# How to calculate time to destination using Raster/Spatial Analyst

How to use rasters/Spatial Analyst to determine time to destination? I used this tutorial, (https://www.youtube.com/watch?v=DwIP17YXQUY) but my times don't make sense.

My workflow:

• Travel on highway was assigned 100km/hr

• Travel on land was assigned 5km/hr

• I converted road speed and land speed to seconds/100m (how many seconds does it takes to cross 100m cell; roads take 4 seconds/100m; travel on land takes 72 seconds/100m)

• I combined the land and roads into one raster using the seconds/100m as the cell value (my resulting raster has two cell values 72 and 4, first image below)

• I used this raster as the input for Cost Distance tool (cost in this case is the time it takes to cross a cell), I used a point (green star on the map below) as a destination

• I thought the resulting Cost Distance raster would give me time to destination, but It’s way off (it tells me 1.2 hours to travel 30km on a highway)

Map below, shows my cost raster (I have 2 cost times 72 for land and 4 for highway, this is the input for Cost Distance tool):

Map below, shows my Cost Distance output around the destination. Traveling on land away from destination somewhat makes sense, it increases by 7200 with each cell (2 orders of magnitude off?); Travelling on road doesn't make sense, it inconsistently increases by 1900-3200.

Am i doing something wrong or is this method not valid for time to destination calculations?