Chapter 4. Developing the Telecommunication System
Telecommunication systems can be very complex and difficult to design because there is usually more than one way to meet requirements. Often, several communication protocols must be used in the final design. This chapter attempts to provide the traffic engineer, and traffic system project manager, with a suggested process for developing the design and specification for a communications network to support traffic signal and freeway management systems. A theme that is repeated throughout this handbook is that the design of a communications network to support roadway and transportation functions is not a stand-alone process. The determination of functionality and selection of options must be done as an integrated part of the overall traffic management system design. Personnel responsible for the development of the communications system should be full members of the overall project team.
Central to the development of the communication system is the fact that it is there to serve the requirements of the overall project. Communication project personnel should attend general project planning meetings. If new roadway construction, or roadway modification, is part of the overall project, communication engineers should be included.
This chapter is organized into six primary sections. First, a recommendation of qualifications for a telecommunications consultant, including types of experience and education. The next three sections are devoted to the Requirements Document. The development of a complete requirements document is essential to the proper implementation of a telecommunications system. The final section concludes this chapter with some basic recommendations for managing the communication project.
This section provides guidelines for selecting an engineering / communications consultant with the right qualifications. Three basic qualification areas must be considered when selecting a qualified communication consultant: experience, education, project background. And, these four (4) basic rules apply in making the selection:
There's no substitute for experience.
Qualified applicants need to demonstrate a good understanding of how each element of a communication system will impact on the viability of a whole system. There are only a few engineering schools offering degree programs in telecommunications. Technology changes faster than the professors can write new text books.
Communication Engineers don't design traffic (or freeway management) systems don't use a traffic engineer to design a communication network.
There's no substitute for experience. Consulting firms (or individuals) should have at least 10 years (as individuals or combined with other team members) of experience in analysis, design and implementation of communications systems. Ten years may seem like a very heavy requirement, but will assure that the engineer (or firm) will have a broad range and depth of experiences. Most communication system engineers are used to the idea of wearing many hats. And, as technology changes, there is a greater need to have a broad application experience than a specific focus. There is also a need to understand legacy technologies. In many circumstances, the communication engineer must design a system that allows for the use of legacy technology, adds current technologies, and provides for implementation of future technologies.
During the course of writing this handbook, more than a dozen new IEEE standards relating to Ethernet and the application of Ethernet to wireless and broadband wireless were either published, or sent to committees for final acceptance, and there are about a dozen more in development. Since the early-1990s there has been a focus – by the telecommunication carriers – to move from primary support of analog voice based services to data transmission services. During that same period, Transportation agencies – on a broad scale – embraced the use of technology to support their operations. Their use of telecommunication technologies has very rapidly evolved from analog systems to digital data systems and the use of wireless. There is a general convergence of voice based and data based telecommunications services. This creates a greater need for communication engineers to develop a broad based background. During the transition period, it is important for telecommunication system designers to have an understanding of both analog and digital communication systems.
Different Telecommunication Design Specialties
Many specialties have engineers that primarily do design and others that focus on construction or manufacturing. The same is true for telecommunications. There are engineers that only do design and those that work on the construction of the systems. For most ITS projects it's a good idea to have at least one member of the design team that has experience in both the design and implementation of communication systems. Most communication system designers have learned valuable lessons by actually having to make their design work. Larger firms may have significant breadth of experience in developing traffic signal and freeway management systems. However, you'll want to look closely at their experience with communications systems design and deployment. If you are making a choice between two or more qualified firms, take a hard look at both corporate and individual personnel experience.
Many IT personnel have significant experience with the deployment of Local Area Networks, but the may lack a background with the types of systems required for freeway management and traffic signals. Local area networks are generally deployed within a building. The personnel designing those systems don't have to worry about location of the media infrastructure, or bringing power to a communications cabinet, or using equipment that can survive extremes of temperature and moisture. On the other hand, make certain that an experienced IT person is involved in design of the control center.
Types of Telecommunications Experience
Communication system engineers should have the following experience (this can be defined as either direct experience or the management of individuals and firms doing the work):
- Construction: Direct burial; conduit design; pole mounting of cable; towers and roof mounting of antennas for radio systems.
- Equipment installation: multiplexers (analog, digital, and fiber optic); modems; DSU/CSU; routers; switches.
