic, etc., will be considered to
determine the amount of benefit improved signal timing can produce.
2. Availability of Local Staff to Implement Timing Plans - having local staff available will
allow the knowledge gained through the technical training to be retained and
encourage future retiming efforts to be undertaken by local city governments.
3. Average Signal Spacing - the greater the concentration of signals, the more important
synchronization and optimal signal timing become. A signal must be no further than
one mile from an adjacent signal for it to be considered part of a signal system.
4. Other Criteria such as Recent Growth in the Project Area, Date of Last Retiming Effort,
Level of Expansion Over Current Effort, and Certification that TLS Funds will
Supplement and not Supplant Existing Funds - these criteria will aid in determining
where the need for Tis funds is greatest and where maximum benefit can be achieved.
Ms. M. Shohre Daneshmand, P.E.
May 6, 1991
Page 5
EXHIBIT B
TLS/TM PROJECT SUMMARIES
City Program/ Intersections System Total Key Contact
Phase Type Subsystems
Dallas TLS/1 84 Arterial/ 12 Beth Ramirez, P.E.
Grid (214) 670-3122
Duncanville TLS/1 8 Arterial I Steve Miller, P.E.
(214) 780-5015
Fort Worth TLS/1 33 Arterial 7 Scott Booker, P.E.
(817) 870-8775
Garland TLS/1 43 Arterial 6 Larry Cervenka, P.E.
(214) 205-2439
Hurst TLS/1 13 Arterial 2 Jim Sparks, P.E.
(817) 281-6160
Addison TLS/2 22 Arterial/ 4 Robin Jones
Grid (214) 450-2849
Brownvvood TLS/2 9 Grid 1 Don Hatcher, P.E.
(915) 646-6056
Corsicana TLS/2 14 Grid 1 Gary Anderson
(903) 872-4811
Mineral Wells TLS/2 8 Grid 1 Dennis Beach
(817) 328-1211
San Angelo TLS/2 39 Arterial/ 4 Don Abell
Grid (915) 657-4241
College TM 36 Arterial/ 7 Mark Schoenemann
Station Grid (409) 764-3450
Fort Worth TM 25 Isolated 0 Scott Booker, P.E.
(817) 870-8776
North TM 7 Arterial 1 John Johnston
Richland Hills (817) 581-5500
EXHIBIT C
An Overview and Listing of
Closed-Loop Signal Systems for NEMA-Type Controllers
Brian K. Shewski (A)
Traffic control systems have seen many changes over Due to the rapid technological advancements of closed
the past decade. These changes have paralleled advan- loop systems, each manufacturer's current literature
cements in microprocessor and communications tech- should be consulted for updated information.
nology as well as in personal computers and traffic
control software. The use of a personal computer is a CLOSED LOOP SYSTEM CONCEPTS
relatively recent offshoot of the earlier traffic
control systems. This system has indeed benefitted The development of the closed loop system concept has
from the aforementioned advancements in technology, given the traffic engineer the ability to monitor and
The generic name "closed loop", whose origins date in most cases control local intersections from a
back to the first traffic responsive signal systems, central location. Earlier traffic control systems
has found general acceptance when describing a traffic typically consisted of detectors, a system master, a
responsive, distributed traffic control system uti- system coordination unit and local controllers. This
lizing a personal computer. A closed loop system can system provided for only one way communication.
indeed utilize a personal computer to monitor and Traffic data was transmitted from the system master to
control the operations of local intersections through the local controller, but feedback from the local
the use of applicable computer software, two-way com- controller was not possible. The early systems had
munications, on-street system masters and local inter- several drawbacks, chief among these was the inability
section controllers, to monitor system operations.
The objectives of this paper are to briefly review the The inability to monitor system operations led to the
concept and components of the closed loop system and design of the first closed loop system. The loop
to present a listing of features for several current between the system master and local controller was
closed loop signal systems utilizing NEMA-type "closed" with the added capability of the local
controllers. This paper is not intended as an endor- controller to send system operating parameters and
sement of NEMA-type controllers over Model 170 diagnostic checks back to the system master which in
controllers, nor is it intended as an endorsement of turn could be monitored by a central computer.
