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Engine Works

Under the hood of Alteryx: tips, tricks and how-tos.
Rob_McFadzean
Alteryx Alumni (Retired)

This blog post is referring to functionality that will be in our next major release. Beta users can preview this feature later this year with the Q3 2011 release of the Alteryx Drivetime engine. Please send an email to products@alteryx.com if you are interested in participating in our Beta program.

 

Coming in Alteryx 7.0, the Alteryx drivetime engine (Guzzler) will be utilizing the improved 'Multi Start' methodology. Much of the improvement is in the initial nodal search Guzzler utilizes which allows for more accurate drive time and drive radius calculations.

 

Multi Start methodology will be standard Guzzler methodology for Alteryx 7 as it will allow for much more precise drive time calculations.Users will see more realistic drive times with the new enhancements which now incorporate off road speed, mid segment start and end points as well as multiple searches for potential start points on the road network.

 

Improvements with Multi Start:

 

  • The old methodology joined the road segments at the start and end points; the new methodology is able to join the segment not only at start and end points, but also mid segment.
  • Multi Start is able to explicitly identify limited access roads. Roads which were limited access are now seen as such and Guzzler is able to jump on the road network only where possible on these limited access roads.
  • "Off road" travel time now counts towards the drive time in instances where the "Off Road" travel time is necessary. Previous methodology did not count any of the "Off Road" drive time in the drive time calculation.
  • Multiple Starting Points: Guzzler is able to determine multiple starting points which are rated of similar quality and is able to start from each one of these start points simultaneously.

 

One advantage of this new methodology is that instead of finding the closest starting node and then using it to determine the drive time; Guzzler will now search for other nodes that are possible starting nodes, these start nodes may be of much better quality. A specific example of this is where Guzzler previously had found the starting node in a suburban neighborhood and missed a better starting node which would have led right onto a limited access highway only because it was a little further than the first node. In this rare case, Guzzler was unable to get onto a close highway using a different start node.

 

With Multi Start, off road speed is now counted in the drive time, this means that if a drive route goes off road at a point it will also be counted in the drive time, whereas before Guzzler would teleport within an explicit setting distance to the start point. In these cases the distance and trade area captured would be less because more time had elapsed with less captured distance. See the images below.

 

 

Notice how Multi Start (right image) captures the start point and has a smaller total drive radius for the same 3 minute drivetime specification.

 

Likewise in drivetime mode the start and end points are calculated in the total time and distance as shown by the below calculations.

 

Multi Start on the left shows the "Off Road" calculation as part of the drive time calculation whereas, the original Guzzler on the right does not.

The Multi Start methodology is able to calculate nodes mid segment rather than having to go to the end of the node.

 

Much of this is emphasized in the 5min Drive Radius' below:

 

In the above diagram the "Old Methodology" is used which makes it all the way to Slater Avenue in the 5 minute drive time. This is as a result of finding a new segment which is counted until the end of the node in the old methodology.

 

Multi Start in the below diagram only makes it to Warner Avenue in the same 5 minute drivetime because the new methodology is able to stop mid segment and does not have to count the last segment reached until its very end. This is more acurate.

 

The Multi Start methodology is able to properly determine limited access roads; previously Guzzler would start calculations on limited access roads without first determining how to access those roads. In being able to determine whether a road is classed as limited access, the Multi Start methodology is able to find the appropriate route to gain access to this road class and then calculate the rest of the drive route accordingly.