- System Design: VF (voice frequency); Digital (T-1/T-3, Compressed Video); Fiber Optic (SONET, ATM, Video); Wireless; Ethernet, Video Over IP (VIP); Voice over IP (VoIP).
- Experience in creating alternatives analysis to provide several options for meeting requirements.
- Design and deployment of communications systems for traffic and transportation purposes. Very important – a communication engineer with no concept of traffic and transportation systems won't understand what the communication system has to support.
- The project background of a communication consulting engineer is important. Projects denote experience.
- Overall project experience should be a combination of general communications systems design and deployment as well as specific.
- Look for projects that relate to the objectives of the current project.
- Any other relevant experience that directly relates to the specific project.
Knowledge of Telecommunications Systems Relationships
Seek out engineering talent with a good understanding of how each element of the communication system will impact on the viability of the whole system. The following should be applied in the search for qualified firms and personnel:
- There is almost never a situation in which one type of communication system (or element) will provide a solution for all system requirements. Very few communications systems use only one type of technology – look for personnel with a variety of system design and deployment experience.
- Most systems use combinations of technologies. An existing large traffic signal control system may use twisted copper pair connections between local controllers and field masters, and a fiber connection between the field masters and the central computer. The local DOT may have decided to upgrade the system by adding intersections and using wireless for the new communication links. The new communication system may also have to be capable of adding CCTV and traveler information signs. The communication engineer responsible for completing the design should have experience with all of the proposed equipment, the legacy equipment, and the necessary communication protocols.
- An experienced communication system engineer will understand how all of the elements can be made to work together. Traffic engineers may have significant experience with the legacy portion of the system, but won't understand how to integrate with the fiber and possibly Ethernet and broadband wireless systems. System designers lacking sufficient experience and education in only one piece of the communication requirements for the above system will probably make a mistake and there will be a need to spend additional money to correct the problem.
- An experienced communications engineer will ask questions. They will want to know how the traffic signal or freeway management system is supposed to work and the communication needs of each element of the system before creating a design. When working with a communications engineer, tell them what you want the communication system to provide, not the type of technology required.
Education is important, however, there are only a few Universities offering degree programs for communication system design and/or engineering. Most engineering schools offer courses in communication technology. However, the courses are designed to provide the student with a fundamental understanding of how the technologies work. Additional points:
- Universities can't make curriculum changes that keep pace with the changes in communications technology. The implementation of new technologies is occurring within a short time frame after their invention. Coincidently, universities are at the forefront of both the development of new communication technologies and their immediate implementation.
- Universities offer courses in communication technologies to provide students with knowledge that will assist in the design of communication hardware. These courses are normally associated with the Electrical Engineering program.
- Many universities offer management level course work in telecommunications technology, but these are generally focused on the economic aspects, and strategies for their use. The Rochester Institute of Technology, Rochester, New York, offers Undergraduate and Graduate degree programs in the field of Telecommunications. The school also offers several certificate programs. More information is available at http://www.rit.edu.
- There are no Professional Engineering licenses for Communication Engineers. The Electrical P.E. license exams don't cover telecommunications.
- An individual with an Electrical Engineering Degree and a PE is not necessarily a communications engineer. However, an individual with a Civil Engineering Degree, a PE and 5 to 10 years of experience in the construction of communication networks should be heavily involved in both the design and deployment of communications infrastructure.
- Many qualified communication engineers have a Bachelors, or Masters Degree, in a non-engineering field. However, their qualification for communication system design was learned on the job. Many have attended technical courses provided by equipment manufacturers or professional development companies. Taking these professional courses or seminars is a good way to keep "current" on new communication technologies.
- Many Community Colleges offer Associate Degree Programs in communication and technology engineering. These programs generally focus on the construction of telecommunication infrastructure, the installation of media and use of test equipment.
- The Armed Forces offer excellent training programs and an opportunity to design and implement telecommunication systems. Many individuals working in telecommunications have been through these programs. There's a lot of good experience gained by installing, operating and maintaining a telecommunications network in a combat area.
The communication system requirements document is based on the overall concept of operations for the traffic/transportation system. Keep in mind that the communication system is a supporting element of the overall system. It is important for the project team to make certain that the communication engineer is fully aware of the concept of operations for the main project.
