Nationwide Horizontal Curve Inventory

Horizontal curves are indispensable for roadway safety and mobility. Public transportation agencies are exploring efficient and effective approaches to better understand the spatial location, geometrical attributes and conditions of the horizontal curves within their extensive networks of road jurisdiction. With the wide availability of global positioning system (GPS) and geographic information system (GIS) data, some efforts have been made to develop automated algorithms for identifying horizontal curves from GPS trajectories or GIS basemaps. While these methods have shown promising results, they have not been validated or practically applied over large testing datasets with complicated road network connections.

In this study, the research team will continuously process the networks nationwide using the publicly available GIS basemaps, to cover the entire Numbered Highway system in the United States. This gallery of horizontal curve inventories shows the current availability of the results. Please click the link underneath the map for more information. Mileage Completed – 105,343.66 Miles, Mileage under QA/QC – 90,745.10 Miles (as of 2019/8/9).

AL AK AZ AR CA CO CT DE FL GA HI ID IL IN IA KS KY LA ME MD MA MI MN MS MO MT NE NV NH NJ NM NY NC ND OH OK OR PA RI SC SD TN TX UT VT VA WA WV WI WY DC

StateRoutesCurvesGCSPCSLinkStatus
Alabama25713,650EPSG 4269EPSG 26929Basemap ThumbnailCompleted
Alaska160EPSG 4269EPSG 26931Basemap QA/QC
Arizona1499,624EPSG 4269EPSG 26948Basemap ThumbnailCompleted
Arkansas1,90538,616EPSG 4269EPSG 26915Basemap ThumbnailCompleted
California25436,944EPSG 6318EPSG 6416Basemap ThumbnailCompleted
Colorado296EPSG 4269EPSG 26913Basemap QA/QC
Connecticut40811,983EPSG 4326EPSG 3857Basemap ThumbnailCompleted
Delaware701,807EPSG 4269EPSG 26957Basemap ThumbnailCompleted
Hawaii140EPSG 4152EPSG 3750BasemapQA/QC
IllinoisBasemapOngoing
IndianaBasemapOngoing
Kansas2054,490EPSG 4269EPSG 26977Basemap ThumbnailCompleted
Kentucky3,380EPSG 4269BasemapQA/QC
Maine1317,518EPSG 4269EPSG 26919Basemap ThumbnailCompleted
Maryland47912,095EPSG 4269EPSG 26985Basemap ThumbnailCompleted
Massachusetts17113,422EPSG 4269EPSG 26986Basemap ThumbnailCompleted
Minnesota181EPSG 4269EPSG 26915BasemapQA/QC
MississippiBasemapOngoing
MissouriBasemapOngoing
Montana298EPSG 4269CustomBasemapQA/QC
NebraskaBasemapOngoing
Nevada249EPSG 4269EPSG 26911BasemapQA/QC
New Hampshire12510,639EPSG 4269EPSG 32110Basemap ThumbnailCompleted
New Jersey1514,994EPSG 4269EPSG 3424Basemap ThumbnailCompleted
New York848EPSG 4269EPSG 26918Basemap QA/QC
North CarolinaBasemapOngoing
North Dakota109EPSG 4269EPSG 102721Basemap QA/QC
Ohio570EPSG 4326EPSG 3857BasemapQA/QC
Oklahoma259QA/QC
Pennsylvania50547,107EPSG 4269EPSG 32128Basemap ThumbnailCompleted
Rhode Island662,048EPSG 4269EPSG 32130Basemap ThumbnailCompleted
South CarolinaBasemapOngoing
TexasBasemapOngoing
Utah233EPSG 4269QA/QC
Vermont10410,542EPSG 4269CustomBasemap ThumbnailCompleted
WashingtonBasemapOngoing
West Virginia516EPSG 4269EPSG 26917ThumbnailQA/QC

Definition – The curve inventory results will include all the properties that are necessary for safety analysis or other applications. Depending on different basemap formats, the curve inventory will at least include the following attributes and represented based on the corresponding linear reference system. 

Citation – If the results and the datasets are used for academic publication, please appropriately cite the basemap data source (as listed in the corresponding result section) and the following paper in the publication.

Ai, C. and Tsai, Y. (2015). ”Automatic Horizontal Curve Identification and Measurement Method Using GPS Data.” ASCE Journal of Transportation Engineering, 141(2), 04014078

Wang, Y., Ai, C., and Qiu, S. (2019). “Development of A Nationwide Horizontal Curve Inventory Using Open GIS Data.” International Conference on Transportation & Development 2019, Alexandria, VA.

Wang, Y., Ai, C., and Qiu, S. (2020). “Development of A Large-Scale Horizontal Curve Inventory for Safety Analysis Using Open GIS Data.” 99th Transportation Research Board Annual Meeting (Under Review).

Disclaimer – All the results and information for the horizontal curves on this website were derived ONLY for academic research purposes. The Ai Research Group derived the results based on the publicly available data at the time of processing, but it does not guarantee any changes in the data sharing the policy of the hosting agencies. Please contact the data hosting agencies for more information. The copyright of the data belongs to the data hosting source as the copyright text indicates. The Ai Research Group has internally evaluated and validated the results before it releases any results on this website, but it does not guarantee the quality and the accuracy of the results, nor imply any of its potential applications. Please use the data and the results at your risk, and please use the data ONLY for academic purposes.