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Author Topic: Street data with speeds  (Read 1299 times)

93ToyTruck

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Street data with speeds
« on: February 21, 2015, 09:07:12 AM »
I'm using Tiger as my street data source but the classification attributes don't provide enough detail. A two lane residential road has the same classification as a six lane thoroughfare. Is there another data source that provides more detail on the type of street or speed?


Boyd

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Re: Street data with speeds
« Reply #1 on: February 21, 2015, 09:20:02 AM »
Check your state/county GIS resources. The dept of transportation probably has some official data available for download.

Here in NJ, the Dept of Transportation has their own road shapefiles and I have switched to them from TIGER. They show all the official road classifications and the county route numbers too, which are rarely found in the TIGER data. I like using route numbers instead of street names when possible, since the numbered icons appear on the GPS screen through a much greater range of zoom levels than street names.

The NJDOT data is also supposed to be accurate to within one foot. Each road is a continuous track instead of many little segments - might be a disadvantage for some mapmakers, but I find it a lot easier to deal with and I don't create routable maps.

Downside is that they don't include very many dirt roads and some newer developments aren't mapped, so I continue to use TIGER for these.

I have also used OpenStreetMap shapefiles recently for NY and PA. They are a bit of a mixed bag. Some of the roads are classified better than TIGER, but not consistently. The problem with both of these sources is, as you suggest, that they mostly group roads into three types - interstates, major highways and minor roads. This completely ignores designated county routes which really should have their own class. And unpaved roads are rarely differentiated from paved roads. The NJDOT data fixes these problem for me, so maybe your state(s) have something comparable?
« Last Edit: February 21, 2015, 09:40:03 AM by Boyd »

93ToyTruck

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Re: Street data with speeds
« Reply #2 on: February 21, 2015, 03:51:30 PM »
I'm in California. The website doesn't have anything to download but it looks like I can request  "unofficial" data that has greater classification. I'll give that a try.

Nice observation on routing numbers. I hadn't thought of that. I like using them because they change less frequently than street names.

Long tracks, good. Small segments, bad. They drive me nuts.

maps4gps

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Re: Street data with speeds
« Reply #3 on: February 24, 2015, 12:04:50 PM »
Quote
...and the county route numbers too, which are rarely found in the TIGER data.
   Not exactly true. 

One of the files for each county is 'featurename'.  A dbf file which contains a record for each alternate spelling/miss-spelling, and/or prefix and/or suffix for each feature; including route numbers.  Unfortunately not in any discernible order; even the name/number in the geographic shape file may not be first (at least the last time I checked - about 5 years ago).   Many road 'segments' have more than one route number and are sometimes also named and occurred in the files in no hierarchal order (as I,US,ST,CO, etc).  I never found a way to include more than one number in the shield symbol.