U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
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After understanding the different ID methods, transportation agencies may consider several issues when selecting the appropriate ID methods for their network. This report identifies six primary performance issues regarding deployment of the ID methods identified:
Cost is also a factor for agencies to consider alongside performance.
There are two concepts that can be used to identify roadside safety hardware: hardware as a system of components and the individual components that make up that hardware. For example, a guardrail system would include railings, posts, block-outs, and end treatments. An individual component would include the end treatment alone (even end treatments could be further broken down into separate exchangeable components).
These concepts were developed assuming that manufacturers would not install tags. However, some manufacturers are already positioning themselves, or being required, to have the ability to identify their products.(38)
Based on the hardware as a system concept, transportation agencies would need to place only one tag for the entire hardware system or could even place the tag in the physical location of the system, not on the system components themselves. In the case of the individual components concept, agencies might have to install multiple tags at each location and sync or code those tags to the same unique ID number or numbers for each priority component of the hardware system. A third identification option blends the two by considering each piece of hardware as a parent of child components.
In the hardware as a system or location-based option, transportation agencies will tag hardware locations and include component and installation information in a documentation database. There will be one data key at each roadside safety hardware location. The agency will either be required to input manufacturer and installation information or provide manufacturers and installers access so that they may input this information. The documented information will provide the agencies with the ability to analyze both the hardware as a system and component data by location, installer, and manufacturer. This option relies heavily on the transportation agency and installers to correctly and diligently input information at the time of installation, at the time of repair and maintenance activities, and at the time of replacement.
In the component-based option, transportation agencies will tag each priority component and require manufacturers or installers to tag new or replacement individual components of hardware. The agencies will be able to analyze the performance of individual components but may have difficulty understanding the performance of the series of components. This option will create multiple unique identifiers at each installation location, and when maintenance staff or an installer repairs or replaces a component, these new components will most likely have new unique identifiers. It is also important for transportation agencies to consider what to do with the tag of an obsolete component. Using a kill password to render an RFID useless or obliterating the barcode or serial number might help to prevent obsolete inventory from being included in a current database. This option relies heavily on the transportation agency to maintain and frequently update a detailed database, including a large number of components.
A logical blending of the hardware as a system and hardware components tagging options is to view each piece of hardware as a parent of child components. For example, a guardrail parent hardware has an end treatment child component. This option would allow agencies to tag the parent hardware as a system or location and then attach child ID numbers to priority components. Transportation agencies can generate child component identifiers for existing installations and/or assimilate manufacturer identifiers under the parent hardware.
This option may also provide a mechanism for the transition from no identification and documentation by allowing the transportation agency to take small steps. Agencies would only have to identify existing parent hardware as systems while designing or moving toward the deployment of an identification and documentation program around new installation, maintenance, and repair. The documented information would provide the agencies with the ability to analyze both hardware as a system and hardware component data by location, installer, and manufacturer. This option would also allow for the industry to standardize manufacturer and installer information, making it uniform across all agency databases.
It is important to consider the scale of implementation. For example, a typical urban freeway may have hundreds of installations of roadside safety hardware per mile. Even a rural local road is likely to have a few dozen. Based on the potentially large number of roadside safety hardware installations that an agency may have, a roadside safety hardware tagging effort may be a significant undertaking. Furthermore, agencies may find themselves with a mix of untagged components and tagged replacement components. Agencies that adopt the concept of hardware as a system may find locations with tags from newly manufactured components (with non-uniform and different ID information), and transportation agencies that adopt the concept of hardware by components may find it difficult to tag all existing installations.
Manufacturers, installers, and/or transportation agencies must consider where to install the tag identifiers and whether placement would bring attention from potential vandals who might destroy or deface the tags. This is especially important to consider when determining whether transportation agencies should install serial numbers and/or barcodes. If vandals were to deface these types of tags and the destroyed/defaced tag was the only carrier of information, the transportation agency would lose all the information associated with the tag.
Although tag placement may affect the potential for vandalism, it will also impact the ability of the transportation agency's staff to read the tags, including using mobile data collection techniques. For example, if the installer places a tag in a location on the hardware where a component obstructs it from view, transportation agency staff would have to exit a vehicle to scan the tag.
To deal with these issues, transportation agencies could use the following placement options to combat vandalism:
A primary issue of concern is whether tag identifiers can withstand roadside conditions. Roadside conditions consist of many environmental, maintenance, and crash events that could impact tag operation and durability. Determining whether tag manufacturers had considered these types of conditions and had developed hardened tags was critical in evaluating the potential success of tag deployment.
