I've been following the "Let's Make a Map" tutorial by mbostock about converting files for use for d3.js. I have been able to get things working with files from Natural Earth, but when trying to convert the shapefiles from the MBTA website (http://www.mass.gov/anf/research-and-tech/it-serv-and-support/application-serv/office-of-geographic-information-massgis/datalayers/trains.html), which stores lineshapes with cartesian coordinates and arcs (with topojson -t_srs EPSG:4326...), I get an error:

  var i = file.indexOf("=");
TypeError: Object true has no method 'indexOf'

I get this even trying different values for EPSG such as 26986. How can I represent these files in d3 (alongside other topojson files that use lat/lon), or convert the coordinates to lat/lon?

  • Looks like a bug in topojson to me. file is being set to the wrong type.
    – Nathan W
    Dec 14, 2013 at 22:21

1 Answer 1


The topojson command has no parameter -t_srs, it is ogr2ogr what you want to use:

ogr2ogr -f GeoJSON trainsGeoJSON.json TRAINS_RTE_TRAIN.shp -s_srs EPSG:26986 -t_srs EPSG:4326

Then convert to topojson format (as described here):

topojson -o trainsTopojson.json trainsGeoJSON.json 
  • Thank you! I had tried using -t_srs with ogr2ogr but had not specified the source with s_srs.
    – arilaan
    Dec 15, 2013 at 6:08

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