Description:
Poles supporting overhead utilities in the right-of-way represent a significant safety hazard for drivers and occupants of vehicles. While other hazards exist on the roadside, vehicles that crash into these utility poles typically suffer serious damage and increase the risk of serious injury or death for the occupants. Over 1,000 fatalities each year are attributed to crashes involving utility poles.[1] Relocating overhead utilities in the right-of-way below the ground surface eliminates this safety hazard, improves the aesthetics of the roadway and adjoining properties, and can increase the reliability of the utilities. However, the cost of relocating existing overhead utilities to the subsurface often prohibits any large scale adoption of the practice. Innovative technological advances may afford the opportunity to significantly reduce this highway safety hazard.
The most significant issue in underground relocation of utilities beyond the cost is avoiding existing subsurface utilities and other obstructions. Particularly in corridors with a cluttered subsurface such as in urban environments, the precise location of existing utilities is often unknown. Even in cases where as-built drawings or other documentation exists, the accuracy and precision may not be good enough to reliably place additional utilities and avoid conflict with existing ones.
Rapidly developing technologies to reliably sense existing underground conditions and the location of existing underground utilities integrated with increasingly affordable robotic technologies may offer a promising and cost-effective solution to the dilemma of relocating overhead utilities. Nondestructive inspection techniques such as ground penetrating radar and thermography can be combined with more traditional location approaches such as magnetic field detection to more accurately locate existing utilities. In cases where trenches are open, advanced 3-dimensional data capture with LiDAR or photogrammetric techniques also provides accurate location information that can be combined into a common 3-dimensional digital model of the subsurface. Significant progress on the detection, location, and mapping of existing underground utilities has been made under the 2ndStrategic Highway Research Program (SHRP2) and research conducted by FHWA and the highway construction industry. These models will provide the necessary information on existing conditions to support accurate placement of overhead utilities into the subsurface.
To minimize cost and disruption, trenchless methods for utility relocation will be required. Horizontal directional boring technology is relatively mature for applications that do not require very accurate 3-dimensional positioning of the drill head. Advances in guided directional drilling and microtunneling techniques promise significant improvements in accuracy that may be sufficient and provide the necessary accuracy and control to place utilities in a complex subsurface environment that is characterized by a sufficiently accurate 3-dimensional model.
The desired outcome of the proposed research is a system that can robotically relocate existing overhead utilities to the subsurface in highway and road rights-of-way. The system should be accurate and precise enough to place utilities in complex subsurface environments such as those found in urban corridors. The robotic installation system will depend on an accurate 3-dimensional model of the subsurface that is derived from state-of-the-art remote sensing technology combined with existing information about buried utilities.
Expected Phase I Outcomes:
Phase I will explore and identify existing technologies that are capable of, or can be adapted to, the robotic installation of underground utilities. Similarly, Phase I will also examine current and emerging subsurface utility sensing and mapping technology to identify the most applicable technique(s) to exploit for use with a future automated subsurface utility relocation system. Lastly, this phase will determine the feasibility of integrating the identified subsurface sensing/mapping methods with the robotic technology to form a complete, automated subsurface utility relocation system.
Expected Phase II Outcomes:
Building on the information developed in Phase I, Phase II will produce a prototype system that can be demonstrated in a realistic environment by robotically installing utility cables in the subsurface where utilities and other obstructions already exist.
[1]National Cooperative Highway Research Program (NCHRP) Report 500 -- Guidance for Implementation of the AASHTO Strategic Highway Safety Plan; Volume 8: A Guide for Reducing Collisions Involving Utility Poles (2004).