The equipment specifications collected provide information for hardened/outdoor tags including 31 RFID tags and 36 barcode/serial number tags. Additional roadside conditions of interest should be considered such as maximum and minimum temperatures and common roadside chemicals.
Understanding the expected regional temperatures that the tags will be exposed to will assist in determining the durability of available tags. Record temperatures in the United States range from -62°C (-80°F) in Alaska on January 23, 1971, to 57°C (134°F) in California on July 10, 1913.(40) High pavement temperatures may also impact temperatures at installations on roadside equipment.
Commercially available RFID tags can operate in extreme cold down to -50°C (-58°F) and extreme heat up to 300°C (572°F).(41) The ability to handle extreme temperatures varies greatly based on the encasement materials used for an RFID product. Plastics, resins, and metals have all performed well.
Commercially available barcode/serial number tags can operate in extreme cold down to -54°C (-65°F) and extreme heat up to 648°C (1,198°F).(42, 43, 44) For barcodes, not all manufacturers' specifications list a minimum operating temperature.
Transportation agencies must consider the impact of moisture for any tag option. Almost all roadside safety hardware is exposed to humidity and precipitation, including rain, snow and ice, as well as longitudinal barriers installed near waterways and drainage. Transportation agencies will need tags to withstand these conditions and periodic submersion from flooding and/or snow. Additionally, transportation agencies with facilities near coastlines should consider coastal spray and the need for saltwater resistance.
Water-resistant and submersion options are available for both RFID and barcode/serial number tags. For example, 28 of the available 31 durable RFID tag specifications list the product as submersible. For available barcode options, not all specifications indicated the ability for users to submerge tags but rather listed exterior exposure data to meet Federal Specification GGâ€‘Pâ€‘455B from the mid-1960s for plates and foils. The Federal specification requires testing within a weatherometer but never indicates specific water resistance values or submersion, although the specification requires numerous chemical and organic solvent resistance values.(45) Moisture-resistant options are available for all conditions and for all tag types.
The sun will impact any installed tag through ultraviolet (UV) light. This exposure can cause certain materials to break down. Transportation agencies should consider UV-resistant tags to prevent degradation of visual-based tag information on barcodes/serial numbers, and degradation of the material for both RFID and barcodes/serial numbers.
Tags with significant UV resistance or imperviousness to UV exposure are commercially available. One barcode/serial number tag option includes a ceramic-fused stainless steel alloy with up to 100 years of UV resistance.(43) Tag options for RFID also include materials that are impervious to the impacts of UV light. However, transportation agencies should be aware that some tags do not have significant resistance to the impacts of UV light. Many RFID manufacturers claim their tags have excellent UV resistance but do not indicate how many years of resistance that covers. Some of the barcode/serial number tag specifications simply list a value for outdoor exposure length ranging from 1 to 10 years.(46)
In desert areas with high winds, transportation agencies should consider the potential for tags to suffer from abrasion due to particulate impact.
Abrasion-resistant options are available specifically for barcode/serial number tags with specific brush and abrasion wheel testing results. Some barcode/serial number manufacturers claim unparalleled abrasion resistance.(46) In contrast, most RFID tag specifications do not specifically address abrasion resistance. This could be primarily due to tags not having information printed on the outside of the RFID tag. Any abrasion concerns for RFID-only tags would ultimately be about particulates penetrating the encasement material.
Common chemicals found near safety hardware include de-icing and anti-icing chemicals, herbicides, and petroleum-based chemicals such as diesel fuel and motor oil. Transportation agencies should consider using tags installed on roadside safety hardware that are resistant to saltwater, various herbicides, magnesium chloride, calcium chloride, diesel fuel, and motor oils.(47, 48, 49)
Chemical-resistant barcode and RFID tags are commercially available. These chemicals include solvents, acids, alcohols, ammonia, bleach, brake fluid, caustics, cleaners, engine coolant, chlorides, Freon, fuels (diesel, jet, and gasoline), heptane, hexane, hydrocarbons, ketones, oil, saltwater, sodium hydroxide, transmission fluid, xylene, and xylol.
Transportation agencies should deploy tags that are resistant to staining and smearing, especially for visual-based tags such as barcodes and serial numbers. Tags should also resist overspray from paints and pavement maintenance activities. Since RFID tags do not rely on visual performance, staining and smearing are of no consequence unless combined with a barcode surface tag.
Many barcode/serial number tag options have staining and smearing resistance. One particular manufacturer coats barcode/serial number tags in Teflon, making the tags resistant to cleaning, pickling, painting, and powder coating.(50)
Agencies need to consider whether to put detailed hardware information on the tag identifier or use the identifier as a data key to access the information in the database. There are two primary ways tag readers convey information:
Similarly, security threats can include back-end and front-end security threats.
