Technical Blog Post
Fun with Linear Assets Part 2
I'm back again this week with part 2 of my three part series on linear assets. Today we'll take a closer look at a usage case and see how the functionality of linear assets can make life much easier for you....
Here's the scenario:
- A public works department for a US state is responsible for the maintenance and repairs on a local highway
- Dispatcher and Planners need to easily define and direct work crews to very specific segments of the highway that needs repairs
- Features, relationships and attributes need to be defined along the highway to help locate where the work needs to be done
- Because the highways may intersect with other highways or roads that cross multiple districts or cities, the linear asset may require aliases (Route 95, Interstate 95, the Maine Turnpike etc.)
- The dispatchers and planners need to be able to graphically view the highway and the many components that comprise it
For this example we'll look at our Route 95 North highway.....
We can see from the screenshot above that linear referencing details related to our highway are displayed. We also know that the highway extends northbound for 109.7 miles. Someplace on our highway we have multiple reports of vehicles being damaged with flat tires because a major pot hole and crack in the pavement that was left from the previous winter's snow plowing.
If we look at the Features tab of the asset we can see multiple segments and markers that make up the highway. We know that the reports are say that the damaged section of the highway is located where Interstate 95 North intersects with Maryland Route 414. From looking at the list of features that make up this highway we know that the intersection takes place 4.3 miles from the start of the highway. We can use this as a reference to get our work crew to the right place to make repairs.
If we look at this feature we can see additional info about the intersection: it's start / end point as well as it's Y and Z offsets. The Y offset is the perpendicular distance from this linear asset. For example, if a sign is 10 feet to the right of the road, the Y-Offset is 10 feet. This value is measured from the Y Reference Point and can be positive (right) or negative (left). The Z reference is the distance above or below the linear asset. For example, if a sign is 10 feet above the road, the Z-Offset is 10 feet. This value is measured from the Z Reference Point and can be positive (above) or negative (below). The Z reference can be useful when dealing with things like bridges, power lines or drainage ditches. These values give the planners and dispatchers the ability to define very specific locations where they need the crews to work. We also see that the Z reference indicates that this intersection is at the surface of the road rather than above or below it.
If we move over to the Specifications tab, we can see various attributes related to this highway that are applied to the linear asset when we use the ROADS classification. This gives us even more information that we can use to define segments of the highway. This is where we can define alternate names for the highway, districts it runs through, demographic areas, counties etc. This can be helpful to determine who is responsible for work, who's budget is effected, and even what time of day it might be best to do the work. If we know that the work is to take place in an urban area as opposed to a rural area it might effect when we want to schedule the work so we can avoid traffic during rush hour for example. From the screenshot if we look at the start / end points of the attributes, we can tell the intersection that we're looking for exists on a stretch of the highway that is known as the Capital Beltway, it's suburban, and that it's in Prince George county.
If you scroll to the lower section of the Specifications tab, you can actually look at these various attributes graphically to see exactly where they exist on the highway relative to the overall length of the asset.
Now that we've been able to determine where the repairs need to be made, we can use this information to create a work order. For starters we'll add our highway to the asset field on the work order......
This action will dynamically cause linear referencing data to be displayed to allow us to easily direct the crew to the damaged pavement.....
Now that we've created a work order using the linear references for our highway, we can go back to the Specifications tab and see that our work order is now displayed graphically on the highway. On a side note, any of the dots, lines, features, segments etc. on the graph can provide more info by floating your mouse over them. In this case we can see that our work order has been created, we can see the status and we can see exactly where on the highway the work is to be done.
Well that's a very brief example of how linear assets can be used when dealing with roads and work that needs to be done on them. In part 3 of the series we'll take a look at some of the other possible uses for linear assets.
Until next time, thanks for reading and be safe out there! Later!