Includes highway safety publications and journals on road maintenance, engineering and injury litigation, as well as traffic safety facts, accident and collision investigation information and consulting, court and liability issues, and links to transportation related organizations such as departments of transportation and safety organizations.  Also includes discussion of road construction issues, legal cases on traffic accidents and collisions, and other information on highway safety.  See our highway safety expert services and publications.
Road Management Journal
Copyright © 1997 by TranSafety, Inc.
August 11, 1997
TranSafety, Inc.
(360) 683-6276
Fax: (360) 335-6402

Swareflex Wildlife Warning Reflectors: One Preventive Measure for Wildlife-Vehicle Collisions
Discussion of Sign Management Technologies
Questions with Answers from a Gravel Road Expert
Announcement and Call for Papers: Seventh International Conference on Low-Volume Roads
Tires: A New Source for Culvert Pipe

Highway Safety Publications Catalog. Articles on Road Engineering, Road Maintenance & Management, and Injury Litigation. Information and consulting for the Automobile and Road User, as well as for law professionals in accident investigations.
TranSafety's free consumer journal for automobile and road users, three subscription journals on road maintenance, engineering, and injury litigation, and highway safety publications catalog. See our free consumer journal for automobile and road users, three subscription journals on road maintenance, engineering, and injury litigation, and a highway safety publications catalog.

Discussion of Sign Management Technologies

Traffic signs are a vital component of traffic safety. Sign management systems (SMSs) are essential for transportation agencies to maintain the millions of traffic signs in the U.S. The large number of liability lawsuits related to the condition and placement of traffic signs emphasizes the importance of sign management. Agencies are looking at new methods of sign management to increase inventory efficiency, eliminate data errors, and deal with liability issues. Systems must provide for efficiently maintaining and, when needed, replacing signs. While smaller jurisdictions may use paper-based and manually keyed systems, more populated areas require information processing and electronic technologies. The technologies applicable to sign management vary in price and capability. Various technologies can combine to meet the needs of different population areas. The last section of this summary recommends appropriate technologies for small, medium, and large agencies.

The research summarized here focused on 67 cities and 87 counties in Iowa. Descriptions of the technologies of most interest to these agencies were included in a report, "Emerging Concepts in Innovative Sign Management Programs," by Michael D. Pawlovich, Edward J. Jaselskis, and Reginald R. Souleyrette. This report appeared in the Transportation Research Board's Transportation Research Record 1553, Traffic Control Devices, Visibility, and Evaluations, published in 1996.

Elements of a Sign Management System

For each sign in an agency's jurisdiction, the sign management system must include:

installation date,
facing direction,
substrate material, and
the grade and manufacturer of reflective sheeting.

The SMS should also include:

  • a record-keeping system,
  • inspection programs (day and night),
  • reflectivity tests,
  • quality control, and
  • warehouse and field inventories.

Radio Frequency Identification

A radio frequency identification (RFID) sign management system uses tags and a reader that are linked via radio frequency (RF). Because the user can detect information, read tags, or write on tags from a distance, RFID is useful when the reader is remote, such as for signs placed in ditches.

The tags can:

  • store up to 40 bytes of data;
  • tolerate extremes of temperature, noise, and contaminants;
  • communicate bidirectionally and multidirectionally;
  • be combined with other auto ID and non-auto ID technologies; and
  • track products through production, placement, and use.

Some RFID limitations are a lack of standards among manufacturers and possible negative effects from metals and other RF-linked systems in the area. Other barriers include concerns about privacy, extended implementation time, high cost, and added efficiency causing a reduction in staff.

The cost of an RFID system ranges from $1,600 to $5,600.

Bar Coding

Bar coding contains printed information in bars and spaces of different widths and patterns. It allows quick scanning and a low rate of error compared with manual data entry. Bar code systems include:

  • scanners and decoders to read and interpret label codes,
  • symbologies, the display types for bar code bars and spaces, and
  • bar code labels and label printers.

Labels are available from distributors, or you can buy software and a printer to produce them yourself. This equipment is usually inexpensive, easy to use, and compatible with existing computer systems.

Bar code labels have limitations:

  • High print quality is necessary to produce a clear contrast between the bars and spaces.
  • Durability is a factor, as labels must remain readable when exposed to dirt and other substances.
  • An eyes-free or hands-free environment is not possible because bar codes require line-of-sight reading.

A bar-coding system costs from $1,000 to $15,000.

Video Logging

Video logging uses camera systems in a mobile unit, usually a van, to record data along a selected route. Within the vehicle are camera, control, recording, playback, and processing units. Limitations include high cost and a requirement of good visibility for recording. A video logging system, including support equipment, can cost $50,000, not including the vehicle.

Global Positioning Systems

Global positioning systems (GPSs) identify locations through ground-based receivers that use satellite signals to define the positions. These systems can replace labels to locate signs.

A standard GPS uses a receiver. For more precise (differential) positioning, the system requires a base station or a subscription to a commercial service. Data may be downloaded later into a computer for further analysis. Receiver costs range from $750 for accuracy to within 328 feet to $30,000 for accuracy to within one-fifth inch. Limitations of GPS are less accuracy (at the lower cost) and the high technology speed needed for survey quality.

Voice Recognition

Voice recognition systems convert speech into electrical signals that the computer translates into data. These systems allow eyes-free and hands-free work environments, with advantages such as increased productivity and worker satisfaction, less paperwork and keyboard input, real-time reporting, and procedure standardization.

