S Postmile Routes (Spur State Highways)

[Max Rockatansky]

I can't seem to find a good way to account for all these aside from digging around in the Caltrans Postmile Tool.  Off the top of my head, I'm aware of 40S on Main Street in Barstow, 10S on the San Bernardino Freeway, 5S on the Colorado Street Freeway Extension and 880S in Oakland.  Is there a master list of S Postmile Highways out there or is anyone aware of others I just haven't tracked down yet?

[cahwyguy]

Go to the State Highway Lines GIS database: https://gisdata-caltrans.opendata.arcgis.com/search?tags=Highway
Go to the Filter Data symbol
Select a route suffix of "S"
Look for what shows up on the map.

[cahwyguy]

Based on that data: There is no 40S. There are two I-5S segments (One in Santa Clarita), and 3 Route 178S segments, and one 15S segment that you missed. .

[Max Rockatansky]

Noted on the data linked above.  The I-5S in Weldon Canyon/Santa Clarita I guess is the Truck Bypass. 

That said, part of Main Street in Barstow was never relinquished.  It was retained the connected for westbound I-40 to northbound I-15.  It shows up as Route 40 with S Postmiles with the Postmile Tool as S0.000-S0.794.

[RZF]

I'm guessing, should the Colorado Freeway have been given a separate state route number and not the 5S designation if its plans were carried out?

[pderocco]

Go to the State Highway Lines GIS database: https://gisdata-caltrans.opendata.arcgis.com/search?tags=Highway
Go to the Filter Data symbol
Select a route suffix of "S"
Look for what shows up on the map.

When I go to that URL, I don't see "Filter Data", anyplace to select a route suffix, or a map. However, if I select the All Roads dataset, I see a map, and a filter icon, but I still don't see how to select a route suffix, or anything useful for searching on. Or am I misunderstanding what this site allows you to do?

[cahwyguy]

Go to the State Highway Lines GIS database: https://gisdata-caltrans.opendata.arcgis.com/search?tags=Highway
Go to the Filter Data symbol
Select a route suffix of "S"
Look for what shows up on the map.

When I go to that URL, I don't see "Filter Data", anyplace to select a route suffix, or a map. However, if I select the All Roads dataset, I see a map, and a filter icon, but I still don't see how to select a route suffix, or anything useful for searching on. Or am I misunderstanding what this site allows you to do?

Go down near the bottom of that page. You'll see a database called SHN Lines (State Highway Number Lines). I think the direct URL is https://gisdata-caltrans.opendata.arcgis.com/datasets/77f2d7ba94e040a78bfbe36feb6279da_0/explore

When you click on that, you'll see a box with four icons. The top most is an i in a circle. Below that is something that looks like a funnel. That brings up the filter option. In this database (you'll need to zoom in), you can click on any highway segment and see its details.

[cahwyguy]

That said, part of Main Street in Barstow was never relinquished.  It was retained the connected for westbound I-40 to northbound I-15.  It shows up as Route 40 with S Postmiles with the Postmile Tool as S0.000-S0.794.

This, friends, is an important distinction. There are routes with S suffixes, and there are routes with S prefix postmiles, and they are different things. Using the same GIS database, you can filter for the S Postmile Prefix. The gives, in addition to the Route 40 segment, some Route 4 segments, some Route 178 segments (which are both S Postmiles AND 178S), US 101 (old proposed I-105), and I-10 (old proposed I-110, not the busway). Route 7 also has some S miles, as does Route 38 in Redlands. Route 18 has a few.

Daniel

[cahwyguy]

I'm guessing, should the Colorado Freeway have been given a separate state route number and not the 5S designation if its plans were carried out?

If plans were carried it, it would have been part of Sign Route 134. But a different final routing was adopted, leaving that spur orphaned. As it served as a connector to I-5 from Glendale, they opted to keep it in the state highway system, but it was long enough they couldn't treat it as a simple offramp -- hence the I-5S designation.

[Max Rockatansky]

I'm guessing, should the Colorado Freeway have been given a separate state route number and not the 5S designation if its plans were carried out?

If plans were carried it, it would have been part of Sign Route 134. But a different final routing was adopted, leaving that spur orphaned. As it served as a connector to I-5 from Glendale, they opted to keep it in the state highway system, but it was long enough they couldn't treat it as a simple offramp -- hence the I-5S designation.

It was part of the original CA 163 for a brief period.  Out of all these routes we are discussing it probably is the one closest to meriting a stand-alone designation.

[pderocco]

Go to the State Highway Lines GIS database: https://gisdata-caltrans.opendata.arcgis.com/search?tags=Highway
Go to the Filter Data symbol
Select a route suffix of "S"
Look for what shows up on the map.

When I go to that URL, I don't see "Filter Data", anyplace to select a route suffix, or a map. However, if I select the All Roads dataset, I see a map, and a filter icon, but I still don't see how to select a route suffix, or anything useful for searching on. Or am I misunderstanding what this site allows you to do?

Go down near the bottom of that page. You'll see a database called SHN Lines (State Highway Number Lines). I think the direct URL is https://gisdata-caltrans.opendata.arcgis.com/datasets/77f2d7ba94e040a78bfbe36feb6279da_0/explore

When you click on that, you'll see a box with four icons. The top most is an i in a circle. Below that is something that looks like a funnel. That brings up the filter option. In this database (you'll need to zoom in), you can click on any highway segment and see its details.

Thanks. What I missed was that "State Highway Lines" was the name of one dataset. I assumed that was what the site was.

That's pretty interesting. The suffixed routes seem to be almost entirely a SoCal thing. But I don't understand why 178S in Bakersfield isn't called 178U instead.

[Max Rockatansky]

178 having a spur I get.  There is no direct ramp connection from eastbound 178 onto southbound 204/Union or from northbound 204 onto what was westbound 178 in downtown.