McTrans Newsletter
June, 1995

HCS "Patch"

New Method of Updating

Since the distribution of the Highway Capacity Software (HCS), there have been a few reports of minor problems. As of May 31, there have well over 1,000 copies of the new HCS distributed, either as upgrades or new purchases. As the new software gets into more users' hands, questions and problems are forwarded to McTrans . Many reports have just been users getting familiar with the updated Highway Capacity Software (HCM) procedures, and in some cases the new interface to the software or the installation process. However, there have been functional issues in the way the HCS automates these new procedures that we must address.

As problems are reported, we check out the procedures in the HCM to ensure these are being replicated accurately. In a few cases, the procedures have been implemented correctly, but not all situations were covered. Some reports involve the design for data entry or report formatting. We have been tracking all reports very carefully, giving them our highest priority.

We are targeting the month of July to provide the first "patch" to the HCS. During the installation of the HCS, a program was transferred to your HCS subdirectory which will facilitate any updates we issue. We will develop a file for distribution that will use this program to update any affected program files. The "patch" file will be made available through our electronic bulletin board, McLink, and through the mail for anyone wishing not to download it electronically.

This will be a continuous process for keeping the HCS, and any other McTrans -maintained software, as current as possible. The "patch" files will be cumulative so any time you retrieve one and run it to update your program, all fixes since the last formal mailing will be included. This "patch" file modifies, not replaces, the program files to be updated. This keeps the size of this file small for quick downloading through McLink.

So, all HCS users be on the lookout for the first update via McLink. We think this process will revolutionize how efficiently programs can be kept maintained and make the process of getting these changes to you much more effective.

Guidelines for Using Signalized Intersection Capacity Analysis in Traffic Impact Studies

By Jeffrey A. L'Amoreux, P.E.
Manager, Traffic Operations and Systems
Carroll Engineering Corporation
Fred L. Orcutt, Jr. P.E.
Manager, Traffic Operations and Systems
Piedmont Olsen Hensley, Inc.

Traffic is burgeoning in many areas of the country. Government agencies and private developers alike are turning more and more to studies involving highway capacity analysis to determine the effects development is expected to have on existing and planned roadway networks and the remedial measures requires to mitigate these effects.

Procedures for performing the capacity computations required by traffic impact analyses are well-documented in the Highway Capacity Manual (HCM) and many computer programs are available to automate them. This article addresses the capacity computations of greatest use in traffic impact analysesÄthose for intersections controlled by traffic signals, as documented in Chapter 9 of the HCM.

This article was prompted by two facts. First, increasing numbers of traffic engineers and technicians new to the field of capacity analysis "learn" the rudiments of signalized intersection capacity analysis by operating one of the available computer programs, instead of mastering the Highway Capacity Manual procedures through manual analysis. While this method lead quickly to "answers", it is ineffective in providing the depth of understanding needed by such users. Thus, the "answers" to intersection capacity questions are often wrong!

Second, while the computation procedures are well documented, their use is open to abuse, because most agencies have not established appropriate guidelines. The net effect has often been that the results of signalized intersection analyses have been skewed by the choice of the capacity analysis parameters.

The purpose of this article is to improve understanding of capacity analysis and to suggest appropriate analysis parameters. A few parameters of interest in this regard are level of service, ideal saturation flow rate, arrival type, and peak-hour factor.

Level of Service

Level of service (LOS) is a measure of how well a signalized intersection is expected to function. Seven levels of service are based on expected average stopped delay per vehicle, as shown in Table 1. In selecting a target level of service it is important to consider the quality of existing traffic flow, the desired quality of future traffic flow, and what improvements can reasonably be implemented in an area. This decision may vary from intersection to intersection because of the "reasonable improvements" issue.

