On Friday night, the rebuilt bore of the highway tunnel was still a work zone. By Monday morning, traffic was running through it under new lights, past a new lining and new fire systems, and the crews who rebuilt it had closed the second bore to start again. One weekend. That was the window the public felt, and it was the moment the whole first half of this design-build job had been planned around.
Why one bore at a time
The fastest way to rehabilitate a twin-bore tunnel is to close it. It is also the most expensive way for everyone who uses it. A full closure would push thousands of drivers a day onto local streets for months. So the plan kept one bore open in both directions while the other was rebuilt, with traffic shifted through crossovers at each portal.
That choice made the work harder and the site smaller. Our crews removed the old finishes, repaired and lined the bore, installed new lighting, jet fans and fire protection, and pulled the cable that ties it all to a new control system, all inside a work zone a few feet from live traffic in the other bore.
A weekend rehearsed for months
A traffic switch looks simple from the driver's seat. Behind it is a long list of things that all have to be finished at the same hour.
- Systems proven first. Lighting, ventilation, fire detection, cameras and emergency phones in the rebuilt bore were tested end to end, from the device in the tunnel to the screen in the control room, before the switch was scheduled.
- Striping, signs and barriers. Crossover barriers, signs and striping were staged and ready, so crews could place them in hours rather than days.
- A minute-by-minute plan. Every crew had its own timeline for the weekend, walked through in a full rehearsal the week before.
- Fallback triggers. The plan named the go and no-go decision points in advance, and who would make each call, so nobody had to improvise at 3 a.m.
- Constant communication. Closure notices and detour maps went out well ahead, coordinated with local agencies and emergency services.
The public saw one closed weekend. We saw a year of work arranged so that weekend was the only thing they would notice.
Project manager, Tum Harry
What comes next
With traffic in the rebuilt bore, the second bore gets the same treatment, faster this time, because the crews, the sequence and the lessons from the first one carry straight over. After that come the final system integration, punch list items and the documentation and training the owner needs to run the tunnel for the long run. Our thanks go to the crews, trade partners and traffic control teams who rebuilt one bore beside a live one, and to the drivers who gave us one weekend to make the switch.
