Raising ITS Standards IQ With Implementation of NTCIP-Based Dynamic Message Signs

This Report is About:

• Using National Transportation Communications for ITS Protocol (NTCIP) standards for Dynamic Message Signs (DMSs) to develop interoperable systems using interchangeable equipment.

This Lessons Learned Report was drawn from the experiences of nine agencies (see box below) who were among the first to use Dynamic Message Signs (DMSs) built to NTCIP specifications. DMSs are also known as Changeable- or Variable Message Signs. They include a number of technologies (fiber-optic, light-emitting diode, bulb matrix, and reflective flip disk) and configurations (permanent and portable). NTCIP is a group of Intelligent Transportation Systems (ITS) standards. DMSs are a key component of traffic management and traveler information systems. DMSs were also one of the first systems to use elements of NTCIP and prove that it works.

ITS standards allow systems to talk to one another by supporting information exchange. That information is composed of data elements (the smallest unit of data), messages (a string of data elements that carry a meaning), and protocols (sets of common rules for exchanging data). ITS standards are defined for each of these information groups.

ITS standards are designed to promote interchangeability and interoperability. Interchangeability is specifically the capability to exchange devices of the same type (e.g., DMSs) from different vendors without changing the software. Interoperability is the capability to operate devices from different manufacturers or different device types, such as signal controllers and DMSs, on the same communications channel and exchange information between subsystems.

Without standards, agencies that deploy ITS may be locked into proprietary specifications, custom interfaces, reduced options for vendor competition and price stability, early obsolescence, and a need for unique training and specialized skills. Moreover, most current ITS deployments will have limited interchangeability and interoperability. Without standards, you have two choices in expanding your system: buy the same brand of equipment, or re-design/re-build your system. And as seen in other industries, the long-term costs of operating and maintaining proprietary technology is higher than for technology based on open standards.

Agencies Responding To The NTCIP / DMS Survey:

• Arizona DOT
• Delaware DOT
• Illinois State Toll Highway Authority (ISTHA)
• Minnesota DOT
• New York State DOT
• New York State Thruway Authority
• Pennsylvania DOT
• Virginia DOT
• Washington State DOT

Use of standards can help avoid disadvantages created by procuring custom DMS solutions. Operation of a DMS requires a communications protocol—a set of rules for coding and transmitting messages between electronic devices. With the support of the USDOT, standards development organization (SDO) committees developed a comprehensive set of ITS standards in order to standardize the way transportation systems exchange data. Among these is a group of standards known as the National Transportation Communications for ITS Protocol (or NTCIP). Specifically, NTCIP standard 1203 was developed for deploying DMSs.

Standardized message sets format the data sent to the DMS. Interchangeability and interoperability—a goal of the ITS community and the National ITS Architecture—can be achieved if all DMSs recognize the same data elements in the same format or structure.

The National ITS Architecture provides a framework to help:

• Identify key stakeholders and their relationships
• Describe required activities or functions
• Define interconnections and interdependencies between functions
• Define a blueprint for integration of systems

In September and October 2000, personnel from nine transportation agencies responded to a comprehensive questionnaire about lessons learned during their implementation of NTCIP-based DMSs. The nine agencies had implemented nearly 60 DMSs, with nearly 80 others in process or planned; altogether, these DMSs represented five manufacturers.

The questionnaire solicited information about experiences and observations concerning DMS procurement, installation, and operational stages. As the agencies answered the questionnaire, their DMSs were in different stages of completion—installation in progress, in acceptance or operational testing, or in full use.

The agencies decided to use NTCIP standards for DMS implementation for several reasons:

• Ease of integration and interoperability
• Elimination of software compatibility issues during implementation
• Avoidance of proprietary software issues (particularly with multiple vendors)
• A desire to be proactive and in the forefront of standards compliance
• Recognition that standards are encouraged for Federally funded ITS projects.

The survey demonstrated that diverse experiences resulted from implementing ITS standards in DMSs. The degree of ease in using the NTCIP standards for deploying DMSs also varied. Some agencies were clear that the standards helped them achieve interchangeability and/or interoperability, though most used some type of qualifying remarks in that regard. However, most agreed that the impact of standards on their final DMSs was both positive and a good decision.

Overall, participating agencies realized significant benefits. Achieving interchangeability and interoperability was the major incentive to use standards. Most respondents agreed that the use of standards allowed them to get more benefits than with the typical custom procurements.