Speaker-independent systems (allowing more than one user) are costly and may be unreliable. These systems range from $100 to $10,000. Limitations of voice- recognition systems include limited applicability and vocabulary and speaker dependency.

Optical Character Recognition

Optical character recognition (OCR) converts human-readable symbols to machine-readable code. It includes the ability to interpret images and is most useful in the area of data transfer to computers. OCR allows less human involvement and may result in more accurate data. Both humans and computers can read OCR output and can use the data with video logging to identify signs and determine their condition in real-time.

The cost of an OCR system depends on the desired camera quality and ranges from $8,000 to $40,000. Software prices vary also.

Radio Frequency Data Communications

Radio frequency data communications (RFDC) systems transmit data collected through bar codes, RFID, or other sources to a central controlling computer. RFDC allows the operator to move freely during short-range data communication. It is useful when data verification from the host computer is needed. Physical means of data transfer, such as cables, are not needed.

Advantages of an RFDC system include real-time data transfer and the elimination of paper, resulting in less data loss and fewer entry errors. RFDC allows direct communication to the home office or warehouse.

One limitation of RFDC is a need for careful system design to allow for communication between remote terminals, base stations, and the central computer. Also, the signals may be subject to interference.

Costs for an RFDC system range from $2,600 to $4,900, with base stations around $5,000. This does not include the cost of computers.

Field Computers

Three types of computers are useful in sign management.

  1. Pen-based computers allow you to take notes, keep calendars and appointments, and send and receive data, fax, and e-mail. The pen eliminates the need for a keyboard and can also draw or point to items on the screen. Designed for field use, these systems must have an adequate power supply, storage, screen resolution, and communications. They must also have handwriting recognition. Costs range from $2,000 to $4,000.

  2. Laptop (notebook) computers provide all the versatility of desktop computers but are compact and lightweight. They require a surface to rest on and both hands of the operator. Laptop costs range from $1,000 to $3,000.

  3. Handheld computers are smaller computers that fit in one hand and include a keypad, display, function keys, and various ports. Printers, modems, and bar code scanners plug into the ports. Handheld computers are sealed against dust and moisture and are designed for field applications. Costs range from $300 to $3,000.

Geographic Information Systems

A geographic information system (GIS) is a computerized database management system capable of automated mapping technology, database management, and other functions.

Vector GISs use points, lines, and polygons to represent features. A point, or node, is shown by a single coordinate location. Computers usually store signs as point features. Low-accuracy scales generally represent large land areas, and more accurate scales show detail for designers and engineers.

A GIS requires hardware, software, trained analysts, and established procedures. The system can handle only spatially related data, and startup time, data maintenance requirements, and data complexity define system needs.

Software can range from $100 for a single-purpose package to $100,000 for a package that can analyze, display, and interface with other systems. Hardware costs range from $2,500 to $50,000, excluding system maintenance.

Electronic Data Interchange

Electronic data interchange (EDI) quickly exchanges data between computers in a structured, machine-processible form. EDI requires a communication network, information guidelines, data standards, and "enabling software" for moving the data. The system can use either a PC or a mainframe.

Advantages include accuracy and error reduction, less physical data entry, faster data transmission, lower inventory-related costs, improved productivity, and reduced personnel. An EDI system allows a direct connection with the sign manufacturer to make ordering faster and more efficient.

Some EDI disadvantages include a high initial cost, the need for large volume to achieve benefit, and the impact on organizational structures and cultures.

A simple PC-based EDI system costs about $700, while a complex system will run $30,000.

Sign Management Systems

The researchers studied sign management programs of various sizes and their relationship to advanced information technologies. The following table summarizes technology needs by three agency types (small populations of less than 50,000; medium, 50,000 to 200,000; and large, more than 200,000).

Summary of Technologies by Agency Size

Agency Size Data Acquisition Data Interpretation Data Transfer Data Analysis Electronic Data Interchange
Small Bar Codes - Hand-held computer - -
Medium Bar Codes - Hand-held computer - -
Large Global Positioning
Radio Frequency
Video Logging
Voice Recognition
Optical Character Recognition
Hand-held computer
Pen-based computer
Radio Frequency Data Communications
Geographic Information Systems Electronic Data Interchange

Small transportation agencies needing to keep their costs down should choose technologies that allow inexpensive labeling and minimum hardware that may justify its cost by being multipurpose. For example, handheld computers that scan bar code labels on signs can also be used to inventory fire hydrants and traffic lights. An inspector scans the bar code and enters inspection information. Later, the information is downloaded into the sign database.

Medium-sized agencies can use the system described above with the addition of RFDC. Each handheld unit directly communicates with the central system, where it obtains the sign's maintenance history. The inspector can immediately enter necessary maintenance into the system through the handheld unit, and the system automatically generates the appropriate paperwork. The addition of voice recognition allows entering the information into the handheld computers.

Large agencies have more complex sign management needs. They may want to use a GPS to identify signs and a GIS to store sign information and verify locations. RFDC can communicate with the central computer to retrieve up-to-date data about each sign. Repair comments are recorded in the central database and are immediately accessible. When a new sign is needed, orders from the field dispatch automatically to the warehouse. EDI can order materials when needed. Voice recognition allows data entry data into handheld units.

For higher-speed inspections, such as on highways, RFID can identify signs using chips buried in the road near the signs. Information displays on the handheld unit and transmits to the central system as above. Video logging can be used with OCR to record sign features; this system would be of value to state agencies.

Copyright © 1997 by TranSafety, Inc.

Back to the Road Management Journal Index