Future Interstate designation along California State Route 99

Minh_Nguyen · December 31, 2025, 8:39pm

There’s an ongoing dispute between @Flap_Slimy_Outward and several other mappers (including myself) about whether to model the freeway segment of California State Route 99 between Wheeler Ridge and Stockton as both Future Interstate 7 and Future Interstate 9. Changeset 175,784,654 changed ref=CA 99 to ref=CA 99;I 7–9 FUT along each way and added them to network=US:I:Future ref=7–9 relations. This changeset was reverted last night. The contention is that, at this point, any sort of numbered Interstate tagging is premature speculation. Because the mappers involved continue to disagree, we’d like confirmation from the broader community about what should be done about this designation, if anything.

For context, most future Interstate corridors are occasionally marked by special signs, which may or may not display a number. This is our usual criteria for tagging fut_ref=* or network=*:Future. However, no one has come forward with any evidence of such a sign in California.

In any case, the signs are informative, a consequence of federal legislation and active planning by the state highway department. In 2005, Congress designated the segment of Route 99 in question as a future Interstate corridor but did not associate it with a specific Interstate Highway number. In federal legislation, this corridor is only known as the California Farm-to-Market Corridor.

The provisional designation expires in 2030, giving Caltrans until then to completely upgrade the corridor to Interstate Highway standards and formally apply to AASHTO for Interstate designation. In a business plan at the time, Caltrans estimated that this would cost the state an additional $14–19 billion. Any federal funds would have to come out of the budget for California’s other projects in the National Highway System.

In 2006, the California Department of Transportation put out a master plan for Route 99 that called for upgrading it to a standard freeway and eventually pursuing Interstate designation:

Interstate designation, under the current proposal, would apply to the 260-mile (420 km) segment between the junction of State Route 99 with I-5 south of Bakersfield to I-5 in Stockton using State Route 4 as the connector to I-5. Since there is an I-99 route currently in existence in Pennsylvania, it is anticipated that should designation be granted, the Route 99 designation would become I-7 or I-9 to satisfy Interstate numbering convention.

Ever since then, roadgeeks have salivated over this possibility. Both the English Wikipedia and the AARoads Wiki cite this single passage as evidence of a future I-7 or I-9. It is a frequent topic of discussion on roadgeek forums.

I’ve yet to come across any mention of either I-7 or I-9 in any other Caltrans document. The 2005 business plan was updated in 2013 and 2020 to remove any mention of possible Interstate designation, consistent with revisions to the Interregional Transportation Strategic Plan that deemphasize freeway construction in favor of projects like California High Speed Rail. Caltrans has finished grade-separating every interchange along the corridor, but controlled access is only one of many elements of Interstate Highway standards. The business plan no longer tracks Interstate Highway standards compliance, so it’s unclear what remains to be done before 2030.

The California State Legislature would also have to amend the California Streets and Highways Code to renumber the highway from Route 99 to either Route 7 or Route 9, and in turn renumber the existing Route 7 or Route 9 to something else. Unlike in some other states, California state law does not allow for an Interstate n that’s distinct from the statutory Route n. No bill has come before the legislature to renumber these routes.

At no point did Caltrans ever state a preference between 7 and 9, which presents a problem for the route tagging scheme. We only have the capability to express that a highway is part of two different routes concurrently, or that a single route is known by two different numbers simultaneously. But we don’t have an established tagging scheme to express two different possibilities with equal probability. The disputed changeset chose “7–9”, with an en dash as a separator, which has no precedent in OSM.

SD_Mapman · December 31, 2025, 9:43pm

If there’s no signage, I don’t see any point. It sounds like the Interstate designation was only mentioned one time 20 years ago, and Caltrans doesn’t seem to care. I say leave it off, and only worry about updating the ref tags and adding the route relation if the signage change ever happens.

ZLima12 · December 31, 2025, 10:04pm

I think that the only appropriate way for something like this to be mapped is as a route relation in the proposed namespace. network=US:I:Future should be for roads that have the future Interstate signage, and fut_ref on ways should only be used when there is more certainty that the ref will actually get assigned.

Assuming the aforementioned route relation is to exist, I think I would prefer the use of a semicolon to separate the 7 and 9 in ref. It’s not ideal, since it is usually interpreted as “and” rather than “or”, but for a proposed route this isn’t that big of a deal.

