Fiber Optic Installation Under I-25: HDD Crosses 4-Lane Highway Without a Single Lane Closure

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A Colorado telecommunications provider needed fiber optic conduit installed beneath Interstate 25 near Fort Collins. Traditional open-cut trenching would have required weeks of lane closures, costly CDOT permits, and significant traffic disruption. Massive Services LLC used horizontal directional drilling to complete the 800-foot crossing in just 2 days with zero lane closures and zero traffic impact.

The Challenge

In late 2025, a regional telecommunications provider in northern Colorado was expanding its fiber optic network to serve growing residential and commercial demand along the Front Range corridor. A critical segment of the build-out required routing fiber optic cable beneath Interstate 25 between Fort Collins and Loveland, one of the busiest stretches of highway in the state with average daily traffic counts exceeding 70,000 vehicles.

Traditional open-cut trenching was the provider's initial consideration, but the logistics made it impractical. An open-trench crossing of I-25 would have required full lane closures on a 4-lane divided highway, extensive traffic control plans, and coordination with the Colorado Department of Transportation (CDOT). Estimated permitting timelines alone stretched 6 to 8 weeks, and the construction window for lane closures would have added another 2 to 3 weeks of active disruption. The total cost of traffic management, flagging crews, and potential CDOT fines for schedule overruns made the open-cut approach both expensive and risky.

The provider contacted Massive Services LLC to evaluate a trenchless alternative: horizontal directional drilling (HDD).

Planning & Permits

Before any equipment arrived on-site, our project team completed a thorough pre-construction planning phase over a 3-week period. The planning process included the following key steps:

• Subsurface utility engineering (SUE): We contracted a Level A SUE investigation to identify and map all existing utilities within the bore path, including a 12-inch water main, two natural gas lines, and an existing telecommunications conduit running parallel to the highway right-of-way.
• Geotechnical analysis: Soil borings were taken at both the entry and exit pit locations. The subsurface consisted primarily of compacted clay and sandy loam with a gravel layer at approximately 22 feet, consistent with the alluvial geology of the Cache la Poudre River floodplain.
• CDOT coordination: Because the HDD bore would pass beneath CDOT right-of-way without disturbing the road surface, the permitting process was streamlined to a utility accommodation permit rather than a full lane closure permit. This reduced the approval timeline from 6-8 weeks to 12 days.
• Bore path design: Our HDD engineers designed an 800-foot bore path at a depth of 30 feet beneath the highway surface, providing a minimum of 10 feet of clearance below the deepest identified utility and 6 feet of clearance below the highway's structural subbase. Entry angle was set at 12 degrees and exit angle at 10 degrees.
• 811 locate coordination: Colorado 811 utility locates were completed 5 business days prior to the scheduled drill date, with all utility owners confirming clearance for the proposed bore path.

The HDD Process

Day 1: Pilot Bore

Our crew mobilized to the site at 6:00 AM with a Vermeer D40x55 S3 horizontal directional drill rig, a 500-gallon mixing system for drilling fluid, and a full complement of tooling for the soil conditions. The 5-person crew set up on the east side of I-25 on a pre-graded staging pad within the telecommunications provider's easement.

The pilot bore began at 7:30 AM. The drill head, equipped with a DigiTrak F5 walkover locating system, was steered along the pre-engineered bore path. Bentonite-based drilling fluid was continuously pumped at a rate of 30 gallons per minute to stabilize the bore hole, cool the drill head, and carry cuttings back to the entry pit for reclamation.

A dedicated locator technician tracked the drill head's position, depth, and pitch in real time from the highway median and shoulder, requiring only brief pedestrian access to the right-of-way shoulder — no lane closures needed. The pilot bore reached the exit pit on the west side of I-25 at 4:15 PM, confirming accurate alignment within 2 inches of the designed exit point.

Day 2: Reaming and Pullback

On the second day, the crew performed a single-pass ream of the pilot bore using a 12-inch fly cutter to enlarge the bore hole to its final diameter. The reaming pass was completed by 10:30 AM. Following the ream, the crew attached a 4-inch HDPE conduit to a swivel and barrel reamer and began the pullback operation.

The 800-foot section of 4-inch SDR 11 HDPE conduit was pulled back through the bore in a single continuous operation, completed by 1:45 PM. Pullback tension was monitored throughout and remained well within the conduit's safe pull strength rating. A final walkover locate confirmed the conduit's as-built position matched the design profile. The crew demobilized the drill rig and restored both entry and exit areas by 4:00 PM.

The Results

The fiber optic highway crossing was completed on schedule and within budget, delivering measurable advantages over the traditional open-cut alternative:

• Zero lane closures: Not a single lane of I-25 was closed during the entire operation. Over 70,000 daily commuters experienced no disruption.
• 2-day completion: The on-site work was finished in 2 working days, compared to an estimated 2-3 weeks for open-cut construction.
• Permit timeline reduced by 80%: The HDD approach required only a utility accommodation permit (12 days) versus a full lane closure permit (6-8 weeks).
• Cost savings of approximately 40%: By eliminating traffic control crews, lane closure equipment, extended construction schedules, and potential CDOT penalty fees, the total project cost was approximately 40% less than the open-cut estimate.
• Minimal surface disturbance: The only ground disturbance occurred at the entry and exit pits, each approximately 6 feet by 10 feet, both located on private easement land off the highway right-of-way.
• 800 feet of 4-inch HDPE conduit installed: The conduit is rated for multiple fiber optic cable pulls, giving the telecommunications provider future capacity without additional boring.
• Zero safety incidents: The project was completed with no injuries, no near-misses, and full compliance with OSHA and CDOT safety requirements.

Why HDD for Highway Crossings

Horizontal directional drilling is the preferred method for installing underground utilities beneath highways, railroads, rivers, and other sensitive surface features. For highway crossings specifically, HDD offers distinct advantages that make it the standard approach for telecommunications, gas, water, and electrical installations:

No traffic disruption. HDD operations take place entirely at entry and exit points that are typically 50 to 200 feet away from the road surface. The bore passes 20 to 40 feet beneath the highway, well below the structural layers of the roadway. Drivers and commuters are unaffected.

Faster project timelines. A typical HDD highway crossing takes 1 to 3 days of on-site work, compared to 1 to 4 weeks for open-cut methods. The permitting process is also significantly shorter because lane closure permits, traffic management plans, and CDOT construction windows are not required.

Lower total project cost. While the per-foot cost of HDD boring may be higher than open-cut trenching, the elimination of traffic control, extended crew time, road restoration, and permit fees makes HDD more cost-effective for crossings over 200 feet.

Reduced environmental impact. HDD minimizes surface disturbance, preserves existing landscaping and vegetation, and avoids the large spoil piles and road base disposal associated with open-cut methods. Drilling fluid is contained and recycled on-site.

Preservation of road integrity. Open-cut trenching through a highway requires cutting and restoring the road surface, which often results in settlement, cracking, and reduced pavement life. HDD leaves the road structure completely intact.

Massive Services LLC operates HDD equipment capable of bores up to 1,500 feet in length and conduit diameters up to 12 inches. Our crews are experienced in highway, railroad, and river crossings throughout Colorado and North Dakota, and we maintain all required CDOT and state DOT certifications for work within highway rights-of-way.