Level of Service........ Average Stopped Delay Per Vehicle (seconds).......... Comment

A........... 5.0 or less Very good operation
B........... 5.0+ to 15.0 Good operation
C........... 15.0+ to 25.0 Acceptable operation
D........... 25.0+ to 40.0 Congestion
E........... 40.0+ to 60.0 Significant congestion
F........... More than 60.0 Unacceptable operation
Breakdown... Very high Condition so poor that capacity calculations are meaningless

Target levels of service may be set as a matter of policy by the governmental agency having jurisdiction over the intersection. In dense, congested areas where physical improvements are difficult to achieve, is may be necessary to settle for a reduced level of service. In such cases, it should be clearly recognized that the result will be some degree of Congestion. Agencies should be very careful about accepting a target LOS of E or worse. Such a decision could guarantee significant congestion for years to come.

Ideal Saturation Flow Rate

Ideal saturation flow is the parameter that represents the basic capacity of a traffic lane in vehicles per hour (vph) of green time. Usually, this is an indication of motorists' aggressiveness. The HCM suggests a default value of 1900 vph per lane. Generally, 1900 vph is a reasonable value. In rural areas and "sleepy" towns, you might reduce it. In heavily congested areas it may warrant raising. Any adjustment of the ideal saturation flow rate, however, should only be done on the basis of documented actual measurements. Such measurements, if necessary, should be made for a lane at the intersection (or another intersection, if necessary) that approximates ideal conditions. (If another intersection is used, it must exhibit a comparable saturation flow rate to the intersection under study.) Use of arbitrarily higher saturation flow rates can cause otherwise congested intersections to appear to be acceptable from the capacity calculations. Use of an arbitrarily lower value can cause an intersection which actually will function quite well to appear to be congested.

Arrival Type

Arrival type, with values ranging from 1 to 6, addresses the type of traffic flow that can be expected from traffic signal coordination. It is used to develop a factor for adjusting the ideal saturation flow up or down. The lowest value 1, indicates that platoons of traffic consistently arrive at the beginning of the RED traffic signal. The highest value, 6, indicates that most platoons consistently arrive at the beginning of the GREEN signal. For signals that are not part of a coordinated system, a value of 3 (approximating random arrivals) should be used.

A value of 3 should generally be used for capacity analyses, unless it can be demonstrated through a signal timing analysis, specific to the time of day corresponding to the analysis, that good "beginning of GREEN" progression can be achieved. Often an Arrival Type 5 or 6 is assumed by elevators simply because the subject intersection is or will be part of a coordinated traffic signal system. Such a condition, however, it not a guarantee of good progressed traffic through any specific intersection. Indeed, that is often not the case even in well- timed systems.

Peak-hour Factor

Peak-hour factor (PHF) is a measure of traffic peaking during the period of the analysis. It is also used to adjust the ideal saturation flow. The range of the PHF is from 0.25 to 1.0. 1.0 indicates very regular traffic where essentially the same amount of traffic arrives at the intersection in each 15-minute period. Conversely, a PHF of 0.25 would indicate that all of the traffic arrived at the intersection during the same 15-minute period and no traffic was processed during the other 45 minutes. From a practical standpoint, choosing a higher PHF than appropriate might result in unexpected congestion following development.

Peak-hour factors should be determined for each intersection approach from 15-minute increment "movement"-type traffic counts. Once the counts are available, the computation is simple. It is reasonable to assume that peaking might be reduced as traffic increases.

Traffic Signal Timings

Traffic signal timings have a dramatic effect on the results of capacity analyses. Sometimes timings are assumed by the evaluator and can favor his goals. Existing timings should be used for capacity analyses unless a signal timing analysis shows that revised timings provide better service. This judgement should take into account the service at all intersections within coordinated signal systems.

"Mac" Trans, by Bill Allen

tell. to hard its but functions, similar have will or do either 2) OS probably (and Windows that suspect I programs. (TSR) resident? stay andterminate>On the Mac these programs are called "INITs" (presumably short for "initialization") and are stored in either the Control Panels or the Extensions folder in the System folder. There are hundreds of such programs available, many of which are share- or free-ware. They perform a wide variety of tasks and rapidly become an indispensable part of everyone's Mac.