Respondents also commented on the benefits they expect to realize when future system enhancements and maintenance are needed. For example, standards help system enhancements to be transferable among different sites. Also, system maintenance and life cycle costs should be more affordable. In time, engineers will be able to maintain standards-based systems more easily because they will be familiar with the operations used consistently in the systems. Thus, engineering staff will not have to be retrained to work on a new system.

The participants recognized that they will have a larger choice of vendors as standards mature. The resultant expanded competition will keep prices down and provide options. Also, the standards will enable them to use non-proprietary software and help achieve interoperability.

Use of draft standards can cause problems. Three of the agencies issued an RFP based on draft standards, but were disrupted by software changes and inconsistencies resulting from changes to the standard. These respondents felt that NTCIP standards were slow to mature. For example, when one agency added a second vendor, they had to make software modifications; they felt this was due partly to the use of draft standards and partly to deficiencies or vagueness in the current published standard.

Specifying NTCIP alone is not adequate. An agency must further define its requirements, specifying the required and optional parts of a standard in detail during procurement. There are payoffs when an agency understands what it needs and properly specifies its standards requirements in its procurements.

Other problems the agencies noted include:

• Difficulty and expense associated with getting the references in the NTCIP Guide (i.e., would have been helpful to have a summary of all the NTCIP references)
• The need to rely heavily on available consultants because of scarce in-house expertise
• The impact of basic unfamiliarity with standards upon deployment and subsequent maintenance

The following advice is offered to future deployers of NTCIP-based DMSs:

• Use NTCIP standards to take a big step toward obtaining interchangeability and interoperability for DMS. Standards help you select from a larger choice of DMS vendors and avoid using proprietary software.
• During procurement, build on what others have learned to help you get just what you need.
• It is wise to obtain references on DMS vendors. Use of vendors who already have installed NTCIP-based DMSs reduces risk. Research several DMS manufacturers and ask for their NTCIP specifications and timeframe for installation before selection.
• Access to expertise in specification writing and testing is crucial. If you do not have experience with NTCIP and DMS communications, hire someone who does.
• It is helpful to have a tight RFP - one that is very specific about DMS communications (i.e., the computer “vocabulary” and the management and control of data) and other ITS standards that apply to the project.
• Make sure you specify in the RFP, not just NTCIP but the exact standards—and even the DMS and global objects—you want. In particular, be very specific about communications planned for the signs, and lay out specifications for fiber, phone lines, and data exchange rates.
• Consider using a weighted RFP that allocates points for standards use, functionality, manufacturer’s experience, warranty, price, and documentation.
• Specifications should call for just the standards and data message sets needed to support the proposed system. If you follow a blanket approach of specifying all standards and data message sets, the development cost will increase greatly due to software that will not be used.
• Give specific information about the capabilities to be provided and indicate that a test procedure to demonstrate the capabilities needs to be identified, developed, and approved by the client.
• Ensure that the software is compatible with the operating system used by each component.
• Get a warranty that covers firmware and software from the vendor.
• Consider placing firmware and software code in trust; you will then have a guarantee that if the owner becomes unavailable, another vendor can work on the code and use it in the future.
• Try to devise a solution that minimizes the use of custom message sets.
• Document in great detail all vendor-specific data message sets and vendor and integrator software.
• If multiple agencies are involved, make sure they are communicating during the development of data message sets.
• Make sure the vendor will provide assistance at an appropriate level during any testing.
• Try to use the NTCIP Exerciser to test DMSs. Access the Exerciser at www.ntcip.org/library/software.
• Finally – and extremely important - don’t assume that best price is the solution! Incorporating standards is an investment in the future.

The primary ITS standard tested by the agencies was a device object definition standard: National Transportation Communications for ITS Protocol (NTCIP) - Object Definitions for Dynamic Message Signs (DMS) (NTCIP 1203, formerly NEMA TS 3.6-1997).

Secondary NTCIP communications standards or device object definitions tested by some of the agencies include:

• Simple Transportation Management Framework (STMF)(NTCIP 1101, formerly NEMA TS 3.2-1996)
• Class B Profile (NTCIP 2001, formerly NEMA TS 3.3-1996)
• Global Object Definitions (NTCIP 1201, formerly NEMA TS 3.4-1996)
• Point-to-Multi-Point Protocol Using RS-232 Subnetwork Profile (NTCIP 2101, formerly NEMA TS 3.PMP232)
• Simple Transportation Management Framework (STMF)– Application Profile (NTCIP 2301).