Chapter 11. Appendix
IEEE 802 Standards & Working Groups
Comparison Analog Voice & VoIP
- Technology – analog to digital. VoIP erases the line between voice and data. VoIP converts analog information (the human voice) into data packets, the same digital containers used to shuttle email messages and download web pages.
- Network – PSTN to IP. A traditional phone call stakes out a single path over the public switched telephone network (PSTN). VoIP uses Internet Protocol, the language of the Internet. It separates a conversation into packets, which flow over data networks – the Internet, company intranets, or proprietary IP networks managed by Carriers (such as: Verizon, SBC, Sprint, MCI, etc) or alternate service providers (such as: AOL, COMCAST, etc.).
- Network connection – phone line to broadband. In a traditional voice system, desktop phones connect to the outside world via a telephone line, and data systems connect through a data/broadband network. With VoIP, phones plug into a broadband connection (through a modem or similar device) or the in-house company LAN. This convergence helps to drive down costs by combining the voice and data networks.
- Phone numbers – place to device. In the pre-VoIP world, a phone number belongs to a location. With VoIP, the number goes with the device.
Calculating Fiber Optic Loss Budget
Criteria & Calculation Factors
Design of a fiber optic system is a balancing act. As with any system, you need to set criteria for performance and then determine how to meet those criteria. It's important to remember that we are talking about a system that is the sum of its parts.
Calculation of a system's capability to perform is based upon a long list of elements. Following is a list of basic items used to determine general transmission system performance:
- Fiber Loss Factor – Fiber loss generally has the greatest impact on overall system performance. The fiber strand manufacturer provides a loss factor in terms of dB per kilometer. A total fiber loss calculation is made based on the distance x the loss factor. Distance in this case the total length of the fiber cable, not just the map distance.
- Type of fiber – Most single mode fibers have a loss factor of between 0.25 (@ 1550nm) and 0.35 (@ 1310nm) dB/km. Multimode fibers have a loss factor of about 2.5 (@ 850nm) and 0.8 (@ 1300nm) dB/km. The type of fiber used is very important. Multimode fibers are used with L.E.D. transmitters which generally don't have enough power to travel more than 1km. Single mode fibers are used with LASER transmitters that come in various power outputs for "long reach" or "short reach" criteria.
- Transmitter – There are two basic type of transmitters used in a fiber optic systems. LASER which come in three varieties: high, medium, and low (long reach, medium reach and short reach). Overall system design will determine which type is used. L.E.D. transmitters are used with multimode fibers, however, there is a "high power" L.E.D. which can be used with Single mode fiber. Transmitters are rated in terms of light output at the connector, such as -5dB. A transmitter is typically referred to as an "emitter".
- Receiver Sensitivity – The ability of a fiber optic receiver to see a light source. A receiving device needs a certain minimum amount of received light to function within specification. Receivers are rated in terms of required minimum level of received light such as -28dB. A receiver is also referred to as a "detector".
- Number and type of splices – There are two types of splices. Mechanical, which use a set of connectors on the ends of the fibers, and fusion, which is a physical direct mating of the fiber ends. Mechanical splice loss is generally calculated in a range of 0.7 to 1.5 dB per connector. Fusion splices are calculated at between 0.1 and 0.5 dB per splice. Because of their limited loss factor, fusion splices are preferred.
- Margin – This is an important factor. A system can't be designed based on simply reaching a receiver with the minimum amount of required light. The light power budget margin accounts for aging of the fiber, aging of the transmitter and receiver components, addition of devices along the cable path, incidental twisting and bending of the fiber cable, additional splices to repair cable breaks, etc. Most system designers will add a loss budget margin of 3 to 10 dB
Calculating a "Loss Budget"
Let's take a look at typical scenario where a fiber optic transmission system would be used.
Two operation centers are located about 8 miles apart based on map distance. Assume that the primary communication devices at each center is a wide area network capable router with fiber optic communication link modules, and that the centers are connected by a fiber optic cable. The actual measured distance based on walking the route , is a total measured length (including slack coils) of 9 miles. There are no additional devices installed along the cable path. Future planning provides for the inclusion of a freeway management system communication link within 5 years.