Here are the INITs that I currently use:

 Last Resort: There is nothing more irritating than suddenly losing a well-crafted paragraph or two to a power outage or crash. This program automatically captures every keystroke into a buffer that is continuously saved, sparing you hours of grief.
 After Dark: Even though it a myth that color screens suffer image burn-in, screen savers are one of those applications that are so neat, you just can't resist.
 Kaboom!: Another fun INIT that plays all kinds of user- selected sounds at certain events (opening of a file, insertion of a floppy disk, etc.).
 SAM Intercept: Symantec Anti-Virus for the Macintosh scans the system upon startup and looks for all kinds of evil things lurking around the hard disk and floppy drive.
 Norton File Saver: Another "safety" featureÄthis program greatly facilitates the retrieval of accidently deleted files.
 Working Watermaker: This unusual program places a false "watermark" on any document. It puts a gray shaded version of any text or drawing behind the normal (black) images on a page. Handy as a subtle "Draft" stamp.
 PC Shift: An annoyance of the Mac is that when the Caps Lock key is down, you can't press the Shift key to momentarily obtain a lower-case character, as you can on most DOS machines. With this program, you can.
 Norton Directory Assistance II: This program replaces the standard Mac "Open File" dialog box of just about all applications with a more complete one that adds numerous handy file finding features.

This seems to be about an average number of INITs. I try to resist the temptation to add more, because having too many INITs can lead to system conflicts which mess up your Mac in ways that are difficult to detect. So far, these eight have not had not problem.

International Conference on Advanced Traffic Management Systems (ATMS)

Bridging the Gap to ATMS Deployment

October 1-6, 1995
Tradewinds Resort and Conference Center
St. Petersburg Beach, Florida
The essence of Advanced Traffic Management Systems (ATMS) is an improved ability to manage transportation services by providing accurate and reliable real-time information to both the motoring public and the transportation system itself. The ability to obtain and disseminate this information has improved dramatically over the last few years, thanks in part to public-private partnerships and to continuing research and development. This international five-day workshop is aimed at discussing the issues surrounding ATMS to define its deployment over the next decade, and to assess user needs and current directions. Namely, we want to build bridges to the deployment of ATMS.

Among others, the following topics, as they relate to ATMS deployment, will be covered: operations and maintenance, hardware and software issues, technology transfer, standards and protocols, research & development, and institutional, legal and financial issues. Other issues to be addressed include ATMS products being developed, what and when users expect them to be available, and how the users' current and future requirements are being met. The outcome of this workshop will be the definition of the requirements for ATMS deployment, identification of constraints, assessment of potential solutions to the identified impediments, and a set of recommendations for the development of ATMS deployment guidelines.

To create an informal atmosphere and encourage discussion, the format of the conference will consist of morning and evening sessions and workshops with ad-hoc discussion and demonstrations in the afternoons. The ITS America ATMS committee will also hold a meeting during the conference, and its Digital Maps and Spatial Databases Subcommittee will be meeting as an integral track.

The registration fee for this five-day workshop is $700 if received prior to August 1, 1995, and $800 after that date. The fee includes the workshop, workshop proceedings, lodging (single accommodations) for Sunday through Thursday nights, and some meals. Double accommodations are available at a reduced cost if appropriate arrangements can be made.

A limited number of scholarships will be available for public-sector (state and local) participants as well as college students majoring in transportation and graduating by June 1996. Participation at this workshop is being expanded (relative to the October 1993 conference) to ensure a wide international representation, but attendance will be limited.

The conference is sponsored by the Federal Highway Administration (FHWA), Oak Ridge National Laboratory (ORNL), the University of Florida (UF), and the ITS America ATMS Committee.

To register, complete and return the attached registration form. For information, contact Ms. Laurie Neff, ATMS Workshop Coordinator, McTrans Center, P.O. Box 116585, 512 Weil Hall, University of Florida, Gainesville, FL, 32611-6585, Tel: (352) 392-0378, fax (352) 392-3224, e-mail: .



STP is a Sign Inventory Package with a CADD library of over 300 sign drawing files that can be used in signalization, signing and marking, and other traffic control plans. Each Package can be ordered in DWG, DXF, or CEL formats. The DWG format was drawn using AutoCAD Release 12 and can be used with other releases of AutoCAD. The CEL format was drawn using MICROSTATION Version 5. This, however, is the only version that can use the CEL Sign Inventory Package. The DXF format was created using the AutoCAD DXFOUT command. The DXF format can be used in many other CADD packages. All drawings can be edited to reflect the specific needs of your projects.

