U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
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A number of forces have driven the creation of the Pavement Marking Management System (PMMS) and are ensuring its continued existence. The PMMS system in essence provides a pool of data that can be developed and deployed to resolve complex problems facing transportation agencies. The Pavement Marking Management System is information technology, which can be viewed as putting in place a system that will allow its users to make data driven decisions.
Information technology applications are enabling agencies to reduce cost through improved operating efficiency. Some systems were not considered key elements, which was especially true for pavement markings, until the passage of the appropriations act of 1993 (i.e., the ISTEA bill). One of the central parts of ISTEA, which is aimed at improving highway safety, is the establishment of a minimum value for pavement marking retroreflectivity.
Pavement markings play an essential role in the safe and efficient movement of traffic, especially during hours of darkness. It is a well-known fact that in order for pavement markings to be seen at night they must be retroreflective. Glass beads, which are imbedded into the marking material, make pavement markings retroreflective. Retroreflectivity is the technical term used when describing how a vehicle headlight illuminates a pavement marking. It is technically wrong to describe pavement markings as being “bright,” but for simplicity this term will be used in this manual.
One of the original driving forces behind the development of PMMS is the Federal Highway Administration (FHWA) legislative mandate to set minimum retroreflective values for pavement markings. With this in mind, responsible agencies are stepping up efforts to develop new processes so that minimum values can be maintained.
The Minnesota Department of Transportation, with the help of FHWA, jointly developed this system. The aim was to develop a comprehensive system that will track the useful life of pavement markings. PMMS will track all of the following:
At this time, there is no standard/guideline for minimum retroreflectivity values on public roads. However, FHWA is expecting to start the rule-making process to establish threshold values in 1999. In the next update to the Manual on Uniform Traffic Control Devices, FHWA will provide pavement marking retroreflectivity guidance. Although no such guidance currently exists, many transportation agencies have for some time focused efforts toward reducing the loss of visibility of pavement markings during the hours of darkness.
Special instruments (i.e., retroreflectometers) are needed to collect pavement-marking retroreflectivity. They are used to determine how bright the markings appear at night to motorists. All reflectometers are designed to read pavement markings within specified geometric ranges. FHWA has determined that 30-meter geometry replicates typical driving experiences and has adopted it for their rule-making processes. This geometry conforms to what an average passenger automobile driver sees when viewing 30 meters ahead of the vehicle at night. Various manufacturers are producing a wide range of both handheld and mobile retroreflectometers. Handheld reflectometers are used by placing the meter over markings at specified intervals. Once the total number of handheld readings at each interval is collected and averaged, an entire segment average is determined. Mobile instruments measure retroreflectivity of pavement markings while driving at highway speeds. An onboard computer is responsible for collecting and analyzing the retroreflectivity data. No matter which instrument is used, an averaging of all the readings taken over a specified segment length should be done. Averaging the measurements, whether mobile or handheld, normalizes the variability present in all markings.
The industry’s collective understanding of how pavement markings function has grown exponentially over the past 10 years. And, with the advent of various pavement marking management systems the ability to actively manage pavement markings is adding to responsible agencies cornucopia of managerial tools.
In order to effectively manage pavement markings, agencies must have complete information about their pavement marking installations. This could be considered the hear-l of this system. To make data driven pavement-marking decisions managers need complete installation information. With this type of information, managers/supervisors can identify problem areas, determine maintenance schedules, and effectively plan budgets.
In order for this level of decision-making to be possible, processes that track complete and accurate installations must be incorporated. Critical components that should be tracked include location, date, specific line, material type, and quantity of material used at time of installation. The location should track from reference point to reference point, or some such common beginning and end points, where the markings were installed. Each line (e.g., centerline, edgeline, lane line, etc.) should be tracked by installation date. Material type indicates what type of line was installed. Some of the most common types are latex, tape, thermoplastic, or epoxy. Many agencies will call for multiple material types within the same locations, which is not a problem for PMMS. Example, agencies will specify tape for the lane lines (skips) and will use epoxy for the edgelines. Again, PMMS is capable of tracking multiple material installations. Tracking materials is one of the foundations that this system was designed to track.
Many of the decision options that PMMS can provide depend on accurately tracking pavement-marking installations. Without this type of process, developing an inventory could be very expensive. PMMS approaches this by tracking daily installations. This is one of the principle reasons that both maintenance and contracted input screens were developed. One major problem with tracking any inventory is that the database (i.e., the inventory) is usually out of date by the time it is entered into a data base. PMMS inventory will never be out of date if markings are tracked as they are installed.
If pavement markings are to be seen at night they must be retroreflective. Retroreflectivity refers to the principle of light being directly returned to its source. In automobiles the light source is the headlight of the vehicle. Again, special instruments that have been designed to read at a specific geometry measure this light intensity. A central part of PMMS is the requirement that field inspection for retroreflectivity be completed.
The type of reflectometer used to measure markings does not matter. Agencies will specify the process for field inspections, and the Manual on Uniform Traffic Control Devices (MUTCD) will provide guidance on retroreflectivity values and reflectometer geometry. Many of these factors will vary from region to region and State to State. A central focus of PMMS is the ability to track pavement markings so that the various pavement marking’s life cycles can be determined.
Collecting retroreflactivity with either mobile or handheld meters can be time consuming and expensive. Before determining which process to use agencies should consider:
PMMS is designed to allow inspectors to collect retroreflectivity data and store it in tables for future reference.
Once life cycles can be established for each type of marking used, the responsible agency will have many options. The ability to determine when or how often markings are in need of maintenance is first and foremost. PMMS will give an agency the ability to record specific action steps. In addition to enabling effective maintenance, PMMS offers agencies the following benefits.
These benefits cannot be gained without timely, efficient, and comprehensive recording practices. The memo field in either the maintenance or construction daily log offers agencies the opportunity to record and store this information. Agencies should consider including some of the following in the memo field.
It is more important today than ever to have the ability to track costs. PMMS is designed to provide agencies/authorities with the data they need to manage striping costs. It makes sense to replace only pavement markings that need replacement, or in other words, only markings that are at the end of their useful life. Pavement markings themselves are only one part of the cost equation. PMMS allows agencies the opportunity to track employee, equipment, and material costs, which are key parts of developing pavement-marking cost.
Tracking suppliers, and more specifically, material batch numbers, can answer many questions when problem installations are uncovered. Past experience has shown that failures can be tracked to specific batches of material. An advantage of tracking areas in this detail becomes clear when you can uncover other areas with the same material that may also reveal a failure.
This is exactly the type of information that managers/supervisors need when determining system needs. Another use for such information is to compare suppliers against one another. This type of information can lead to quality improvement in an overall pavement marking program.
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