The requirements analysis sets the tone for the whole project. Organizing the requirements analysis into primary elements will help the project team visualize the interactive relationships. The organization chart (figure 4-1) is a suggested representation of one method of creating the visualization. The reader may have another preferred way to show the relationships. There is no "right" or "wrong" way to present the information. Simply be aware that creating a requirements analysis for the communications system starts with the overall program requirements analysis.
Figure 4-2 shows the relationships of the major functional elements of a proposed system and the general communication link required. In chapter 3 we looked at how the national architecture is used to structure a relationship between various elements of a freeway management system. The requirements analysis is the process for telling systems designers what system functionality is needed. If the whole project was laid out in a block diagram, figure 4-2 would represent one portion of the overall diagram. This diagram represents the communication links for the field equipment.
Once the role of the communication system – in terms of the overall program – is established, the communication engineer should focus on developing this aspect of the requirements document. Following is an example of a communications system centric requirements relationship diagram:
The chart is generic. There is no attempt to specify technology only general requirements. Communication technology strategy is determined by examination of the specific system requirements. The communication system is one of the operational elements of the Incident Management System. The chart shows the relationship of communications systems to the whole project and individual elements. The design engineer will be forced to explain all of the links and not overlook any requirements.
The "Gee-Whiz" Factor
It is important to approach the communications system design with the right attitude. There is a tendency to look at the "gee-whiz" of communications technologies and assume they will support project requirements. Project managers and engineers should get past this phase of the requirements analysis as quickly as possible. Streaming Video over an IP Multi-cast network is not the only solution to provide for the distribution of video. The communications systems are designed, and implemented, in support of the traffic management system – not vice-versa!
However, there is a valid reason for using the "gee-whiz" factor. Properly employed, it can lead to some innovative uses of technology. An example of the innovative use (within the transportation environment) is presented in Chapter 7. The project team should look at the "if anything is possible" scenario. It is perfectly acceptable to ask the communication engineer to look at system options using leading (sometimes called "bleeding") edge technology. The communication engineer gains an understanding of project team expectations. In return, the project team is provided with enough information to make the right decisions.
Completing the requirements analysis will provide the project development team with a clear understanding of the viable alternatives, the role of the communication system as part of the overall project and a potential budget for the communication system.
The communication requirements analysis should be completed as a part of the overall project concept of operations and requirements analysis. When practical, wait until the project requirements analysis is almost complete. The communication system is there to serve the needs of the overall traffic/transportation system.
Keep expectations realistic – ask questions
- Does the system have to be up and running 99.999% ("five nines") of the time? Does the added cost and complexity make sense considering that a "five nines" tolerance is the equivalent of 315.36 seconds (or 5.256 minutes) per year of outage?
- Is QoS (Quality of Service) really an issue or is that just the Ethernet/ATM/SONET account manager talking? Constant monitoring of all system elements is more expensive to implement than a simple ability to locate problems.
- Are there different requirements for each link and each device in the system? Don't let one element of the system create problems for all of the other elements. Compromise will be necessary.
- Is specification of end to end system latency of 1ms realistic? Consider a video system with PTZ. For the PTZ control a specification of 1ms latency may seem reasonable. However, a codec that delays the image by 2 seconds will make PTZ control unusable.
- Traffic signal systems have typically operated on a point to multipoint poll/response protocol that requires a response within 50ms or less. Is it realistic to expect wireless or internet based systems to meet the polling latency requirements of a traffic signal system?
Recognize that system reliability and quality are necessary and desirable. But, also recognize that many features and benefits have a cost. Use the "KISS" (keep it simple stupid) principle of system design whenever practical. The requirements document should help answer the following:
- Are there viable alternatives that can help to lower the overall cost?
- Can you obtain better functionality and greater value using an alternative even though it adds cost?
- Will the use of alternatives add to, or reduce, overall system complexity?
- Can the system allow for future growth or technology changes?
There is no magic formula, just the tried and true "five Ws and H" question and answer technique – what, where, when, who, why, and how. The questions are not complex, but the individual answers may point to a series of complex design and implementation issues for the required communications system.
