To calculate the time it takes to drive on a road, the speed a person drives must be taken into consideration. This is the cornerstone of improvements to the routing technique. While the speed data we use currently may not be 100% accurate, it is a good starting place, and a good baseline to test our improvements.
The type of road we drive on is a good indicator of the speed. the TIGER data provides us with some information about the road type. For instance, A1? roads are interstates, A2? are US highways, etc. I will provide the speeds i'm using, but to read more about the road types, check out this link.
The table for speeds we are using can be created with this:
CREATE TABLE [dbo].[speeds](
[CFCC] [nchar](3) NULL,
[speed] [int] NULL
) ON [PRIMARY]
the data in the table is as follows. I manually typed it in:
A11 65
A12 65
A13 65
A14 65
A15 65
A16 65
A17 65
A18 65
A21 55
A22 55
A23 55
A24 55
A25 55
A26 55
A27 55
A28 55
A31 45
A32 45
A33 45
A34 45
A35 45
A36 45
A37 45
A38 45
A41 35
A42 35
A43 35
A44 35
A45 35
A46 35
A47 35
A48 35
A51 NULL
A52 NULL
A53 NULL
A60 35
A61 15
A62 25
A63 35
A64 15
A65 NULL
A70 NULL
A71 NULL
A72 NULL
A73 15
A74 15
I decided that on Interstate Highways people drove an average of 65MPG, US highways were 55, State roads were 45, local roads were 35, and assorted other roads were 15MPH. The other road types are left NULL but you can fill in any number you want.
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