site-diary
Site Diary: Mountain Pass Bridge Construction
Saida Bilqiis Bajeh, GMNSE
11/20/2023
6 min read
# Site Diary: Mountain Pass Bridge Construction
## Week 1: Mobilization and Reality Check
Arriving at the Mountain Pass site in early April, the reality of this project hit immediately. Snow still covered the ground at 3,500 feet elevation, and our weather forecast showed only a 6-month construction window.
### Initial Challenges
- **Access**: Temporary construction road required 2 weeks to build
- **Weather**: Daily temperature swings of 40°F
- **Logistics**: 90-minute drive from nearest material supplier
## Month 2-3: Foundation Work
Foundation construction revealed unexpected conditions. At 25 feet depth on the west abutment, we encountered fractured bedrock requiring design modifications.
### Engineering Response
Our team quickly adapted:
- Increased foundation depth by 8 feet
- Added rock anchors for additional stability
- Modified drainage system for groundwater management
```
Original Design: 4 drilled shafts @ 30' depth
Revised Design: 6 drilled shafts @ 38' depth with rock anchors
Cost Impact: +$120K
Schedule Impact: +2 weeks (recovered later)
```
## Month 4-5: Steel Erection
Pre-fabricated steel components arrived on schedule, but weather didn't cooperate. We had planned for 4 weeks of steel erection work.
### Weather Delays
- Week 1: High winds (>40 mph) - no crane operations
- Week 2: Successful erection of 3 main girders
- Week 3: Rain and fog - reduced productivity
- Week 4: Completed primary structure
The decision to pre-fabricate proved critical. Traditional stick-built construction would have required 8-10 weeks in these conditions.
## Month 6: Deck Construction
Concrete deck placement required precise timing and preparation:
### Pre-Pour Preparations
1. **Weather Monitoring**: 7-day forecast review
2. **Material Staging**: Concrete trucks pre-positioned
3. **Curing Strategy**: Thermal blankets ready for overnight protection
4. **Backup Plans**: Alternative pour dates scheduled
The deck pour occurred over 3 days in late August:
- **Day 1**: West approach (120 cubic yards)
- **Day 2**: Main span (280 cubic yards) - critical pour
- **Day 3**: East approach (100 cubic yards)
## Lessons Learned
### What Worked
- **Pre-fabrication**: Reduced on-site work by 40%
- **Weather Contingency**: 3-week buffer proved necessary
- **Team Communication**: Daily briefings kept everyone aligned
- **Local Partnerships**: Nearby contractor provided emergency equipment access
### What We'd Change
- **Earlier Start**: Beginning in March (despite snow) would have provided more buffer
- **Larger Crew**: Adding 2 more workers would have recovered weather delays faster
- **Equipment Redundancy**: Backup crane on site would have prevented 3-day delay
## Final Thoughts
Mountain Pass Bridge tested our team's resilience and adaptability. The project finished on time and under budget, but more importantly, we built a structure that will serve the community for 100+ years.
*Interested in infrastructure projects in challenging environments? Check out our [Projects](/projects) portfolio.*
## Week 1: Mobilization and Reality Check
Arriving at the Mountain Pass site in early April, the reality of this project hit immediately. Snow still covered the ground at 3,500 feet elevation, and our weather forecast showed only a 6-month construction window.
### Initial Challenges
- **Access**: Temporary construction road required 2 weeks to build
- **Weather**: Daily temperature swings of 40°F
- **Logistics**: 90-minute drive from nearest material supplier
## Month 2-3: Foundation Work
Foundation construction revealed unexpected conditions. At 25 feet depth on the west abutment, we encountered fractured bedrock requiring design modifications.
### Engineering Response
Our team quickly adapted:
- Increased foundation depth by 8 feet
- Added rock anchors for additional stability
- Modified drainage system for groundwater management
```
Original Design: 4 drilled shafts @ 30' depth
Revised Design: 6 drilled shafts @ 38' depth with rock anchors
Cost Impact: +$120K
Schedule Impact: +2 weeks (recovered later)
```
## Month 4-5: Steel Erection
Pre-fabricated steel components arrived on schedule, but weather didn't cooperate. We had planned for 4 weeks of steel erection work.
### Weather Delays
- Week 1: High winds (>40 mph) - no crane operations
- Week 2: Successful erection of 3 main girders
- Week 3: Rain and fog - reduced productivity
- Week 4: Completed primary structure
The decision to pre-fabricate proved critical. Traditional stick-built construction would have required 8-10 weeks in these conditions.
## Month 6: Deck Construction
Concrete deck placement required precise timing and preparation:
### Pre-Pour Preparations
1. **Weather Monitoring**: 7-day forecast review
2. **Material Staging**: Concrete trucks pre-positioned
3. **Curing Strategy**: Thermal blankets ready for overnight protection
4. **Backup Plans**: Alternative pour dates scheduled
The deck pour occurred over 3 days in late August:
- **Day 1**: West approach (120 cubic yards)
- **Day 2**: Main span (280 cubic yards) - critical pour
- **Day 3**: East approach (100 cubic yards)
## Lessons Learned
### What Worked
- **Pre-fabrication**: Reduced on-site work by 40%
- **Weather Contingency**: 3-week buffer proved necessary
- **Team Communication**: Daily briefings kept everyone aligned
- **Local Partnerships**: Nearby contractor provided emergency equipment access
### What We'd Change
- **Earlier Start**: Beginning in March (despite snow) would have provided more buffer
- **Larger Crew**: Adding 2 more workers would have recovered weather delays faster
- **Equipment Redundancy**: Backup crane on site would have prevented 3-day delay
## Final Thoughts
Mountain Pass Bridge tested our team's resilience and adaptability. The project finished on time and under budget, but more importantly, we built a structure that will serve the community for 100+ years.
*Interested in infrastructure projects in challenging environments? Check out our [Projects](/projects) portfolio.*