The SIP also includes a drawing file containing all the signs. This file can be plotted to show the entire package on a 24" x 36" sheet of paper.

SIP (#SIP) from David Howell is available for $175 at LOS 6.


WINcogo (R) is a standalone coordinate geometry program for the Windows environment. It will run under Windows ver. 3.1 or later and Windows NT (R). Hard drive space required is approx. 800K.

The short "learning curve" of WINcogo allows the firms that would like to upgrade their coordinate geometry to Windows the opportunity to do so without excessive lost time. WINcogo will transfer data directly to CAD programs (AutoCAD(TM) or MicroStation(TM)). The algorithms used in the WINcogo routines have been in use, in other software written by the program developers, since 1978 and have been well tested.

Some of the features included are:

 Uses double precision math
 Stores XY&Z ordinates (feet or meters) and 15 character point description
 Traverse computation including closure and adjustment by:
Compass Rule
Transit Rule
Crandal Method
 Data scaling
 Data rotation
 Data translation
 A myriad of geometry routines such as:
arc x arc intersection
bearing x bearing intersection
arc x bearing intersection
offset from line
offset x offset intersection
parallel line
multiple offset x offset intersection
multiple parallel line
pre-fixed areas
radial inverse
point to point inverse
point to point traverse
point to point area (including arcs)
 Automated intersection, cul-de-sac, eye-brows and building envelope computations
 Check closure of maps by manual input of data obtained from hardcopies. Data may be stored for editing.
 Prepares outline descriptions including curve data. The ability of the program to generate descriptions directly from the coordinate data eliminates the possibility of scriveners error. Descriptions around arcs are handled properly with direction of arc (left or right), delta, radius, arc length, chord length and chord bearing given.
 Radial traverse and radial stakeout
 Curve computation by 6 different methods
 Computation of degree of curvature by arc & chord methods
 Video plot of data
 Generation of DXF files complete bearings, distances, point nos., etc.
 Direct import/export various ASCII formats including Geodimeter(TM) format
 Allows input and output using bearings, south azimuths or north azimuths

WINcogo (#WINCOGO) by A&G software is available at LOS 6 for $145.00.

MetriCAD for Windows

MetriCAD for Windows(tm) offers interactive modification and updating of dimensions in any AutoCAD(tm)- compatible .DXF file. Convert any of millimeters, centimeters, meters, kilometers, inches, feet, feet'-inches",, yards, miles to any other (conversion to feet'- inches" not supported). Convert degrees, radians, or grads to any of the other. Convert acres to hectares, or vice versa.

MetriCAD preserves your source drawing, allowing you to create multiple sets featuring different dimension types.

You have complete control over significant features and decimal places, can append the revised dimension to the existing dimension, and can select whether to or not to display a dimension descriptor, e.g., mm, ft., etc.

Comprehensive online help, and manual in Windows(tm). Write format.


Quick Response System II (QRSII) for Windows has been upgraded to utilize the many improvements made to the General Network Editor (GNE), and to keep QRS II for Windows on the cutting edge of travel forecasting technology. The General Network Editor has undergone the first major overhaul since it was converted to Windows. The revision greatly increases GNE's power, both as a graphics tool and a data preparation tool. Dialog boxes and menus have been revised for speed and clarity. Here is a partial list of the improvements included: A new program feature enables information to be readily available as Area, Perimeter, and Center of Gravity, and to be utilized in the Calculate Feature of the Advanced GNE. There are new Sketch Pad options for Link Direction, Polygon Insert and Polygon Delete. A new BASIC-like Calculate Relation Syntax provides more Boolean Operators and Real Functions; as well as subroutines, branching, iteration, and Sketch Pad Refresh. There are additional sample programs, and increased capacity for longer programs. All selections affecting the look of the network are saved with the network. For easier editing, there is Fast Zooming in twelve increments from 1:12 to 6:1 without rescaling.

