By the end of Lesson 4, you should be able to:
Lesson 4 will take 1 week to complete. Please refer to Canvas for specific timeframes, submission instructions, and due dates.
To finish this lesson, you must complete the assignments listed below. The details for each assignment are provided in the referenced section and in Canvas.
Assignment No. | Assignment Description | Section | Grade Component / Points |
---|---|---|---|
4-1 | Watch a webinar on creating a network dataset in ArcGIS and answer some questions. | 4.1 | Lesson Topic / 20 |
4-2 | Complete a tutorial to create a network dataset from street data. | 4.1 | Lesson Topic / 15 |
4-3 | Learn about the FHWA and answer some questions about the NHS and GDC initiative. | 4.2 | Transportation Organizations / 15 |
4-4 | Participate in a One-on-One video conference with a classmate and submit a summary of the c.onversation. | 4.3 | Class Participation / 15 |
4-5 | Participate in this week’s webinar and submit a summary of what you learned. | 4.5 | Guest Webinar / 15 |
4-6 | Review the background material for next week’s webinar and respond to some questions. | 4.6 | Guest Webinar / 10 |
4-7 | Submit 3 – 5 questions for next week’s speaker. | 4.6 | Guest Webinar / 5 |
People and goods can move from one location to another by traversing a transportation network. There are many types of transportation networks including street networks, railroad networks, pedestrian walkway networks, river networks, utilities networks and pipeline networks. A geospatial model of a transportation network is comprised of linear features and the points of intersection between them. The modeling and analysis of networks has so many applications that there is an entire branch of mathematics devoted to it known as graph theory. In graph theory, linear segments of the network (e.g. road segments) are referred to as edges and the points where the linear segments connect are called nodes.
Some transportation networks permit travel in both directions such as street networks and are referred to as undirected networks. Other networks generally limit travel to a single direction such as pipeline networks. These networks are referred to as directed networks. In ArcGIS, undirected networks are modeled with network datasets whereas directed networks are modeled as geometric networks. In this course, we will limit our study to street networks and the use of network datasets to model them.
Many transportation problems can be addressed through a network. A few examples are listed below:
We will take a detailed look at some of the more common network analyses in the next lesson. In this lesson, we will focus on the components of a transportation network model and the mechanics of creating one.
While a high-quality set of roadway centerline data is certainly a prerequisite to modeling a transportation network, it is by no means sufficient. Other important elements of a network model include the following:
The topology of a street network refers to the spatial arrangement and connectivity of the roads which comprise the network. Understanding how the road features relate and connect is critical in determining which paths or routes through the network are possible. Elevation is an important consideration in establishing network topology. Physical connections between streets require not only that they cross in the x-y plane but also that they cross at the same elevation. The picture below shows a complex interchange where many roads cross but there are limited points of connectivity.
In order to select the “best” route between two points in a network, you need to define what you are trying to accomplish. Perhaps you’re interested in determining the shortest route. In this case, you would need to know the distance between all adjacent nodes in the network. Consequently, the edges would need to have an attribute which quantifies length. Alternatively, if you want to know the fastest route between two points you need to know the time it takes to move between any two adjacent nodes. Consequently, to support a fastest route determination, the edges need to have an associated time attribute or a speed limit attribute, since time is a function of length and speed limit. Regardless of how you define “best”, you need to have a corresponding attribute or attributes which allow the cost of potential routes to be quantified and compared. For example, if you want to know the most scenic route between any two points in the network you would need to have a scenic score attribute associated with each edge which quantifies its scenic value.
Turns also play a key role in modeling a street network. One fundamental consideration in regards to turns is whether they are permitted. Many road intersections do not permit U-turns for example. A second consideration for turns is the length of time they take. Left turns generally take longer to complete than right turns since you generally have to contend with oncoming traffic. In order to accurately estimate how long it would take to traverse a network along a specific route, turn delays need to be taken into account.
Another important data element for a street network relates to one-way roads. In order to ensure that only legitimate routes are considered, roads which limit travel to one direction need to be identified.