Back-end security threats include unauthorized access to the database or network server. This could be via an unauthorized tag reader or user via an internet connection to the information database. Unauthorized readers, hackers, and vandals have the highest potential to create back-end security threats.
Front-end security concerns include:
Transportation agencies have three primary security options:
In this case, the transportation agency would deploy no security options, allowing tag identifiers to be both read-only and read-writable without access authorization protocols. This option allows multiple organizations easy access to read and write hardware and event information on either the tag or the transportation agency's database.
This option creates the potential for abuse from private citizens and/or vandals, allowing unwanted users to access, read, and input information. This security option would also prevent any capability for the transportation agency to track the ID of database users. Transportation agencies could limit their exposure by installing tags holding only a data key or ID number and requiring users to know the address of the agency's database to access information.
In perhaps the most secure option, the transportation agency would deploy back-end database access security, allowing only authorized readers direct access via middleware to the database using current, proven security practices. For example, a secure socket layer is a standard security technology for establishing an encrypted link between a server and browser, or reader in this case.(52) If the transportation agency provides access to users via the internet or enterprise software with internet interface, the agency could deploy username and password security.
Authorized users would then access specific hardware information using the hardware's unique identifier by scan, read, or manual entry. This option would allow the transportation agencies to assign multiple levels of access, roles, and permissions to the database. In addition, transportation agencies could track both database inquiries and any information entered into the database according to the user, time, and date the information was inputted.
This option would also allow for using read-only tags, a recommended security best practice along with excluding confidential information on any tag.(51) This option is also potentially tag agnostic, only requiring a data key/ID number.
For RFID technology, Gen2 RFID Standards provide for the ability to lock the information on the tag, but it is unclear if there are any direct access permission protocols to prevent an unauthorized reader from reading the information on an RFID tag. There are multiple built-in features including a lock memory and kill password:
Additionally, transportation agencies could deploy encrypted serial numbers on the tags, but this may complicate data flow and would require a management process for the encryption key.(51) For barcodes, one option is for agencies to encrypt 2D barcodes since research suggests this strategy as a transit ticket security solution.(54)
Members of the expert panel noted the potential need for tags to be able to withstand direct vehicle impact. It is difficult to determine the importance of this need without knowing where transportation agencies and the industry will place tags, presumably by a future standard, and how the tags will be attached. If transportation agencies place tags on hardware where they could potentially receive a direct impact from a vehicle, the force and scraping of the vehicle across a tag could compromise the integrity of both visual readability for barcodes/serial numbers and RFID chip operation. If transportation agencies place tags on secondary components, such as a strong post for a guardrail system, the means of attachment becomes vital so that the force from vehicle impact does not dislodge the tag from the roadside safety hardware.
Some manufacturers test tags for impact and pressure. One RFID manufacturer tested tags by dropping an 18-kg weight from a height of 2 m, which provides some impact resistance data but does not replicate the impacts expected in a vehicle crash, and the tag still functioned after more than 25 drop tests. The manufacturer also pressure-tested the same tag under 30,000 pounds per square inch for 30 days.(55)
The way an agency attaches tags could be just as important as direct impact during a crash event. There are many potential ways transportation agencies, manufacturers, and installers can attach tags, including adhesives, cable ties (or a similar system), embedment, rivets, screws, tethers (or a similar system), and welds. However, if the force of the vehicular impact dislodges a tag, it is important for transportation agencies to be able to locate the dislodged tag. Due to line-of-sight restrictions with barcode/serial number tags, this type of tag would have to be located manually. If the agency were to use an RFID reader with a tag locator mode, agency staff could use the reader to locate a dislodged RFID tag.(56)
One of the overarching evaluation categories is the ability for tag identifiers as an ID method to connect and exchange information with existing asset management databases and software. An important characteristic transportation agencies should be concerned with involves associating unique identifiers with existing unique assets. One of the major components of an RFID and/or barcode system is the middleware that affords the connection to an existing server database or enterprise software. There should be no barriers to connectivity via middleware. Typically, middleware is pre-installed on the reader and can be set up to connect to existing systems. Costs may be associated with installation, operations, maintenance, and training with using the system, but these costs should be minimal.
When selecting hardware ID methods, transportation agencies will need to decide whether to tag the system or the individual components; how detailed the information on the tag will be and how to secure the information; where on the roadside hardware the tag will be placed to balance usefulness, durability, and potential vandalism; and the middleware needed to connect the unique assets with existing agency data systems. The next chapter describes the evaluation approach for the various ID methods that transportation agencies could use for identifying roadway safety hardware.
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