In QRSII for Windows, highway links now can be given a functional class, and different sets of BPR curve parameters can be applied to each functional class. Delay reports are easier to read. Delay relationships are available for ramp meters. Runs involving equilibrium iterations and transit networks are much faster. Trip attraction equations can use two new centroid attributes, called "Demographic 4" and "Demographic 5", which are entirely user-definable. The balancing of productions and attractions can be varied by trip purpose. Urban area size break points are user- selectable. A new friction factor function, combining the exponential and power function, has been added. Highway link volumes can be identified by origin and destination zones ("select zone analysis"). The value of time used in transit disutility equations can be varied by trip purposes. Up to 2 additional types of transfer points can be defined. Transit networks can be much larger, allowing up to 32,000 internal links in the larger editions. Parameter files can be placed in any directory (an important feature for anyone using a LAN or for a group of people sharing one copy of QRS II). QRS II (#QRS.XXX) for Windows and the Advanced General Network Editor (#GNE.WIN) are offered at LOS 7 and each come with a comprehensive Reference Manual, at a package cost of $390 for both, with 300 zones. Additional zone increments can be added.

TRAF 5.0 Available

The TRAF family of programs has been updated to version 5.0. The TRAF-NETSIM, CORFLO and FRESIM packages and their components have been sent to registered users. Some detail on the specific changes are discussed below.

TSIS version 3.30 includes updates to reflect new error messages for CORFLO, TRAF-NETSIM, and FRESIM models. The menu includes an option for CORSIM which applies only to the beta test version which is not included in the update. GTRAF option has been added to the menu replacing ANETG and SNETG. The front end menu now checks memory for GTRAF and GCOR execution which require 6MB of free extended memory.

TRAF-NETSIM version 5.0 now includes new multi- movement lane codes, intra-link lane-change logic, and detailed intersection simulation logic. Additional actuated controller features include left turn extension, lag left turn hold, conditional service, and simultaneous gap out. The left-turn lager turn probabilities were modified to resemble more realistic values. The defaults for signal transition logic code is set to 1 if left blank and the start-up lost time and discharge headway are revised to 2.0 and 1.8 seconds to reflect studies conducted by NCHRP. Surveillance logic has been revised to enhance gap and headway computations so that detection zones around sensors are properly defined (i.e., more gaps between vehicles are detected). Urban interchange simulation capability was added so that OD data can be used as input instead of turn movement percentages for each link within the interchange. Enhancements include link aggregation input allowing any combination of links for MOE reports and revised output routines to properly report number of lane changes on a link after FILL time. Subsequent time period input requirements for pre-timed signal plans are required only for signal plans that change. This version corrects a memory overflow problem when an entry link with only diagonal traffic is specified and corrects an improper data transfer between actuated signal control and traffic assignment which lead to generating unacceptable paths by the assignment logic. Buses can now change lanes around a blockage if enough room exist for the bus to return to the curb lane.

CORFLO version 5.0 update includes revisions to correct a signal offset error, vehicle scheduling process in NETFLO 1 which caused an indefinite loop, a FREFLO logic error in reporting the total number of lanes to the graphics processor NETFLO2, and an error in reporting exit interface cumulative statistics when the length is less than 100 feet. CORFLO has been modified to handle 2000 links and 700 nodes with the following limits FREFLO, 500 links and 250 nodes; NETFLO1, 700 links and 500 nodes; and NETFLO2, 1500 links and 500 nodes.

FRESIM version 5.0 corrected numerous memory corruption and minor input data checking errors; enhanced several output tables and MOEs, lane add/drop features on ramp links, logic for multiple freeway segments; increased the maximum number of vehicles that can be processed to 10,000; added logic to allow graphics post-processing of FRESIM output; and added logic to issue error message 6252 when the number of lanes on an entry link and its receiving link are not equal. Changes to the data editor, Fedit, allow negative "fill time" and changed all "mean queue discharge delays" to "mean startup delays" in the Link Geometry and Operations screens.