We all know that traffic plays an important role in determining how long it takes to traverse a particular route. Consequently, historic traffic data, or better yet live traffic data, can be extremely useful in a street network model.
Often one of the desired outputs of network analysis is a set of description directions. In order to support the production of meaningful directions, a variety of descriptive roadway attributes needs to be present. Signpost data can also provide a valuable source of information for the creation of meaningful directions.
As you can see, a lot of information is required beyond basic roadway centerline geometry in order to create a street network which can support network analysis and produce high-quality results.
Watch this video from ESRI’s 2013 User Conference [1] which talks about constructing a network dataset. Address the following questions and submit your responses in the form of an M.S. Word document to Assignment 4-1 in Canvas.
Download the ESRI ArcGIS Network Analyst Tutorial Data [2] and complete Exercise 1: Creating a Network Dataset [3]. After completing the exercise, address the following items and submit your responses in the form of an M.S. Word document to Assignment 4-2 in Canvas.
This week, you’ll take some time to get to know the Federal Highways Administration (FHWA), an important agency within the USDOT. The roots of the FHWA trace back to its first predecessor organization known as the Office of Road Inquiry (ORI) which was created by President Grover Cleveland in 1893. In the days before the automobile, Interstate travel was dominated by railroad and it was actually a bicycle boom which was largely behind the initial interest in improving America’s roads. An interesting history of the FHWA can be found here [4]. A signature achievement in the advancement of America’s roads was the development of the Interstate system of roadways championed by President Dwight D. Eisenhower. Today, the Interstate system represents about 50,000 miles of highway and is responsible for about one-quarter of the vehicle miles traveled on America’s roadways.
The primary function of the FHWA is to assist states and local governments with the design, construction, and maintenance of roads and bridges and to ensure US roads and highways meet a high standard of safety and quality. The primary mechanism through which the FHWA supports states and local governments is the Federal Aid Program. This program looks to focus federal monies on the nation’s most important roadways.
The Intermodal Surface Transportation Efficiency Act of 1991 introduced the concept of the National Highway System, a system of roads and highways deemed critical to America’s economy, defense, and/or mobility. Through the efforts of FHWA working with other federal, state, and local partners roughly 160,000 miles of roadway were identified for inclusion in the NHS. The National Highway System Designation Act of 1995 signed into law by President Bill Clinton officially designated these roadways as the NHS.
A brief but informative article on the NHS titled The National Highway System: A Commitment to America's Future [5] appeared in a 1996 edition of Public Roads, a bimonthly magazine published by FHWA.
One of the FHWA’s key objectives is to encourage innovation and to provide states and local governments with needed technical assistance. A recent FHWA initiative known as Geospatial Data Collaboration [6] (GDC) is aimed at promoting the use of GIS tools to facilitate data sharing and increased collaboration between transportation agencies and resource agencies with the ultimate objective of more timely project delivery.
Submit an M.S. Word document to Assignment 4-3 in Canvas which addresses the following items:
This week you’ll have a one-on-one chat with one of your classmates as per the schedule you were provided in Week 1. The discussion should be at least 30 minutes in length. If it’s the first time you’ve chatted with each other, spend the majority of time getting to know each other. Otherwise, focus on discussing the lesson content.
Submit a brief summary of the conversation (no more than 300 words) to Assignment 4-4 in Canvas. The summary you’ll submit is an individual assignment and is not intended to be a joint activity. If it’s the first time you’ve spoken with each other, your summary should primarily address what you learned about each other (e.g., what do you have in common?). Otherwise, your summary should focus on ideas and insights about the lesson content which came out of the conversation.