~ny ~ardfacturer. A partial list of manufacturers
mentioned in this paper are listed below: Current technology has indeed "closed the loop" in
traffic control systems. In addition to monitoring
1. Eagle Signal Controls - MA~Ctm local intersections, the newer closed loop systems
Traffic Management and Control System (1) can control the operations of the signal system by
downloading operating parameters from a personal com-
2. Econolite Control Products, Inc. - KMC Master puter.
Monitor Multiple Arterial Management System (2)
Closed Loop System Advantages
3. Kentron, Inc. - 1700 PC Closed Loop System (3)
Most coordinated traffic control systems offer signi-
4. Minnesota Microtronics, Inc. (2M) - Minnesota ficant advantages. Some of the principal advantages
Microtronics Traffic Control System {4) of closed loop systems include:
5. Sonex - ZDC Closed Loop Distributed Traffic · Lower Computer Costs - A personal computer can be
Control System (5) bought at a fraction of the cost of centralized
mainframe or mi nico~uter.
6. Traconex, Inc. - TracoNetTM (6)
· System Operation Monitoring - This characteristic
7. Traffic Control Technologies (TCT) - LM100 Closed is one of the primary functions of the system.
Loop System (7) Traffic engineering staff can monitor the status
of any location within the system.
8. Transyt Corporation - 3800 Closed Loop System (8)
· ~stem Malfunction Diagnosis An important
9. Winko-Matic Signal Company (Multisonics Corpora- feature of a closed loop system is the ability to
tion) 0SAM 32TM Traffic Responsive On-Street rapidly diagnose signal conl~onent malfunctions.
Master (9) This leads to lesser down times for the signal
system which in turn reduces driver inconvenience
and confusion.
ITE 1988 Compendium of Technical Papers/135
m Centralized System Control - Through the use of a T~e 19S5 Traffic Control Systems Handbook (10),
personal computer, downloading of the system data Chapter I~ (Selection of A System) and Chapter 11
base and intersection timing plans can be facil- (]esign and implementation), offers a good overview
itated. This allows traffic engineering person- into the system selection process of a traffic control
riel the freedom from changing the signal timing system. ~ Few o~ the major topics discussed ir these
in the field, cha~ters are as follows:
· Flexibility in System Mode of Operation The !. Chapter 10
mode of operation can either by traffic respon- , Federal-AiO Requirements
sire (actuated), time-of-day (day-of-week} or m System Selection Process
manual operation among others.
2. Chapter 11
· Sta~ed Implementation - System masters can be · System Implementation
implemented in stages when funds are available or · Procurement Approach (of Consultants and
the need for centralized control is warranted. Contractors)
· Design Plans and Specifications
· Multi-Level (Hierarchical) Central Operation - {includes bid process)
Multiple system masters can be coordinated and · Deliverable Services (includes documentation,
monitored from one personal computer, training and maintenance)
· Project Management (includes contracts and
· Extensive System Back-Up - All traffic data and scheduling)
system failures can be saved for future use. o Implementation Pitfalls
This function is important in providing a
historical traffic data base for future timing Another important source of information is agencies
plans and potential litigation, that have implemented a closed loop system. Traffic
engineers from these agencies will provide insight
Factors in Selectinq A Closed Loop System into selection, design, advantages and pitfalls of
closed loop systems.
The intent of this section is to provide a review of
topics when considering the implementation of a closed CLOSED LOOP SYSTEM COMPONENTS
loop system. The selection a closed loop system can
be a challenging task. Even the most experienced A typical closed loop signal system primarily consists
traffic engineers occasionally overlook elements of of a personal computer (PC), traffic control software,
the system selection process. A few of the basic system masters, local controllers, communications bet-
questions which should be asked during this process ween the PC and system master and between the system
are as follows: master and the local controller as well as sampling
detectors and signal hardware. This section is
· Does the Agency have traffic signals which are intended to provide a very brief overview of a few of
applicable to a closed loop system? these components. The components of the closed loop
system are illustrated in Figure 1.
· Who is going to design the signal system, and
investigate which system(s) is best for the Computer Hardware and Software Needs
Agency?
The personal computer is the center for monitoring the
· How does the Agency justify the expense of a closed loop system. All closed loop system manufac-
closed loop system? turers are moving toward the use of IBMtm and IBMTM
compatible personal computers. Previous systems have
· Does the Agency have the experienced personnel to also utilized Appletm computers. Color graphic
operate and maintain the system? capabilities and at least ten-megabyte hard disk data
storage are useful in all new closed loop system
· Can existing traffic control equipment be uti- installations.
lized with the new system?