Note: All distance measurements must be converted to kilometers. Fiber cable is normally shipped with a maximum reel length of 15,000 feet (or 4.5km). 9 miles is about 46,000 feet or 14.5km. Assume that this system will have at least 4 mid-span fusion splices.
| Fiber Loss | 14.5 km × 35dB = -5.075 |
|---|---|
| Fusion splice Loss | 4 × .2dB = -.8 |
| Terminating Connectors | 2 × 1.0dB = -2.0 |
| Margin | -5.0 |
| Total Fiber Loss | -12.875 |
The manufacturer of the router offers three transmitter/receiver options for single mode fiber:
| Reach | Transmit Power | Receiver Sensitivity |
|---|---|---|
| Short | -3dBm | -18dBm |
| Intermediate | 0dBm | -18dBm |
| Long | +3dBm | -28dBm |
To determine the correct power option add the transmit power to the fiber loss calculation.
| Reach | Transmit Power | Fiber Loss | Loss Budget |
|---|---|---|---|
| Short | -3 | -12.875 | -15.875 |
| Intermediate | 0 | -12.875 | -12.875 |
| Long | +3 | -12.875 | -9.875 |
Compare this to the receiver sensitivity specification
| Reach | Receiver Sensitivitiy | Loss Budget | Difference |
|---|---|---|---|
| Short | -18 | -15.875 | +3.0 |
| Intermediate | -18 | -12.875 | +6.0 |
| Long | -28 | -9.875 | +19.0 |
Because a loss margin of 5.0dB was included in the fiber loss calculation, the short reach option will provide sufficient capability for this system. In fact, the total margin is 8.0db because the difference between the loss budget and receiver sensitivity is 3.0db.
Rural Telecommunications Requirements Testimony
Steve Albert – Senate Hearing
United States Senate
Committee on Environment and Public Works
Subcommittee on Transportation, Infrastructure and Nuclear Safety
Hearing on Intelligent Transportation Systems Program
September 10, 2001, 3:30 p.m.
Oral Testimony of Stephen Albert, Director
Western Transportation Institute, Montana State University and President, Rocky Mountain Chapter of Intelligent Transportation Society of America
Good afternoon Chairman Reid, Ranking Member Inhofe, and members of the Committee. I would like to begin by thanking you for this opportunity to share our views and perspective on Intelligent Transportation Systems and specifically Advanced Rural Transportation Systems or rural ITS.
My name is Stephen Albert, I am the director of the Western Transportation Institute at Montana State University. WTI's mission is to "make rural travel and transportation safer, more convenient and more accessible." Founded in 1994 by the California Department of Transportation, Montana Department of Transportation and MSU, WTI is the nation's leading research Center focusing on rural transportation issues. With over 30 ongoing research, demonstration and evaluation projects in 30 states and 10 National Parks, WTI was recognized in 1998 by ITS America for our "outstanding achievement in rural ITS." In addition to serving as WTI's director I also serve as the Rocky Mountain ITS America Chapter president.
I am here representing not only western states, but the entire rural community and we thank each of you for raising awareness of rural America transportation needs and ITS applications. My testimony was developed from speaking with stakeholder groups on the east coast, southern United States, mid-west and Alaska.
My testimony will address the following three areas:
- magnitude and severity of rural transportation challenges facing this nation;
- specific examples and benefits of successful ITS deployment;
- future focus areas where additional emphasis and resources should be placed.
1. What are the Rural Challenges?
For the last ten years the rural constituents have heard our transportation leaders highlight congestion as our nation's leading challenge. Programs such as Operation Time Saver, Model Deployment Initiative and other urban initiatives have been the showcase of USDOT. However, these showcase programs have little, if any, direct application to approximately eighty-percent (80%) of our nation's surface roads, or roughly four million miles of roadway. Unlike urban areas that have congestion as the primary single issue, rural needs are more diverse, complex and only tangentially congestion-related. So what are the rural challenges?
1.1 Safety and Non-Interstate Roadways
In rural areas safety is of paramount importance. According to Federal Highway Administration (FHWA) statistics, sixty-percent (60%) of the crash fatalities occur on rural highways, while only 39% of the vehicle miles traveled occur on these roads – a disproportionate relationship. These combined facts make rural crash rates 2.5 times greater than urban areas. Furthermore, single vehicle crashes on 2-lane rural roads accounted for 54% of all rural crashes in 1998.
1.2 Digital Divide – no wireless communication coverage
Vast rural areas of the United States are without wireless communications, which impacts safety and increases infrastructure deployment costs. Preliminary research conducted by WTI in five western states indicates that the notification time to learn of a crash is two to three times longer where no wireless communication exists, and near jurisdictional borders.