Criteria | Ratings | Pts | ||
---|---|---|---|---|
Followed Instructions | Excellent: Student carefully followed all instructions for the assignment. 4.0 pts |
Satisfactory: Student's submission exhibited some minor deviations from the instructions for the assignment. 2.5 pts |
Poor: Student's submission exhibited major deviations from the instructions for the assignment. 1.0 pts |
4.0 pts |
Content Quality | Excellent: Student's submittal reflected a conversation which was highly thoughtful and productive and provided substantial benefit in getting to know each other better and / or exploring lesson topics. 7.0 pts |
Satisfactory: Student's submittal reflected a conversation which was somewhat thoughtful and productive and provided some limited benefit in getting to know each other better and / or exploring lesson topics. 5.0 pts |
Poor: Student's submittal reflected a conversation which had little value in getting to know each other better and / or exploring lesson topics. 1.0 pts |
7.0 pts |
Writing Quality | Excellent: Student’s writing was organized, clear, and concise and was free from spelling and grammatical errors. 4.0 pts |
Satisfactory: Student’s writing exhibited some deficiencies in the area of organization, clarity, and conciseness and/or contained a few spelling or grammatical errors. 2.5 pts |
Poor: Student’s writing exhibited major deficiencies in the area of organization, clarity, and conciseness and/or contained many spelling or grammatical errors. 1.0 pts |
4.0 pts |
Total Points: 15.0 |
This week’s speaker is Mr. Greg Ulp. For details about Greg’s current role and background refer to Lesson 3. For the specific date and time of the webinar, please refer to Canvas. While you are expected to attend the webinar live, if at all possible, it is understood that, in some cases, work schedules and other conflicts may make it impossible to do so. If you will not be able to attend, please send me an e-mail ahead of time. I will make the recorded webinar available for you to review.
After attending the webinar, prepare a brief write-up (250 – 500 words) summarizing the session and submit it in M.S. Word format to Assignment 4-5 in Canvas. In your summary, address the following:
Criteria | Ratings | Pts | ||
---|---|---|---|---|
Followed Instructions | Excellent: Student carefully followed all instructions for the assignment. 4.0 pts |
Satisfactory: Student's submission exhibited some minor deviations from the instructions for the assignment. 2.5 pts |
Poor: Student's submission exhibited major deviations from the instructions for the assignment. 1.0 pts |
4.0 pts |
Content Quality | Excellent: The student's submittal demonstrated that the student paid close attention during the webinar and carefully reflected on the key topics which were covered. 7.0 pts |
Satisfactory: The student's submittal demonstrated that the student was somewhat attentive during the webinar and engaged in limited reflection on the key topics which were covered. 4.0 pts |
Poor: The student's submittal provided little or no evidence that the student paid careful attention during the webinar or reflected on the topics which were covered. 1.0 pts |
7.0 pts |
Writing Quality | Excellent: Student’s writing was organized, clear, and concise and was free from spelling and grammatical errors. 4.0 pts |
Satisfactory: Student’s writing exhibited some deficiencies in the area of organization, clarity, and conciseness and/or contained a few spelling or grammatical errors. 2.5 pts |
Poor: Student’s writing exhibited major deficiencies in the area of organization, clarity, and conciseness and/or contained many spelling or grammatical errors. 1.0 pts |
4.0 pts |
Total Points: 15.0 |
Next week, our guest speaker will be Mr. Frank DeSendi. Frank is the Manager of PennDOT’s Geographic Information Division and is also a former Chair of the American Association of State Highway Transportation Officials’ GIS for Transportation (AASHTO GIS-T) Task Force. He began his career with PennDOT in 1989 and has been working in the geospatial field since 1995. Frank holds a Bachelor of Science in Geography from The Pennsylvania State University.
One interesting use of spatial technology which Frank’s group implemented a few years ago is called LPN which stands for Linking Planning and NEPA. PennDOT and its planning partners (i.e., the MPOs and RPOs) use the application to screen potential projects against more than forty environmental datasets which collectively address most NEPA concerns. Based on the proximity of a proposed transportation project to these resources, the application determines a score which can be used to compare various alternatives for the project. The user’s guide for the application is here [7].