The traffic control software provided with each closed
· Does the potential manufacturer have an estab- loop system is the heart of the central computing
lished track record of successful systems? facility. Most advancements in closed loop systems
in the last few years have come in this area. A sub-
· Will the successful manufacturer provide suf- jective evaluation of closed loop system software is
ficient installation guidance of equipment, impossible for this paper. A few topics such as the
training of city staff and on-site support? number of system masters per system manager,
restricted access to the traffic control software and
· Who is going to inspect and approve the installa- report generation are mentioned in a latter section of
tion of the system? this paper. A comparative review of the closed loop
system software by all responsible technical personnel
An important step in the implementation of any signal is recommended. A few questions which should be asked
system is the development of system specifications, concerning traffic control software are as follows:
Specifications detail the minimum acceptable require-
ments for equipment and system installation. Open · Is there a real-time intersection graphics
specifications help ensure competitive bids on equip- display?
merit. Closed specifications, or specifications writ-
ten toward one manufacturer, may lead to uncompetitive m Can real-time arterial signal timing changings be
bidding, displayed?
ITE 1988 Compenc[ium of Technical Papers/136
~k)ad System Stattm
Tm~g ~/~ Failure I=leport~
Syst~
~er
I~~ ~ ~tec~ Da~
~n~o~r
~mpOng ~tectors Signal I~i~tion
FIGURE 1. CLOSED LOOP SYSTEM COMPONENTS
e Can traffic signal timing program outputs (such When using a system master and local controller from
as T~ANSYT-7F) be directly downloaded into the the same manufacturer, the likelihood of installation
timing plans at the personal co~uter? and co~nications problems are reduced. The com-
bination of existing NEMA-type local controllers and a
~ Is it possible to request a download of signal manufacturers' system master can reduce the initial
timing plans from the field when the personal capital outlay. The latter hardware combination
co~uter is unattended? requires an external communications unit to interface
the local controller with the system master.
~ What intersection timing co~onents are displayed
at the personal co~uter? Co~nications
You will find in your review of closed loop system The effectiveness of all traffic control systems
software that there is a vast difference in capabili- depends on the reliability of the co~nications net-
ties and graphic displays among the systems, work between the central control facility and each
Determine your needs and weigh these against the costs signalized intersection with the system. Experience
of the closed loop system, shes that a ~ood portion of proble~ occurring during
installation are related to co~nications. For this
On-Street System Master and Local Controllers reason due care should be taken in the selection of
the co~nications link. The factors governing the
On-street system masters and local controllers selection of a co~nications link are as full,s:
co~rise the bulk of the hardware for any traffic
control system. With respect to closed loop systems, e Economic Factors - Should the co:nications link
the system master and local controller arrangements be user-~ned, leased, shared or a combination of
can be split into two categories. The most prominent the three?
category involves the combination of system masters
and local controllers from the sa~e manufacturer. The e Technical Factors - Has the co~nications link
second category incorporates the manufacturers system demonstrated previous reliability? Can any
master with existing NEMA compatible, local existing com~nications facilities be incor-
controllers. The manufacturers' system master and porated into the closed loop system? Overhead
local controller along with addresses and references vs. underground?
are sh~n in Table 1.
)TE ~988 Compend)um o(Techn~camP~peFs/137
TABLE 1. CLOSED LOOP SYSTEM MANUFACTURER INFORMATION
SYSTEM LOCAL
COMPANY/SYSTEM ADDRESS MASTER CONTROLLER REFERENCES
1. Eagle Signal Controls/ 8004 Cameron Road Dalton, GA
