1. Calculating Travel-Time …vector to raster conversion
Analysis grid superimposed
2D Street Grid
Note that a 100 row by 100 column analysis grid (10,000 cells) is superimposed on the street data and those cells containing a road are assigned a friction value representing the typical time to traverse each location– primary streets (red) = 8.5 seconds; secondary streets (blue) = 25.5 seconds.

2. Calculating Travel-Time …street types as relative barriers
3D Street Grid
2D Street Grid
Note that the street pattern can be displayed as 2D and 3D plots. The street pattern can be conceptualized as a canal network that connects Kent’s Emporium to its customers.
Kent’s Emporium

3. Calculating Travel-Time …”splash” 0-10 cells = 0 to 1.4 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-10
2D TTime_0-10
Note that the distance “waves” begin to move away from Kent’s Emporium along the “canal” pattern (streets) like ripples from a rock tossed into the water. The distance waves accumulate the time it takes to cross each grid cell– considering the relative impedance for primary (8.5sec) and secondary (25.5sec) streets.

4. Calculating Travel-Time
…0-20 cells = 0 to 2.8 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-20
2D TTime_0-20

5. Calculating Travel-Time
…0-30 cells = 0 to 4.3 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-30
2D TTime_0-30

6. Calculating Travel-Time
…0-40 cells = 0 to 5.7 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-40
2D TTime_0-40

7. Calculating Travel-Time
…0-50 cells = 0 to 7.1 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-50
2D TTime_0-50

8. Calculating Travel-Time
…0-60 cells = 0 to 8.5 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-60
2D TTime_0-60

9. Calculating Travel-Time
…0-70 cells = 0 to 10.0 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-70
2D TTime_0-70

10. Calculating Travel-Time
…0-80 cells = 0 to 11.4 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-80
2D TTime_0-80

11. Calculating Travel-Time
…0-90 cells = 0 to 12.8 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-90
2D TTime_0-90

12. Calculating Travel-Time
…0-100 cells = 0 to 14.2 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-100
2D TTime_0-100

13. Calculating Travel-Time
…0-110 cells = 0 to 15.7 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-110
2D TTime_0-110

14. Calculating Travel-Time
…0-120 cells = 0 to 17.1 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-120
2D TTime_0-120

15. Calculating Travel-Time
…0-130 cells = 0 to 18.5 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-130
2D TTime_0-130

16. Calculating Travel-Time
…0-140 cells = 0 to 20.0 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-140
2D TTime_0-140

17. Calculating Travel-Time
…0-150 cells = 0 to 21.4 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-150
2D TTime_0-150

18. Calculating Travel-Time
…0-160 cells = 0 to 22.8 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-160
2D TTime_0-160

19. Calculating Travel-Time
…0-170 cells = 0 to 24.2 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-170
2D TTime_0-170

20. Calculating Travel-Time
…0-180 cells = 0 to 25.6 minutes
Base cell = 8.5sec = .1424min
3D TTime_0-180
2D TTime_0-180

21. Calculating Travel-Time
…0-180 cells = 0 to 25.6 minutes
Base cell = 8.5sec = .1424min
2D TTime_0-180
Results displayed in a Desktop Mapping system (raster to vector)
Note that of the 10,000 cells comprising the analysis grid, 4123 do not contain a road. Of the 5877 cells with a road, 3014 locations (a little over 50 percent) are 0 to 70 effective cells away, or about 10 minutes from Kent’s Emporium (non-shaded area of the summary table)

22. Calculating Travel-Time
For more discussion on travel-time calculation and its applications, visit…
…educational software for hands-on experience in creating and using travel-time maps and other grid-based map analysis
…online book discussing travel-time concepts, procedures and considerations (Topics 5, 6, 13,14 and 17), as well as other grid-based analysis techniques
…also see Papers/Presentations Online Papers, select “Understanding Effective Distance and Connectivity”