Key points to consider:
- View the communication system as a part of the overall traffic/transportation project. There are many examples of adding the communications network as an afterthought. This eventually causes dissatisfaction with the communications system. The end result is a requirement to spend additional money to correct problems.
- Look at the whole system, not just the immediate construction project. Many ITS programs are developed as part of a roadway construction project. DOTs have been able to build long lengths of highway by breaking the construction into a series of small projects. However, those project sections are in fact part of a larger plan. The communications system should be part of the larger plan. There are too many examples of DOTs adding a different type of communication system to each construction project.
- The communications network must be analyzed and designed to serve the long-term traffic management needs (e.g., what will the ultimate system provide in terms of geographic coverage and functionality). The potential communication needs of other government entities should also be considered in the analysis and design. Don't design a communications system for a highway section project that will be expected to serve as part of a larger network that has not been planned.
- Answer the questions. Take note that most of the answers are provided in the context of traffic and transportation terminology. This is recognition of the purpose of the system – to provide communications capabilities for a traffic/transportation system.
- Each of the six primary questions will lead to secondary questions.
- Follow the process through to a logical conclusion.
Ask the Questions
What is the purpose of the proposed traffic/transportation system? Look at the original project statement of purpose for this answer. Relate the communication requirements to the reason for the project's existence. Most projects require bi-directional information flow. Many require bandwidth to support video from CCTV cameras.
- Will the communications network need to support multiple functions? Each function (traffic volume, traveler information, toll collection, congestion management) will have its own set of communication requirements.
- What is the impact of the "Market Packages" as expressed in the National Architecture to the overall project?
- What National Architecture Standards are envisioned for the system?
- What is the role of communications in the overall traffic/transportation system?
Where will it be located? Location of the project has an impact on overall design of the physical infrastructure and the cost of construction of a communication network. If the project is to be constructed in a narrow mountain pass, it will create challenges that won't be encountered on a local city street. Where is the TMC to be located in relation to the field equipment?
- If the TMC is located on the western edge of a city and the field equipment is located on the eastern edge, how will a communication link be created? Which will be more cost effective – lease, or construct the communications link?
- Location may also impact on the type of communication media. During the "Gee Whiz" discussions, the project team may assume that Free Space Optics (see technology description in chapter 2) would be a good system, but this may be negated by the actual location of the intended system.
When (over what period of time) will it be deployed? This is a question that is directed to the communication network. Does the project plan call for implementation over a relatively short period – one to two years – or a long period – five to eight years?
- During a relatively short deployment time frame, project planners can assume that communication technology will remain stable. The communication system design team can propose a system without concern that communication technology and process will change.
- Taking into consideration the total duration of traffic/transportation projects one could expect that proposed equipment and actually delivered equipment will have changed. Example: a system was specified that required a DS-1 Multiplexer and a separate CSU/DSU. By the time the system was deployed (1.5 years later), most manufacturers were offering a combined DS-1 Mux and CSU/DSU. This lowered overall cost, saved space, and reduced power requirements. The end user – a DOT – required three months of meetings, and substantial paperwork before allowing the change – including the saving of money.
- Given the pace of change and innovation of communication technology and process, managers of long term projects should anticipate changes to equipment specifications. Under these circumstances, it might be wise to allow for a second look at communications technology before the final specifications are published. However, don't make changes that will require a total re-write of the specifications. Look for improvements (or enhancements) that create an overall cost/benefit for the project.
Who will operate and maintain the system? Consider whether the communication system will require that operational personnel activate various functions of the communication equipment. All of the following may have an impact on the overall design of the communication system:
- Will they need to know how to trouble-shoot for communication problems?
- Will they need to be able to effect minor repairs?
- Will they need to configure the operational functions of the communication system?
- Do I have internal staff capable of maintaining the communication system?
- What type of experience and educational qualifications are desirable?
Answering the question of who will operate and maintain the system will lead to operator and maintenance staff qualification requirements. DOTs have personnel regulations and guidelines that have to be met in order to provide staffing. Private contractors supplying operational and maintenance personnel may have to meet other criteria. Outsourcing might be a reasonable consideration.