Carnildo · December 31, 2025, 10:10pm

This seems like a straightforward application of the “on the ground” rule: if there’s no signage calling it a future interstate, it doesn’t get mapped as one in OSM. Contrast with “Future US-395” in Spokane, which has both navigation signage and reassurance markers displaying that name.

pussreboots · December 31, 2025, 10:17pm

I have seen Caltrans plan interstates only to have the local community vote to stop them enough times to feel that 99 should be left as 99 in that area until actual work begins.

n76 · December 31, 2025, 10:40pm

@pussreboots In general I agree that CalTrans planned freeways often run into community opposition. In the case of CA-99 (former US-99), to my non-road engineer eyes it already is a freeway from Stockton south to the join with I-5. Dual carriageway, Interstate standard lane widths, and limited access the entire way. I am not sure what upgrades CalTrans thinks it needs to bring it to Interstate standards as it seems to meet of exceed the standards for many Interstates I have driven on. My guess is that unless turning it into an official Interstate would in some way allow California to get more Federal money, CalTrans has no real reason to pursue whatever the upgrades are and it will stay a state highway indefinitely.

But to the top level question, my take is “no signs on the ground” means it shouldn’t be in OSM. If someone really, really insists it be in OSM then I agree with @ZLima12 that it should just be a route relation using a future namespace.

Minh_Nguyen · December 31, 2025, 11:42pm

If I had to guess, one obstacle would be all the short RIRO interchanges that remain unchanged since the 1970s. RIRO interchanges rarely occur on the Interstate system due to safety concerns. Before Caltrans could redesignate a stretch of State Route 17 near San José as Interstate 880, they completely rebuilt several interchanges of this same design. Some of the RIRO ramps along Route 99 have at least been extended, but I don’t know if that’s enough to satisfy the design speed criteria in the Interstate Highway standards.

There are two common tagging conventions for not-yet-designated route relations in the U.S.:

network=US:I:Future is for routes that have Future Interstate Corridor signage. This is what the disputed changeset used.
Some planned U.S. Bicycle Route corridors are tagged route=bicycle state=proposed. This troll tag is only used on recreational routes for historical reasons; data consumers don’t know to look for it on a highway route.

In some other countries, mappers have started using proposed:route=* instead of relying on state=proposed. If we restore the future Interstate corridor relation, this would be the safest option for preventing navigation applications from sending drivers on a wild goose chase. The proposed:*=* namespace is intended for things that would get recreated anyways if we delete them. Roadgeeks will be tempted to sneak I-7 and/or I-9 into OSM for another five years, so there is some merit in the idea of a nominal placeholder.

Then there’s the question of the route’s identity. This proposed route has no number yet, just an obscure name that has only ever been uttered on the floor of Congress. As long as it’s tagged proposed:route=road network=US:I, then I suppose we can set the name as “California Farm-to-Market Corridor”, but we’d need to avoid any sort of ref tag, which would be misleading.

idkwhatname2use · January 1, 2026, 5:07am

To my knowledge, CA 99 had some at grade intersections when this future interstate was speculated by the department. Either way, Caltrans doesn’t make policy, the California Legislature does, and they don’t seem to care.

Also, this topic seems to be treading into the same territory as to whether abandoned railroads whose right of ways don’t exist anymore should be mapped or not… hell I think those abandoned routes have more legitimacy to be mapped on OSM than this since at least they EXISTED at one point without speculation…

Minh_Nguyen · January 1, 2026, 6:38am

I figure the numbers are the main motivation for this mapping. At most we allow the proposed route but not the numbers, but in that case, it isn’t clear that anyone will want to map the proposed route anyways. It would be pointless even to the few people who care about this provisional designation.

The same master plan posited a historical designation for Route 99. At least it would be contiguous, unlike some of the state’s other historic routes.

n76 · January 1, 2026, 5:29pm

Contiguous even under the waters of Pyramid Lake?

Minh_Nguyen · January 1, 2026, 7:17pm

Haha, not another Route 112! I think the plan was only suggesting the historical designation for any portion that would get renumbered as an Interstate, not the entire length of Route 99. But it was an even vaguer line than the bit about Interstate numbering.

ZeLonewolf · January 1, 2026, 8:28pm

I think we should map a network=US:I:Future + ref=685 when we se signage like:

I’m not sure what a future interstate “corridor” is. It sounds like “the new highway will vaguely go in this general area”.

Minh_Nguyen · January 1, 2026, 9:59pm

I broadly agree with you but not for that reason.

The future Interstate corridor designation is based on the High Priority Corridor designation in ISTEA, as amended by SAFETEA-LU. This statute explicitly defines High Priority Corridors as specific segments of existing routes, which we’ve mapped. It calls them “corridors” only because the existing route can move from an older roadway onto a newer roadway, which is pretty much the point of this program.

Similarly, the Appalachian Development Highway System program designates lettered corridors that appear on some signs. Even though the word “corridor” legally refers to something wider than the existing roadway, the signs are intended to associate the corridor with the roadway.

This differs from how the Adventure Cycling Association has designated 50-mile-wide corridors for the development of U.S. Bicycle Route corridors. That’s so much wider than a standard bike trail that associating the corridor with a particular trail strays further into the realm of speculation. Even so, mappers have tended to put in state=proposed route relations that follow the most likely bike trail, in cases where the intention is very clear.