GTRAF version 5.0 combine SNETG and ANETG in the GTRAF.EXE, which requires a 80386/80387 CPU or better and operates only in extended memory mode. GTRAF requires at least 8 MB of extended memory to run (with 6 MB available at execution time) and requires GSS-GKS device drivers version 2.3 or higher. The GTRAF software have enhanced menus and support only the TRAF-NETSIM 5.0 graphic output files. The most significant improvement include continuous display of animation frames for most data sets. The current logic allows up to 2400 frames per each file I/O operation. It can display up to 2400 seconds of information in the "FAST" setting and up to 300 seconds of information in the "SLOWEST" setting before a second I/O operation is performed. The actual number of display frames is dependent on the number of vehicles in the viewing area. This version corrects a GTRAF crash when the user selects an OD pair that has no demand (traffic assignment module), corrects minor display problems in pedestrian graphics associated with actuated node controller snapshots, and sets the default entry link length (for graphics display purposes) to 200 feet if the average network link length is greater than 200 feet, and to 100 feet if the average network link length is less than 200 ft.

GCOR version 5.0 now requires 80386/80387 CPU and operates in extended memory mode only. At least 4MB of memory is required to run. It also requires GSS-GKS device drivers version 2.3 or higher.

TRAFEDIT version 1.30 include updates to incorporate data entry options for version 5.0 of TRAF-NETSIM and CORFLO data requirements.

The TRAF-NETSIM, CORFLO and FRESIM packages and their components have been sent to registered users.

TRAFFIX from Dowling, Associates has been upgraded to version 6.8.

It has the Highway Capacity Manual update 1994 methodologies for chapters 9, 10, and 11. Along with the new 1994 HCM methodologies, various features in the intersection analysis procedures and been upgraded, and many user-friendly features added. Specifically, volume adjustments for passer-by trips and the ability to read EMME/2 turning movement files.

The TRAFFIX manual has been updated. The manual is divided into three parts: Getting Started, Reference Manual, and Technical Notes.

We are providing the upgraded software for a fee of $300.00 to all registered TRAFFIX users.

TRAFFIX VERSION 6.8 upgrade (#TRAFFIX) by Dowling Associates is available to all registered TRAFFIX users at LOS 7 for $300.

WINUNSIG version 2.0 update

WINUNSIG is a program developed for Microsoft Windows to provide a fast and simple method to analyze unsignalized intersections. Enter the volumes for each movement, click on a few controls to indicate intersection geometry, and the analysis is complete and ready to print. The analysis results are updated automatically every time a change is made. The printed report presents the data in both graphical and tabular form for four legged and three legged intersections. The windows used to display the Summary, Volumes, Geometry, and Worksheet can be printed at any time with just one click. The tabulated data displayed in the Summary Window can be copies and pasted into other Windows program for inclusion in a traffic report or into a spreadsheet for further analysis. WINUNSIG supports the Windows Multiple Document Interface (MDI) allowing several four legged and three legged intersections to be displayed simultaneously.

Major improvements in WINUNSIG version 2.0 include: An extensive Windows on-line Help system; Support for the Windows MDI; Direct Entry of Peak Hour Factors; Support for entering individual volumes as a percent of total volume; Controls for adjusting the average running speed of the major street in 1 mile per hour increments from 20 MPH to 65 MPH; An option to print a Traffic Composition report in addition to the HCM style report; File management capabilities to create directories for each project; And many 'behind-the-scenes" improvements for smoother operation. WINUNSIG version 2.0 employs the methods of chapter 10 of the 1985 Highway Capacity Manual. Version 3 is currently under development to use the methods just released in the October 1994 version of the Highway Capacity Manual. Purchase WINUNSIG version 2.0 now and get a free upgrade to version 3.0 (less shipping and handling) scheduled for release in July of this year.

WINUNSIG will run on any computer with 4 megabytes of RAM, a VGA monitor, Windows 3.1 or higher, and a mouse. A super VGA monitor is recommended. WINUNSIG (#WINUNS) version 2.0 is offered at LOS 7 by Roderick K. Lovely, P.E. of Center Ossippe, NH for $75. Complete documentation for version 2.0 is provided in the on-line Help system. A manual will be provided in the version 3.0 upgrade.