GIS for Transportation: Principles, Data and Applications

7.5 Next Week's Webinar


Next week we'll hear from 2 speakers.

Speaker #1

Our first speaker will be Mr. Jeff Roecker. Jeff graduated from Penn State with a degree in Geography and joined PennDOT in 2008. Jeff plays a lead role in the Department's Crash Data Analysis and Retrieval Tool (CDART), and he is the project manager for PennDOT's Strategic Highway Safety Plan (SHSP).

Crash Data Collection

FHWA requires all states to maintain a database of crashes in order to support the analysis of crash locations. There is variation from state to state on how they define reportable crashes, how they collect the information and how readily they share the information. Many states publish annual summaries of crash data for the prior year and also provide trending information for various crash statistics. The Pennsylvania Department of Transportation (PennDOT) publishes an annual report entitled Crash Facts and Statistics. The 2016 version of this publication can be found here.

Crash data is important to state DOTs for a number of reasons. First, without this data, an agency doesn’t know if things are improving. Second, this data can offer clues to where safety improvement or countermeasures are most needed. Crash patterns can also be used to help law enforcement design initiatives associated with seat belt usage and checkpoints for impaired drivers.

Law enforcement officials are generally responsible for reporting crashes. In Pennsylvania, the Commonwealth of Pennsylvania Police Officers Crash Report Manual provides law enforcement agencies instructions on reporting crash data including definitions of which types of crashes are reportable to PennDOT. The police use a multipage form (AA 500) to report crash data. The form captures extensive information about the crash including the location, all vehicles and individuals involved in the crash, the number and nature of any injuries, weather and road conditions at the time of the crash, a diagram of the crash and statements from any witnesses. PennDOT also provides a detailed reference document known as Pub 153 to help police officers complete the form correctly.

PennDOT also has a web-based system called the Crash Reporting System (CRS) which provides an electronic alternative to submitting crash data. A user’s guide for the system can be found here. CRS is also used by PennDOT to review and validate all data which is automatically retrieved from paper forms which are received from law enforcement agencies. Any meaningful analysis of crash data requires that the data is accurate and complete.

Crash Analysis

State DOTs use crash data to identify locations where there are unusually high crash rates and also to determine measures which will likely lower these crash rates. One of the most useful types of crash analysis, which is used by many state DOTs, is a spatial technique known as cluster or hot spot determination. This type of determination is done using GIS software by stepping along each route and identifying sections of roadway which meet the definition of a crash cluster based on established parameter settings for the analysis.

In Pennsylvania, crash data submitted by law enforcement agencies electronically via CRS or the AA500 paper form, are processed and stored in a system known as the Crash Data Access and Retrieval Tool (CDART). CDART is a geospatial application which allows PennDOT to perform a variety of crash analyses including crash cluster analyses. It performs two basic types of crash cluster analysis. The first is a standard cluster analysis where each road is considered separately. The second is an intersection-based cluster which examines the number of crashes which occur on all associated roads within a certain distance of the point of intersection. One of the other interesting analyses CDART performs is a “before and after” analysis which compares crash frequencies for a section of roadway before and after a safety improvement was implemented to determine its effectiveness. For each of the analyses CDART performs, the system allows the user to generate tabular or map-based outputs. CDART is an internal tool to PennDOT and is not available for public use.

On May 30, 2013, Sharon Hawkins of the Arkansas DOT gave a 42-minute presentation on some of the GIS tools they use to locate and analyze crashes. The presentation was part of the FHWA GIS in Transportation webinar series. The webinar provides an excellent perspective on the importance of GIS in collecting and analyzing crash data. Many states have gone through a similar evolution and set of problems in their efforts to manage and utilize crash data to improve highway safety.

Assignment 7-6 (10 points)

Review the Pennsylvania Police Crash Reporting form and associated guidance for reporting crashes and watch the Arkansas DOT’s May 2013 webinar on GIS tools they’ve used to locate crashes and analyze crash data. Address the questions listed below and submit your responses as an M.S. Word document to Assignment 7-6 in Canvas.

  1. How does Pennsylvania define a reportable crash? (1 point)
  2. What are some types of information a police officer can provide to locate a crash in Pennsylvania? (1 point)
  3. Why is it important for PennDOT (or any state DOT) to ultimately associate a crash with a specific location along a roadway as opposed to simply capturing the coordinates of the crash? (1 point)
  4. In Arkansas’s evolution of locating crashes, they deployed GPS units to the police to help them accurately locate a crash. What was one of the problems they identified after providing these units to the police? (1 point)
  5. What are some of the GIS tools Arkansas DOT has rolled out to help law enforcement locate crashes? (2 points)
  6. How does Arkansas DOT benefit from law enforcement’s ability to more accurately locate crashes? (2 points)
  7. Come up with 2 – 4 questions for Jeff. (2 points)

Speaker #2

Our second speaker will be Mr. Jeremy Freeland. Jeremy is a Transportation Planning Manager in the Transportation Planning Division of PennDOT’s Bureau of Planning and Research. He is responsible for coordinating and overseeing all of PennDOT’s traffic collection efforts, both manual and automated. He is also responsible for assembling PennDOT’s annual Highway Performance Monitoring System (HPMS) submittal to the Federal Highway Administration (FHWA). Jeremy has been with PennDOT for 13 years. He earned a geography degree from Shippensburg University in 2003.

Highway Performance Monitoring System (HPMS)

FHWA is responsible for collecting sufficient highway characteristics and performance data in order to support their own needs as well as those of the USDOT and Congress. HPMS is a national information system which was created to fulfill this need. Initially developed in 1978 as a replacement of biennial roadway condition studies which began in 1965, one of the primary purposes of HPMS is still to provide Congress with a biennial assessment of U.S. roads for use in estimating future highway investment needs. Here is a link to the 2015 Status of the Nation's Highways, Bridges, and Transit: Conditions & Performance. HPMS is also used for a multitude of other purposes, not the least of which is apportioning Federal-aid highway monies to the states.

The specific data collection and reporting requirements state DOTs need to comply with are defined in the HPMS Field Manual. FHWA also provides software to submit, validate, and analyze state HPMS data. This software is web-based and is only available to authorized users (typically those staff at a state DOT with responsibilities for reporting HPMS data). The guide for the latest version of this software (i.e., version 8.0) is provided here.

Traffic Data

One of the most important types of data collected for HPMS is traffic data. Of the 70 or so HPMS data elements states are required to report, about a dozen are traffic elements. FHWA’s 2016 Traffic Monitoring Guide is a document designed to help states put together a traffic monitoring program.

Assignment 7-7 (10 points)

Read Chapter 1 and Section 5.3 of the HPMS Field Manual. Submit an M.S. Word document to Assignment 7-7 in Canvas which addresses the following items:

  1. What three data elements are used to divide Federal-aid funds between states? (1 point)
  2. What is the difference between “Full Extent” data items, “Sample Panel” data items, and “Summary” data items? (1 points)
  3. Are states required to report any geospatial data as a part of HPMS? If so, what are states required to report? (2 points)
  4. What is a “traffic monitoring section”? (1 point)
  5. The field guide refers to a “3-year count cycle” and a “6-year count cycle.” What is a “count cycle”? (1 points)
  6. Define AADT, VMT, ATR and AVC (not just the words the letters stand for, but what they mean in your words). (2 points)
  7. Come up with 2 – 4 questions for Jeremy. (2 points)