Partly — and the part contractors miss is that a towed drill rig is two things at once. Commercial auto generally covers the vehicle and its operation in transit, including the trailer if it is scheduled, but the mounted drill, boom, and gear may fall to contractors equipment instead. Whether the towed unit is even on your auto policy depends on your form, so the honest answer is that one rig usually splits across two policies.
This catches crews off guard because a drill rig or a bucket truck feels like a single thing — you tow it, you drive it, it is yours. To an insurer it is a vehicle and a machine bundled together, and those two halves are insured under different lines. Commercial auto is built around the chassis and the road; contractors equipment is built around the gear. Get the seam between them wrong and you can end up with a totaled drill and an auto policy that pays for the truck but not the thing that mattered. Knowing where the line falls is the difference between a rig that is covered end to end and one that is half-covered.
One rig, two coverage lines
When you tow a drill rig down the highway, you are moving two distinct insured interests at the same time. The first is the vehicle: the truck, the trailer, the chassis the rig rides on, and the liability and physical damage tied to driving or towing them. The second is the equipment: the directional drill, the boom, the splicers and locators — the high-value machinery that is the entire reason the rig exists. Those two halves look like one piece of iron going down the road, but commercial auto is written for the first and contractors equipment, an inland marine line, is written for the second.
That split is not a flaw in how the policies are designed; it is how mobile-equipment coverage has always worked. Auto answers for the vehicle and its operation. Inland marine answers for the gear that moves with it. A bucket truck is genuinely both — a roadworthy vehicle and a mounted boom — which is exactly why two policies can respond to one accident, and why the two have to be built to meet.
What commercial auto responds to in transit
The half that looks most like a normal auto claim is the vehicle and its operation on the road. If you are towing a drill rig and the trip ends in a collision, commercial auto is generally the line that responds to the truck, the liability if the accident injures someone or damages other property, and the physical damage to the vehicle itself — subject to your limits and your form. That is true whether the rig is being driven under its own power or towed behind a truck.
The detail that surprises contractors is the trailer. A towed trailer is not automatically covered just because it is hitched to an insured truck — coverage for trailer liability and physical damage can turn on whether the trailer is scheduled on the policy, how large it is, and which endorsements are in place. A trailer assumed onto the policy but never actually listed is one of the more common gaps we see on an auto file. So the first question on a towed rig is not only “does auto respond” but “is this specific trailer on the schedule,” and that is something to confirm rather than assume.
Where auto stops: the mounted gear falls to inland marine
Here is where the seam matters most. Commercial auto covers the vehicle and the trailer; it does not cover the specialized equipment mounted on or carried by them. The directional drill itself, the boom on a bucket truck, the fusion splicers in a van, the locators and reels — that gear is insured under contractors equipment, the inland marine line built for mobile equipment that travels between job sites and states. To an insurer, the chassis and the machine are different property, and they sit on different policies.
We do not re-derive the full inland marine mechanics here — the contractors equipment page walks how the form treats gear in transit, at the yard, and at an unattended site. The point for this question is narrow: when a towed rig is involved in a loss, the drill is most likely an equipment claim, not an auto claim. And because forms differ on how they handle permanently mounted equipment versus loose carried gear, whether a particular boom or drill is reached by auto or by inland marine depends on how it is scheduled — which is exactly why the two schedules cannot be bought in isolation.
Real-World Scenario: A crew tows a directional drill rig on a trailer to an out-of-state build, and the trailer fishtails and rolls on the highway. The truck is damaged, the trailer is bent, and a passing vehicle is struck in the incident — the kind of vehicle and third-party loss commercial auto is built to address. But the directional drill on the trailer is destroyed, and that is the machine that makes the crew money. The auto policy answers for the truck and the trailer; the drill is a contractors equipment claim. The crew that placed both lines together is covered end to end; the crew that assumed auto would catch the drill finds the seam mid-claim.
Why the two schedules have to be built together
A towed drill rig is the clearest reason commercial auto and contractors equipment are placed as a pair rather than as separate purchases. The two are not redundant and they are not interchangeable — they cover different halves of the same rig. The fix is not complicated, but it has to be deliberate: every vehicle, every trailer, and every mounted machine has to land clearly on either the auto schedule or the equipment schedule, with nothing assumed onto a policy that does not list it. That is the coordination that matters most for a directional drilling insurance operation running heavy rigs and for an overhead fiber installation insurance crew on bucket trucks, and it is closely related to the ownership question we take up in do I need commercial auto if my fiber crew owns its trucks. The same buried-utility exposure that makes a bore-strike a two-policy event in does general liability cover a directional drill hitting a gas line is why the rig that does the boring needs both its vehicle and its equipment covered without daylight between them. It is also one of the reasons the work is priced the way it is, which we break down in our fiber optic contractor insurance cost guide.
Check the schedule before a rollover tests the seam
Because the answer turns on what is scheduled and how your form treats towed and mounted units, “is my towed rig covered” is a question to settle before the haul, not after a rollover. A review confirms the trailer is actually listed on the auto policy, reads how the form handles permanently mounted equipment versus carried gear, and makes sure the contractors equipment schedule picks up the drill and boom the auto policy leaves out. Where heavier rigs run interstate, the review also flags whether the fleet trips federal motor-carrier considerations under the Federal Motor Carrier Safety Administration framework, and the limit structure is read against what your prime contracts demand — where a contract requires more than your primary auto layer, that is what an umbrella reaches over. Sound towing practice and load securement under OSHA and PHMSA safety standards, along with the towing and trailer-safety guidance from the National Highway Traffic Safety Administration, will not rewrite your policy language, but they reduce how often you test it.
The reliable path is to assume a towed rig will produce both kinds of loss and to carry both lines built to meet. Confirm what your auto policy does with the trailer, place a contractors equipment schedule sized to your gear, and have the two reviewed together so there is no daylight between them. When you are ready, start a quote and tell us what you tow and where, or browse the full coverage overview to see how the lines fit together. A towed drill rig is one of the few losses on a fiber job that can split across two policies — and it is entirely avoidable with both schedules built as one.