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The Massachusetts Department of Transportation (MassDOT) GIS Services group provides several data sources that can be useful for those improving OpenStreetMap.

Right to Use

All the data sources provided by MassDOT specify that their "data is in the public domain and therefore can be used by anyone for any purpose." As a courtesy, it should generally be cited as "MassDOT" in changeset sources and comments.

Privacy Policy

There are two privacy policies that one might want to be aware of: First is the Privacy Policy for accessing the main state web site. Also, their data is hosted on ESRI ArcGIS, so when downloading this data using their service their privacy policy also applies:

Data Usage

Note: While the MassDOT data can be a helpful reference, it is not always 100% accurate. Sometimes data points aren't exactly where they would belong in OpenStreetMap, and as with any data source some information may be incorrect or incomplete. It should not be directly used or imported, but only used as a reference alongside other sources like on-the-ground surveying and aerial imagery. Their "license" terms putting the data into the public domain also state:

MassDOT shall not be held liable for any errors in this data. This includes errors of omission, commission, errors concerning the content of the data, and relative and positional accuracy of the data. This data cannot be construed to be a legal document. Primary sources from which this data was compiled must be consulted for verification of information contained in this data.

The easiest way to integrate the data is often using GeoJSON format. In many map editors, you can overlay the GeoJSON feature data and select a feature to see its properties. Click through to MassDOT's description of each dataset for information what properties are available for each feature.

For example, in the iD editor, go to the "Map Data" tab on the right side, click the ••• to the right of "Custom Map Data", and paste in the GeoJSON URL below (and ensure the "Custom Map Data" box is then checked) to see the data on the map. You can then click on one of the nodes to see the detailed properties of it.

Available Data Sources


This contains the location of bridges and culverts within the state. While some of the locations are more exact than others, it can provide some useful information about where stream crosses a road, what the name of a crossing stream is, and whether it's considered a culvert or a bridge.


Highway exit ramp points and numbers. Both the new (2021 renumbering) and old exit numbers are available in the data set.

  • Exits data description
  • GeoJSON:

Traffic Signals

Park and Ride Lots

Parking lots owned or operated by MassDOT.

Electric Vehicle Charging Stations

Note that this only includes MassDOT-owned charging stations.

Bus Stops (except MBTA)

Bus Routes (except MBTA)


→ See the MBTA page for resources on getting data for MBTA stops and routes.


This contains all mile markers on numbered routes throughout the state. Warning: this is a very large file (well over 100 MB) and will not work well within a browser-based editor like iD.

More Sources

Other data is also available to reference, some MassDOT sites to look through include:

Previous imports

Some data from the MassDOT (and its predecessor, the Executive Office of Transportation), particularly the state road inventory, were initially imported into OpenStreetMap in 2007, with some additional fixes and updates added since then. Some of these weren't done in the way that such an import would be accomplished nowadays: in particular source tagging was done on the nodes and ways rather than on the changesets.