Under the I-5, the Peters Canyon Hiking and Riding Trail runs through a strip of concrete and dirt. Above it, crews are rebuilding the freeway bridge, and they will be there for a while. The Orange County Transportation Authority's construction alert dated Nov. 6 puts bridge foundation and abutment work at the trail crossing from the week of Nov. 9 through spring 2027. That runs well past the "late 2026" most Northpark neighbors heard about in August.
When the trail closes at the freeway, the suggested way around goes onto Culver Drive. In the same alert, OCTA lists Culver at I-5 as the next spot for long-term lane closures, tentatively starting the week of Nov. 30. Meanwhile, the median lanes on Jamboree at I-5 are set to reopen the week of Nov. 16. For the next few months, the freeway project's pressure on Northpark moves from its east edge to its west edge, onto the same street that serves as the trail detour.
What the alert actually schedules at the trail bridge
The bridge at the trail is one of several I-5 crossings being widened as part of OCTA's project between the I-405 and SR-55. OCTA lists each crossing separately, and the Peters Canyon entry has three parts:
| Work at the Peters Canyon Trail/I-5 bridge | Tentative timing per OCTA's Nov. 6 alert | What OCTA says about access |
|---|---|---|
| Bridge foundation and abutment work | Week of Nov. 9 through spring 2027 | Daytime work behind concrete barriers |
| Wall demolition with partial pedestrian and bike lane closure | Monday, Nov. 16 | "Access will be maintained." |
| Temporary support structures and girder installation | Mid-November through mid-January 2027 | Nighttime activity with full road closures, details to come |
The Nov. 16 partial closure was already moved once. OCTA's Oct. 30 alert had it on Nov. 9, and the Nov. 6 alert pushed it back a week. Every date in these alerts is labeled tentative for good reason.
OCTA lists work hours of as early as 6 a.m. to 4 p.m. for daytime and as early as 10 p.m. to 5 a.m. for nighttime. A dawn ride or an after-work walk can fall in different construction windows on different days.
Why "late 2026" and "spring 2027" are both right
In August, the City of Irvine's weekly traffic advisory said intermittent full closures of the Peters Canyon Hiking and Riding Trail at I-5 "may occur through late 2026," with daytime construction underway on the outer portions of the bridge. Councilmember Liu sent out a notice, which the Bicycle Club of Irvine passed along. It said work would start affecting the trail Aug. 31 and that the stretch between Bryan Avenue and Harvard Avenue/Walnut Avenue would be fully closed "during portions of construction."
These dates describe two different things. "Late 2026" is the window for possible intermittent full trail closures. "Spring 2027" is how long the bridge work itself is scheduled to last. OCTA's newest alert says access will be maintained during the Nov. 16 partial lane closure, lists the girder work as nighttime activity with full road closures still to be detailed, and keeps the bridge under construction into spring.
The work at the trail is part of a much longer project. On its I-5 project overview, OCTA lists two segments. I-405 to Yale is anticipated from Spring 2026 to mid-2029, and Yale to SR-55 from Spring 2026 to late 2029. Each segment adds one regular lane in each direction, plus auxiliary merge lanes and some ramp changes. The trail bridge has to get longer because the freeway is getting wider, and that is why this crossing will see crews for years, with on-and-off disruption.
Jamboree reopens as Culver narrows
On the east side of Northpark, OCTA's alert lists the long-term median lane closures on Jamboree at I-5 as reopening the week of Nov. 16. Jamboree's bridge is not done. Barrier wall work is planned from mid-December through January 2027, one nighttime full road closure is expected in January, and roadway reconstruction is scheduled from early 2027 through September 2027. Still, the lanes along the median are scheduled to come back.
On the west side, Culver at I-5 goes the other way. The alert lists long-term lane closures tentatively starting the week of Nov. 30. They affect the lanes closest to the median in both directions on Culver, for cast-in-drill-hole work, which means drilling and pouring foundation piles. The City first flagged this in August, when it said crews would put in concrete barriers and close the inside lanes on Culver at the I-5 bridge "for a long-term closure to be scheduled this fall."
OCTA has also scheduled nighttime dirt removal along northbound I-5 near the Culver Drive on-ramp from as early as Nov. 9 through late November, as part of its retaining wall and sound wall work.
Now look at the trail detour. According to the Bicycle Club of Irvine's write-up, OCTA's suggested route around the closed trail segment uses Walnut, Culver and Bryan. On any day the trail fully closes from now into winter, the official way around puts walkers and riders on a street where drivers will be squeezed into fewer lanes at the freeway.
The route local cyclists use instead
The Bicycle Club of Irvine has already worked out an answer, and it skips Culver. The club wrote that freeway work has made Culver "worse than usual" and that its routes never use Culver between Walnut and Bryan. Its route notes move the detour east to Tustin Ranch Road:
- Heading south toward Walnut: leave the path at Bryan, take Tustin Ranch, then Walnut, and rejoin the trail.
- Heading north toward Bryan: reverse it, Walnut to Tustin Ranch to Bryan, and back onto the path.
Bryan and Walnut are the two crossings that matter. Bryan is the last access point north of the freeway and Walnut is the first one south of it, so the Tustin Ranch loop connects them without touching the Culver interchange.
Where the trail goes on either side of the freeway
It's easy to forget how much depends on that one underpass. The OC Parks regional trails brochure describes the Peters Canyon Regional Trail as a multi-use trail running through Orange, Tustin and Irvine. It is also a segment of the Mountains-to-Sea route, which links Irvine Regional Park and Peters Canyon Regional Park with Newport Beach. Farther south, the San Diego Creek Trail connects Mason Regional Park with the Upper Newport Bay Nature Preserve. For Northpark, the crossing at I-5 is the way south to all of that.
North of the freeway, the network isn't affected. The Hicks Canyon Trail leaves the Peters Canyon Trail in Northpark Village and runs to Portola Parkway, according to a 2019 Irvine Standard feature on the trail. OC Parks lists Hicks Canyon Community Park as parking for the Hicks Regional Trail, which connects to the Peters Canyon Regional Trail. A loop that heads north into Hicks Canyon instead of south under the I-5 avoids the construction completely.
Checking before you head out
OCTA posts the up-to-date schedule in its weekly construction alerts and on its I-5 project page. For closures and detours, its alerts point to a Google interactive map and to the Waze app. The Nov. 6 alert says "check back for more details" next to the girder installation and the Culver closure. Those two items will shape Northpark's December.
For a trail user, the dates to watch are these:
- Monday, Nov. 16: wall demolition at the trail bridge, with a partial pedestrian and bike lane closure and access maintained.
- Week of Nov. 16: Jamboree's median lanes at I-5 scheduled to reopen.
- Mid-November through mid-January 2027: nighttime girder work at the trail bridge, with full road closures still to be announced.
- Week of Nov. 30: long-term inside-lane closures on Culver at I-5, tentatively.
- Spring 2027: bridge foundation and abutment work at the trail scheduled to wrap up.
A project that runs into 2029 shapes how people get around Northpark: which arterial is slow, which trail crossing is open, and how long the drive to the freeway takes. At Julie Tran, we keep up with changes like these because they come up whenever a neighbor asks what living near a particular street is like right now. If you're thinking about your home's value while this construction continues, request a complimentary consultation and home valuation. We'll walk through what the I-5 schedule means for your part of Northpark.