Why is the traffic system being deployed? This may seem redundant to the question of "what" is being deployed, but at this point the project team will focus on the specific type of traffic system. "Why" might be answered with a look at the research that was used to justify the deployment of the traffic/transportation system. The communication engineers responsible for analyzing and designing the communications system need to be provided with a good understanding of how various types of traffic/transportation systems work. This will lead to a design of the communication system based on the functions of the traffic/transportation equipment. Examples of various systems that should be explained:
- Enforcement controls (Traffic Signal, Speed, etc.)
- Toll Collection
- Traveler Information
- Incident Management
- Traffic Signals
- Ramp Management
- General Traffic Information Collection
- Regional Integration
There are a number of "How" questions to be answered and most are interrelated.
- How many devices will be deployed? A simple question that will have a tremendous impact on the overall design. A large number of devices will increase the bandwidth requirements and may strategically alter the initial communication system concept.
- How many operators at the control center? Another very simple question that may have a significant impact on the design. Related to this is a question that deals with diverse operator (or system control) locations. The number of operators will impact on the communications network within the TCC. Diverse operator locations (different buildings) will have an impact on the entire communication network – in terms of both complexity and cost.
- How much redundancy is required? Redundancy can be viewed from several aspects. Redundant and diverse communication paths will add significantly to the overall cost of the project. It is probable that the total cost will increase by more than double. Redundant communication hardware will impact on the total by the factors of the hardware and installation costs.
- How will regional requirements be met?
- How much will it cost?
- How will it be funded? The reader might wonder – "what's the difference!" Each potential funding source will make payments under specific circumstances. Some may only pay for capital expenditures, while others may pay for capital and operational costs. The communications engineers will want to consider these aspects when making recommendations for the communication system architecture. If 50 percent of the communication system cost is for leased telephone line services, and the primary funding source will only provide for the capital expenditures, the project will lose 50% of its potential funding for communications systems. A public/private resource agreement may only provide for certain types of communication systems and equipment. Joint system development with a portion of the funding being provided by one, or more, additional agencies may add some requirements for the type of system or equipment used. The communication engineer will need to know if the funding arrangements will have an impact on the system design. In later stages of the requirements and design process, the engineer will need a good understanding of the amount of funding allocated for communications systems.
Once the basic questions have been asked and answered the communications engineer will present a preliminary communication systems requirements document. The project design team should review the proposed requirements document, and consider the following:
- Merging Expectations with Reality – At this point, it is time to look at the requirements for the communications system and reconcile original expectations with the realities of what is possible. Compare expectations with the preliminary communication systems design. Ask the communication engineer to fully explain how technical and financial barriers impact on expectations. Challenge the requirements document.
- What Type of Communications System Should I Build? Now that the requirements document has been presented, the project team needs to determine if it should follow all of the suggestions made in the requirements document. There may be new information that was not available when the communications design team started to work on the requirements document.
Three Basic Systems Types:
- Private System – the DOT builds its own system and is totally responsible for the construction, operation and maintenance.
- Public Network Based – the entire system is leased from local telecommunication carriers or other types of communication service providers.
- Hybrid – Public/Private – a combination of the above systems types. In most instances, the DOT will take responsibility for field communication devices and circuits and use leased telecommunication facilities for transport back to the TCC.
Developing a Budget
Once the requirements have been reviewed against expectations, it's time to develop a "real" communication system budget.
- Price out the "ideal" system – have the communications engineers do a comparison between the system described by the requirements document, and the expected system.
- Determine if there are alternatives that will help the project get closer to the expected system without degrading performance criteria suggested in the requirements document.
- Are there viable alternatives that can help to lower the overall cost? The Utah DOT system described in chapter 7 provides a good alternatives example.
- Can you obtain better functionality? What's the marginal cost adjustment for a significant increase in additional functions? Will the additional functions increase the overall cost of maintenance and operation?
- Can the system provide for future growth? Not just amount of capacity, but the ability to handle (accept) technology changes.
A few simple guidelines to follow:
- There's no magic formula
- Make certain that the communications engineering team is part of the overall project team.
- Don't let the communications engineering team act as an independent agent without direction.
- Assure that they receive significant input from the overall project team.
- Don't let the "techno-speak" (language of the communications engineers) be a creative engineering barrier.
- Investigate, and make certain that you have selected the right communication engineering team partner.
- Don't be afraid to ask questions and seek explanations. It's your system, you have a right to know!