MARCTM Traffic Management Austin, TX 78753 Burleson, TX
and Control System (512) 837-8300 MARC 360 EPAC 300 Roswell, GA
2. Econolite Control Products, 3360 E. La Palma
Inc./Zone Monitor 3 P.O. Box 6150 Amarillo, TX
Anaheim, CA 92806 ASC-8,000 Santa Fe, NM
(714) 630-3700 KMCE-IO,O00 KMCE-8~O00 De Kalb County~ GA
3. Kentron, Inc./1700 PC P.O. Box 13221
Closed Loop System Houston, TX 77219 Jefferson Parrish, LA
(800) 392-2206 ~MT 1700 KMT 1700 Harris County, TX
4. Minnesota Microtronics P.O. Box 235
(2M)/Remote Master System 311 12th Ave. South
(RMS) Buffalo, MN 55313
(612) 682-3516 SM 5000 SL 8000 Hennepin County~ MN
5. SONEX/ZDC Closed Loop 931-939 E. Lycoming St. Fort Sill, OK
Distributed Traffic Control Philadelphia, PA 19124 Any NEMA Norfolk, VA
System (215) 533-4900 S8005 Type* College Park~ MD
6. Traconex, Inc./TracoNetTM 336 Martin Avenue Charlotte, NC
Santa Clara, CA 95050 Chattanooga, TN
(408) 727-0260 TMM-500 TMP-390 Marina, CA
7. Traffic Control Technology Cross Roads Park LC 2000/
(TCT)/LM 100 Closed Loop P.O. Box 0399 8000 or Piano, TX
System Liverpool, NY 13088 Any NEMA Los Alamos, NM
(315) 451-9500 LM 100 Type* Fort Wayne, IN
8. Transyt Corporation/3800 4920 Woodlane Circle LS 3800 or Greenville, SC
Closed Loop System TaIlahassee, FL 32303 Any NEMA Gainsville, FL
(904) 562-2253 3800 Type* Denton, TX
9. Winko-Matic Signal Co./OSAM 630! Best Friend Road Des Moines, IA
32TM Traffic Responsive On- Norcross, GA 30071 Elgin, IL
Street Master Closed Loop (404) 662-5400 OSAM 32tm 820Atto I Covington, GA
System
* - Must use an external communications unit
Several alternative communication links are available SELECTIVE CLOSED LOOP SYSTEM ITEM LISTING
on the market today. The most commonly used com-
munications medium in closed loop systems is the A listing of selected closed loop system components
twisted-wire-pair cable. The majority of these cables for each manufacturer can be found in Table 2. This
are user-owned. The biggest disadvantage of user- information was gathered in part from company
owned vs. leased cable is the high initial capital brochures and from telephone conversations with per-
outlay for installation, Some advantages of user- sonnel from each manufacturer. Every effort was made
owned cable are: easy system expansion, flexible to provide an accurate and up-to-date listing for each
design of the communication network and full control system. This table provides a few of the many capabi-
of the communication network to name just a few. lities of the closed loop system as well as system
backgrounds. The following list parallels Table 2 and
Two other common mediums are coaxial cable and cable offers a few comments about each item:
TV (CATV). These are both viable mediums and should
be considered in the selection process. Less common 1-3. The maximum number of intersections controlled
communication links are fiber-optic, laser and is a function of the number of local
microwave communications. An i ndepth discussion of controllers operating per system master and the
the alternative communication links can be found in number of system masters operating per system
"Chapter 8 Communications" of the 1985 Traffic manager (personal computer).
Control Systems Handbook (10).
I'FE 1988 Compendi.um of Technical Papers,'138
TABLE 2. SELECTIVE CLOSED LO0~ ~FSTEM ITEM LISTING
ITEM ~ ~ ~ ~
1. Number of system masters/system manager 16 24 Unlm, 24 14 31 16 36 16
2. Number of local controllers/system master 32 24 32 30 32 31
3. Maximum number of intersections controlled 512 5 76 UnlmJ 720 448 961 384
4. Total sub-systems per system master 2 1 n.a. 1 lO 31
5. System detector capacitya,b 64 32 256 32 112 248 24 48 256
6. First year on the market 1985 1982 1986 1986 1984 1984 1985 1982 1986
7. Approx. number of systems on the market 25 400 3 4 15 80 83 70
8. Guaranteed price on expansion controllers y y y y y Y Y Y n.a.
g. Warranty (years) 2 5 2 ! 2 n.a.
lO. Training available Y Y Y Y Y Y Y Y Y
Il. Restricted access to control software y y Y Y Y N Y Y Y
1~. Operating Modes
m Traffic Responsive Y Y Y Y Y Y Y Y Y
~ TOD/DOW Y Y Y Y Y Y Y Y Y
· Manual Y Y Y Y Y Y Y Y Y
13. Signal Timing Con~)onents
m Total number of cycles 4 6 6 6 n.a. 6 4 6 n.a.
m Total number of splits 4 4 4 4 n.a. 3 4 12 n.a.
m Total number of offsets 3 5 5 5 n.a. 5 3 5 n.a.