1.3 Weather Impacts Every Day Life
Weather can be deadly in many regions of the United States. According to FHWA, there are approximately 7,000 fatalities and 450,000 persons injured each year due to weather related events.
1.4 Tourism and Economic Viability
Tourism is a critical concern to the economic viability of many rural communities. Travel and tourism in the United States is the nation's largest export industry and second largest employer, accounting for over $515 billion in expenditures, resulting in 7.6 million jobs and accounting for 1.3 billion domestic trips. An efficient transportation system is essential to rural communities who depend on tourism revenues for their survival. Providing real-time information to tourists, via ITS, is the key to encouraging greater tourist activity in rural areas and enhancing their economies.
1.5 Federal Lands, National Parks and Native Americans
In order to provide a framework on the impact of the National Parks, consider the following statistics:
- Scale – 374 parks in 49 states, 18 million acres;
- Employees – 19,200;
- Economic activity - $14 billion, supporting 309,000 jobs; and
- Visitation – 266 million visitors, demand increasing 500 percent over the next 40 years.
The second area is our sovereign Native American lands where safety, economic viability and transportation are the key issues. Research has shown that Native Americans die in motor vehicle crashes at rates six times that of the rest of the Nation and 3/4 of Native American traffic fatalities involve alcohol. Also, only 29% of tribes have any form of transit system.
1.6 Animal Conflicts
Each year there are approximately 726,000 animal-vehicle crashes. These crashes rarely result in fatalities but at approximately $2000 per incident in property damage the annual cost nationally amounts to over $1 billion.
1.7 Public Mobility
According to the Federal Transit Administration, approximately 38 percent of the rural population has no access to public transportation and another 28 percent has little access. Low population density in rural service areas makes it difficult at best to deliver public transit services.
1.8 Commercial Vehicles, Goods Movement and Long-distance Trips
The movement of goods is critical to the economy of the United States and the rural Interstate System is an essential component in the process. Rural interstates are, in essence, the arteries over which flow the goods to be distributed to citizens throughout the country. On many rural highways, 30 percent of traffic is commercial vehicles, and their numbers continue to grow.
1.9 Diversity and Understanding
Rural areas are challenged in that there are few issues and application similarities among different locations and regions (i.e. Cape Cod, Mass, Brandon, VT and Eureka, CA).
I believe very strongly that now is the time for USDOT to step up to the plate and provide a level playing field and provide adequate resources to respond to rural transportation needs by providing sufficient funding and guidance that urban areas have enjoyed over the last several years.
2. Advanced Rural Transportation Systems Success Stories
Now, having made that last statement, I do want to recognize a number of success stories that have taken place in rural areas.
2.1 Crash Prevention and Security
Colorado DOT has implemented a dynamic downhill speed warning system on I-70 west of Denver, outside the Eisenhower Tunnel. The system measures truck speeds, weight, and number of axles and advises the driver of the appropriate speed. The truck speed warning system was installed on a narrow curve that has a design speed of 45 mph. The average truck speed around this curve has dropped from 66 mph to 48 mph since the installation of the warning system. The system has eliminated approximately 20 truck runaways and 15 truck related crashes per year. California DOT has implemented a similar speed system for passenger cars and trucks near Redding California along I-5 in Sacramento Canyon.
2.2 Emergency Services
Virginia DOT sponsored the Northern Shenandoah Valley Public Safety Initiative to enhance the collection and communication of critical accident victim patient data between the on-scene emergency medical personnel and the receiving hospital through the use of hand-held portable digital assistance devices. Use of the off-the-shelf PDA's has improved patient outcome, improved on-scene, en-route and emergency room patient services, improved data collection, all in addition to incident management coordination.
2.3 Tourism and Traveler Information
As you know our National Parks are experiencing increasing visitation and traffic congestion. The Yellowstone National Park Smart Pass will provide frequent users and local residents with an electronic pass and a designated lane at entrance gates to bypass congestion. Similar systems are being implemented in Rocky Mountain and Zion National Parks.
2.4 Traffic Management
The Arizona DOT and Oregon DOT utilize the internet whereby organizations can enter road closure, lane restrictions, unsafe road conditions, and parking information into the system and all agencies can view the status of those conditions. The ODOT TripCheck system includes images from closed circuit cameras at mountain passes and other locations. During the peak usage the number of users have exceeded 350,000 per month.