In the past, transportation planning and the development of TIPs and STIPs occurred with little thought given to environmental and cultural resources and community concerns. Later in the project development process, when the design and construction of the project were eminent, the potential impacts to these resources were considered as is required by NEPA. If, through this NEPA review process, the project was anticipated to have potential impacts on these resources, it often led to substantial delays in project delivery, unexpected increases in the project budget and a less than ideal solution for all involved. Consequently, significant efforts have been made in the past 15 years to begin assessing potential impacts to resources early in the planning process and for transportation agencies to work more closely with resources agencies. Spatial technologies have played a large role in facilitating potential impact assessments, identifying alternatives that eliminate or minimize impacts and, when impacts are unavoidable, identifying mitigation strategies which can offset any negative impacts of the project.
In response to the need to more closely integrate transportation planning and environmental review, FHWA created the Planning and Environmental Linkages (PEL) program to help state DOTs, MPOs and RPOs revise their planning processes, improve their coordination with resource agencies and develop tools to streamline the entire process.
Watch the 2011 webinar (72 minutes) jointly sponsored by FHWA and AASHTO titled Linking Transportation and Natural Resource Planning through the use of Environmental GIS Tools [8] and submit an M.S. Word document to Assignment 4-6 in Canvas which addresses the following questions:
After reviewing the background material for next week’s webinar and the biography for next week’s speaker, come up with 3-5 questions which are clearly stated and are relevant to the webinar topics. Submit the questions to Assignment 4-7 in Canvas.
Criteria | Ratings | Points | ||
---|---|---|---|---|
Question Quality |
Excellent: Questions were clearly worded, demonstrated a thorough review of the background material and thoughtful reflection and insight on the part of the student.
5.0 pts
|
Satisfactory: Questions were somewhat clear, demonstrated some review of the background material and some reflection and insight on the part of the student.
3.0 pts
|
Poor: Questions were unclear and/or demonstrated little or no review of the background material and/or demonstrated little or no reflection and insight on the part of the student.
1.0 pts
|
5.0 pts |
Total Points: 5.0 |
In this lesson, we learned about transportation networks. Specifically, we examined the elements which comprise a network and the activities that go into creating one. You then had the opportunity to solidify this knowledge by modeling a transportation network in ArcGIS through the construction of a network dataset from roadway centerlines and other associated data.
Our transportation organization of the week was the FHWA. You learned a little about the history and key roles of the FHWA. We also took a look at NHS, a network of roadways deemed critical to the nation and FHWA’s geospatial data initiative known as the GDC.
In our weekly webinar, we had the opportunity to interact with Mr. Greg Ulp, a senior project manager who was the technical architect for MPMS-IQ, a GIS application used by PennDOT to disseminate project information to the public and other interested parties.
In preparation for next week’s webinar, we learned how transportation planning and the NEPA review processes which seek to assess and mitigate environmental impacts related to transportation projects have become more tightly integrated and about the role GIS has played in helping to bring the two together.
Finally, you had the opportunity to get to know one of your classmates a little better and share some of your ideas and questions about this week’s lesson materials.
If there is anything in the Lesson 4 materials about which you would like to ask a question or provide a comment, submit a posting to the Lesson 4 Questions and Comments discussion in Canvas. Also, review others’ postings to this discussion and respond if you have something to offer or if you are able to help.
Links
[1] http://www.esri.com/videos/watch?videoid=2556&isLegacy=true&title=network-analystcreating-network-datasets
[2] http://www.arcgis.com/home/item.html?id=d6bd91b2fddc483b8ccbc66942db84cb
[3] http://desktop.arcgis.com/en/arcmap/10.4/extensions/network-analyst/exercise-1-creating-a-network-dataset.htm
[4] http://www.fhwa.dot.gov/infrastructure/history.cfm
[5] http://www.fhwa.dot.gov/publications/publicroads/96spring/p96sp2.cfm
[6] http://www.fhwa.dot.gov/everydaycounts/edctwo/2012/gis.cfm
[7] http://www.dot.state.pa.us/Intranet/PennDOT/lpnforms.nsf/0/83AFD7C3DF50E2C3852578CB0079D6F9/$FILE/LPN_User_Guide.pdf
[8] http://connectdot.connectsolutions.com/n134083201106