m Total traffic coordination patterns ¢8 120 120 120 n.a. 90
14. Time Base Capability Y Y Y Y Y Y Y Y Y
15. Number of Stand Alar~ lO n.a. 8 12 8 15 n.a. 4 n.a.
16. Number of User Defined Alarms 6 n.a. n.a. 0 n.a. n.a. n.a. 5 n.a.
17. Alarm Reporting
{via call-up feature) Y Y Y N Y Y Y Y Y
18. Number of Preempt Sequences 4 lO 6 5 3 5 4 5 5
19. System ~iOE's
· Speed Y Y Y Y Y Y Y Y Y
· Delay Y Y N N N N N n.a. N
· Occupancy Y Y Y Y Y Y Y Y Y
m Traffic Volumes Y Y Y Y Y Y Y Y Y
20. Report Generation
· Failure (Alarm) reports Y Y Y Y Y Y ¥ ¥ ¥
· System status reports Y Y Y Y ¥ Y Y ¥ ¥
· System and local detector reports Y Y Y Y Y Y Y Y Y
m Traffic pattern reports Y Y N N Y Y Y Y Y
a - Per master
b - Check current manufacturer literature for detector capacity descriptions
Unlm. - Unlimited
n.a. - Information not available
ITE 1988 Compendium of Technical Papers/139
4. A subsystem of a system mas~er effectively uti- SUM~RY
lizes the system master for two or more signal
control groups. One system master, as an A brief overview and listing of closed loop signal
example, could manage the signal control of two systems have been presented in this paper. The closed
crossing arterials as long as the total number loop system concept including system advantages and
of local controllers per system master is not system selection processes have been reviewed. Closed
violated, loop system components such as computer hardware,
traffic control software, system masters, local
5. System detectors are used in the calculation of controllers and communications are briefly discussed.
timing pattern changes and system measures of A listing of nine closed loop systems for selected
effectiveness, items are presented.
6-10. The first year on the market, total systems on Careful consideration should be given to the selection
the market, price guarantees, warranties of a particular closed loop system. Each system has
(years) and available training are indicators its own unique benefits. Closed loop signal systems
to be considered, offer an excellent alternative to the larger more
expensive mainframe and minicomputer based systems.
11. Most all closed loop systems restrict the
amount of access available to the traffic REFERENCES
control software. The majority of systems use
passwords to restrict access to intersection 1. "MARCTM Traffic Management and Control System."
monitoring, data base information and signal Eagle Signal Controls, Austin, Texas, 1987-88
timing downloading. (Product Brochure)
12. All systems are capable of operating traffic 2. "KMC Master Monitor Multiple Arterial Management
responsive, time-of-day/day-of-week and manual. System." Econolite Control Products, Inc.,
Anaheim, California, 1987-88 (Product Brochure)
13. All systems offer more traffic coordination
patterns than can probably be used. 3. "1700PC Closed Loop System." Kentron, Inc.,
Houston, Texas, 1987-88 (Product Brochure)
14. Time base capability is inherent in all closed
loop systems. 4. "Minnesota Microtronics Traffic Control System."
Minnesota Microtronics, Inc., Buffalo, Minnesota,
15-17. All systems offer some combination of standard 1988 (Product Brochure)
and user-defined alarms. A few examples
include door open, conflict flash, manual 5. "ZDC Closed Loop Distributed Traffic Control
control enable and detector failures. It is System." Sonex, Philadelphia, Pennsylvania,
preferable to have a system report alarms to at 1987-88 (Product Brochure)
least two potential locations.
6. "TracoNettm." Traconex, Inc., Santa Clara,
18. Preempt sequences are used for fire and ambu- California, 1987-88 (Product Brochure)
lance services as well as trains.
7. "LMiO0 Closed Loop System." Traffic Control
19. Utilizing the system and local detectors as Technologies, Liverpool, New York, 1987-88
traffic data collectors, system measures of (Product Brochure)
effectiveness (MOE) can be calculated. Speed,
delay, occupancy and traffic volumes are among 8. "3800 Closed Loop System." Transyt Corporation,
most of the system MOE's calculated. Tallahassee, Florida, 1987-88 (Product Brochure)
20. Almost all systems generate reports on failures 9. "OSAM 32tm Traffic Responsive On-Street Master."
(alarms), system status, system and local Winko-Matic Signal Companytm (Multisonics Corp.),
detector status as well as changes in traffic Norcross, Georgia, 1987-88 (Product Brochure)
patterns. Ask for samples of all reports
generated by the system software and compare 10. Traffic Control Systems Handbook. U.S. Department
outputs, of Transportation, Federal Highway Administration,
April 1985.
Cost considerations have been purposely omitted due to
price fluctuations in the market.
ITE 1988 Compendium of Technical Papers/140