2.5 Surface Transportation and Weather
Accurate road and weather information can mean the difference between life and death.
The Greater Yellowstone Weather and Traveler Information System will integrate a mountain pass pavement temperature prediction model, and a road and weather condition information system that delivers trip-specific weather forecast and road reports via cellular telephone by dialing #SAFE. The #SAFE system will provide road and weather information 40 to 60 miles (or 1 to 1½ hours travel time) ahead of the direction of travel. The #SAFE system has been used by over 300,000 motorists, with a monthly average of 16,000 per month and the median use of the system is 25 times per year mostly in the winter.
2.6 Operations and Maintenance
In California and Arizona, the state DOTs have instrumented snowplows and the mountain pass roadways with technologies to allow for vehicle tracking in the roadway for lane guidance and collision avoidance systems to warn motorists of close proximity.
3. What are the Future Needs?
While there have been success stories as highlighted by my previous testimony, there are some very real gaps and opportunities that must be addressed. As I mentioned earlier, USDOT has predominately concentrated on urban ITS and discounted the need to address rural challenges in any realistic programmatic level. To quote one DOT Chief Engineer, "the highest use is not necessarily the highest need." The time to address rural needs has arrived and we need federal leadership and commitment. The following recommendations are proposed from rural ITS constituents around the country.
3.1 Conduct Outreach and Professional Capability Building Seminars
Given that federal dollars to develop Early Deployment Plans were only available to urban areas with populations over 50,000 and guidelines exist that regionally significant projects need to develop regional architecture, there should be a commitment to provide outreach and training in rural areas more than at just a statewide level. Also, it is important that these outreach and professional capability building activities occur in rural communities where stakeholders live rather than large urban centers.
3.2 Integrate Funding and Increase Awareness
To integrate funding and increase awareness of opportunities, it is recommended that a blue-ribbon committee be formed to create a one-stop shopping process or even a clearinghouse, develop an awareness program for rural funding opportunities, review the project initiation approval process, and determine if a block-grant approach may be more feasible for ITS deployment that would horizontally cut-across federal agencies.
3.3 Improve Communications Coverage to Provide a Basic Level of Detection, Increased Safety and Reduced Deployment Cost
If we are to manage our rural roadways in a safe and prudent manner then some level of basic infrastructure to detect problems and a communication system to transmit that data must be created and funded. Rural America has large pockets of "dead zones" (no cellular wireless service). A new or improved model needs to be developed to increase communications coverage. This new model may be similar to the Rural Utility Service but at a minimum it may require a federal subsidization for private carriers that cannot achieve the return on investment that the high volume urban subscriber models deliver.
3.4 Develop Regional Projects and Partnerships
Travelers do not see the jurisdictional state boundaries, nor do they care, and yet most ITS projects are developed with only a single state in mind. Regional scale projects focused on the travel sheds that motorists use need to address a national system and to encourage public-private partnerships to develop the economies of scale needed to minimize risk.
3.5 Implement Regional Servers for Data and Information Exchange between Stakeholder Groups
To accelerate the ability to exchange data and information to provide for communication, cooperation and coordination, funds should be allocated to implement regional "internet" based servers throughout the 50 states.
3.6 Increase Research Funding and Provide for More Adaptive Standards
To date there has been only a marginal amount of research as to the quantified benefits of rural ITS. Funding for research, specifically targeted for rural ITS, should be set aside to allow for a more robust evaluation of current and planned deployment.
3.7 Create a Rural Model Deployment Initiative
If the USDOT truly wants to take a leadership role, then an opportunity I recommend is to create a Rural Model Deployment Initiative similar to the Metropolitan Model Deployment Initiative, but concentrated on a more regional/rural scale.
3.8 Build on Successful Tourism Partnerships to Create Jobs
Tourism is the economic engine of rural America! To allow ITS to be more effective the focus and attention toward tourism partners that may ultimately be the implementers of ITS must be increased to spur economic activity and create jobs.
In closing, while there are isolated success stories that can be highlighted, there are still many challenges yet to be addressed. In keeping to the rural spirit, the Subcommittee and USDOT have an opportunity to be "pioneers" in making a renewed rural ITS commitment. As we like to say in the West – Our forefathers were pioneers, not settlers!