The future path of I-685 is designated as High Priority Corridor 92. NCDOT applied to AASHTO for the establishment of “Future I-685”, and AASHTO approved in 2022, contingent on FHWA approval. Under federal regulation, NCDOT was only allowed to post future Interstate corridor signs after securing FHWA approval.

The “Future 685” sign is nonstandard. It’s supposed to say “CORRIDOR” at the bottom. As of 2024, these signs aren’t supposed to feature the Interstate shield. Apparently omitting the word “INTERSTATE” wasn’t enough to avoid confusion with actual Interstates. Nevertheless, I think we can continue tagging future Interstate corridors as network=US:I:Future based on the plain text signs. Besides, transportation maps conventionally mark them with “FUTURE” above an Interstate shield.

The High Priority Corridor status in California is explicitly tied to a segment of Route 99, leaving no ambiguity:

The California Farm-to-Market Corridor, California State Route 99 from south of Bakersfield to Sacramento, California.

However, Caltrans has never applied to either AASHTO or FHWA for an Interstate 7 or 9 designation, so the future Interstate corridor is very clearly unnumbered and unsignposted. The only justification for a route relation is as a placeholder to prevent someone from mapping it as a numbered, signposted route other than Route 99.

Baloo_Uriza · January 2, 2026, 3:02pm

It usually means some DOT got a lot of money to “upgrade” a US highway to a freeway, whether it needed it or not. Long stretches of I 540 and US 71 were signed as Future I 49 before I 49 was completed through the Bella Vista gap at the Missouri/Arkansas border.

By the time the “Future” signs go up, the route’s nailed down.

Baloo_Uriza · January 2, 2026, 3:04pm

This isn’t the first time from the same user. Flap Slimy Outward also tried adding “I 42 FUT” (which, wrong, it’s not signed, and we don’t abbreviate refs even as we keep that deprecated tag for backwards compatibility), to a long section of US 412, despite lack of any I 42 Future signage, no political support for I 42, and gaining political support for removing the freeway I 42 is proposed to use in Tulsa.

ZeLonewolf · January 2, 2026, 3:32pm

IMO, signage on the ground should be a bare minimum requirement for mapping these future routes. And even then it might not be enough if the route isn’t clear.

Minh_Nguyen · January 2, 2026, 6:05pm

This has been a problem for years. Overly enthusiastic roadgeeks have attempted to add these supposedly future Interstates many times, sometimes as current Interstates (since reverted, now a real future Interstate by a different number).

We have coverage of 61 High Priority Corridors, including High Priority Corridor 54, the one concurrent with Route 99 in California. We’ve tolerated these route relations for 15 years because they’re tagged as a different kind of route, not future Interstates, and have unsigned_ref=* to indicate that the numbers only appear in the statute. If we were to delete them on verifiability grounds, I’m concerned we’d see even more overly optimistic Interstate mapping.

MxxCon · January 3, 2026, 4:43pm

In my opinion, even the existence of a “Future Interstate” sign would not be enough justification to add a new network= relation.

OSM is a database of the world now, not at some undetermined point in the future. I generally believe that proposed: and planned: and (I think in Canada I’ve seen financed:) similar prefixes don’t belong in OSM.

We should map it when it is actually there. Once the shovels hit the ground, we can map the construction features. If road signs are eventually added, we can map those specific signs, but we should only create a network= relation when the route is actually usable as part of that network. What useful purpose is served by mapping an interstate network that doesn’t effectively exist yet?

Minh_Nguyen · January 3, 2026, 5:32pm

Ohhh, lots of highway routes aren’t particularly useful. Maybe we don’t want to go there.

I agree that hearing “Future I-685” in turn-by-turn instructions would be silly, maybe sillier than hearing one of those unwieldy memorial name designations. But that’s something a router can easily avoid. For one thing, we already omit future Interstates from the way refs that routers unfortunately still use. What’s more, any router that does know how to consume route relations can easily make an editorial decision to ignore any network=US:*:Future route relation.

Meanwhile, road maps intended for the general public conventionally do show future Interstates and even select proposed highways. It’s of questionable benefit, but it’s up to the publisher how they want to fill any extra whitespace. For example, here’s LaDOTD bragging about a stretch of U.S. Route 90 that’s scheduled to become I-49 on one of the maps they hand out for free at the front desk of the I-10 welcome center. That’ll require the section of highway between Calumet and Morgan City to be upgraded to a freeway. Construction hasn’t begun as of writing.

Even once that stretch is complete, other stretches closer to New Orleans need to be upgraded before the I-49 designation can be extended south of Lafayette. Who knows when they’ll find the money for it. But it’s there on maps, which is certainly more than can be said for “Interstate 7 or 9”.

MxxCon · January 3, 2026, 5:48pm

Those are paper maps, which always have financial cost to keep up to date so they want them to be potentially useful for some time in the future. It’s not the same as digital maps which can be instantly updated, so I wouldn’t say it’s analogous example.