How to convert cartesian to lat-lon with Topojson?

Question

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:

/usr/local/lib/node_modules/topojson/bin/topojson:303
  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?

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