In 2009, The Ohio Department of Transportation, with cooperation from the Ohio-Kentucky-Indiana Regional Council of Governments (OKI) and Miami Valley Regional Planning Commission (MVRPC) undertook a GPS-based household travel survey as a research project AND as an updated dataset for OKI to use.
As far as a research project went, the public agency staff learned a lot about performing a GPS-based household travel survey. However, at the end of it all, OKI was left with a dataset of questionable quality that was largely determined by methods that were not documented to ODOT, OKI, or MVRPC. This was the case when the project concluded in the Spring of 2011.
As far as usability of the data, OKI attempted to use the data for travel model supply calculations (trip generation, distribution, and mode choice) in 2012-2014, culminating with a peer review in April of 2014. It was found that the dataset was deficient in many ways and the models estimated from said data were also deficient. As such, OKI staff is endeavoring to re-work the data using the latest research outlined at the 2014 Innovations in Travel Modeling Conference and NCHRP Report #775 (AKA NCHRP 08-89).
The programming work included is initially to process the GPS files that were provided by the subconsultant that performed the GPS analysis. No data is included in this due to privacy. It is expected that others have their own raw GPS files to use. The program imports files, reprojects the data to NAD83 State Plane Ohio South Feet, computes time, speed, heading/bearing, and clustering at 100, 250, and 500 feet. The data is then saved to the hard drive (this ideally will prevent memory overruns). In addition, there are parts of the processes to detect stops and perform some smoothing on the GPS points (based on [1]).
The following are tasks that need to be included:
- General data cleaning and calculations
- Trip End Detection
- Mode Change Detection
- Mode Imputation
- Purpose Imputation
This project uses Apache Maven. Note that the author is new to Apache Maven and would be happy with any help or best practices.
Download from maven.apache.org Copy files somewhere and get path to bin folder, add to system path Set JAVA_HOME variable to correct Java location Open a command prompt and run "mvn --version" to test
This is licensed under the Apache 2.0 License. See the LICENSE.txt file included in the source code.
[1] Schuessler, N., and K. W. Axhausen. "Processing GPS Raw Data Without Additional Information". TRB 2009.
[C] Huxtable, Jerry. JH Labs Projection Library. http://www.jhlabs.com/java/maps/proj/index.html. Licensed under Apache License 2.0.
[C] Hexiong?. JDBF Java reader and writer library for DBF database files. https://code.google.com/p/jdbf/. Licensed under Apache License 2.0.