The Ancillary Structures Program is committed to performing comprehensive transportation asset management of ancillary structures. The program will provide asset condition data regarding inventory, inspection, and maintenance priorities to maintain safe and efficient public roadway operations in the state of Michigan.
To minimize public safety risks due to deterioration of asset conditions
To develop an asset management program for ancillary structures
To develop and maintain an ancillary structures database framework
To develop and maintain an ancillary structures program which results in consistency in managing the various ancillary structure types deployed by MDOT
Asset management is a systematic process of maintaining, upgrading, and operating physical assets cost-effectively. Asset management focuses on developing a comprehensive management system that captures the entire life cycle of assets and identifies what the assets are, their location, and the infrastructure condition. Asset infrastructure conditions are also tracked so future renewal and replacement decisions can be determined.
Accurate, reliable, and current data forms the foundation of any asset management system. A robust database to capture asset attributes and record conditions is essential and helps effectively manage future infrastructure investments to avoid costly fixes.
The Michigan Department of Transportation (MDOT) established the Ancillary Structures Program to develop an asset management system in Michigan and maintain a comprehensive statewide inventory of MDOT-owned ancillary structure assets.
The program’s goal is to minimize public safety risks that may be due to the deterioration of assets. Michigan is one of a handful of states to integrate ancillary structure asset types in the management of planning and design processes statewide.
Ancillary structures play a critical role in roadway network operations and safety. The structures serve a secondary purpose to the roads and bridges within the transportation system providing necessary support. There are 16 total ancillary structure types included within the MDOT Ancillary Structures Program. Click here to be directed to a list of the ancillary structure types and their definitions.
Many ancillary structures are directly overhead, adjacent to, or below the roadway users, and critical to the safety of the traveling public. Failure of an ancillary structure could have immediate, severe, and catastrophic impacts on public safety. Establishing a system of asset management is essential in ensuring public safety and welfare.
MDOT’s Ancillary Structures Program was established in late 2020 and inspections began for assets in 2021, including culverts less than 10-foot span, retaining walls, cantilever and truss sign support structures.
Stakeholder and risk meetings were held at the beginning of the program to engage with regions and integrate feedback. The Michigan Ancillary Structures Inspection Manual (MiASIM) was published in 2022, providing information on inspection requirements and assessment of ancillary structures conditions. Updates to the MiASIM are ongoing as new information and standards are received.
In spring of 2023, inspections for the remaining asset types began for spun concrete poles, steel strain poles, noise walls, mast arms, dynamic message signs, and frangible and non-frangible pole structures. Inspections for embedded steel poles, embedded wood poles, high mast lighting towers, communication towers, and environmental sensor stations began in summer 2023.
Through the Go-Forward plan for the program, MDOT divided the 16 asset types among three different risk-based levels starting with assets that, if failure occurs, would have the greatest impact to safety, mobility, and commerce due to unplanned roadway closures. The first assets to start inspection were culverts, retaining walls, cantilever sign support structures, and truss sign support structures in 2021.
Through the establishment of the program, Michigan has developed a programmatic system for future asset renewal and replacement. Information on critical asset conditions, inspection progress, Requests for Action (RFA), Work Recommendation (Work Rec) status, and planned inspections are all available in real-time online.
This program incorporates all areas of MDOT – planning, design, construction, maintenance, and operations – in a holistic approach to efficiently preserve the roadway system and optimize the investment of limited public funds. Each area uses the information provided by the program to continuously improve both initial and long-term quality of the assets placed into service.
Both Michigan residents and the traveling public benefit from an asset management program. Program outcomes also have a direct economic benefit to the local, regional, and national economy.
Locally, the need to mobilize a dedicated inspection team has created workforce development opportunities with on-the-job training provided by the program, creating new career pathways to attract talent to the transportation industry. On a regional and national level, the proactive identification of issues to ancillary structures statewide and corrective actions to maintain infrastructure in a state of good repair have limited emergency closures that may impact system users or cause freight shipment delays.
The successful development and rollout of the MDOT’s Ancillary Structures Program also serves as a model for other transportation agencies to follow with its comprehensive approach that includes all asset types.
In fiscal year 2020, the Ancillary Structures Program received funding from the Department of Transportation state budget to manage all ancillary structure assets statewide, accumulating to a growing number of more than 50,000 assets. This was a long-term program set out to access and manage assets through MDOT’s Bridges and Structures sector under Structure Preservation. The Bureau of Bridges and Structures “Proposal for Change” authorized funding approval for asset inventory and inspection with $10 million per year. This was based on estimated annual field inspection costs and management of the data files to support the program.
MDOT's Ancillary Structures Program partners serve an integral role in maintaining a state of good repair for all of Michigan’s ancillary structure assets. MDOT hired HNTB as a Program Management Consultant (PMC) to help staff the program and provide inspection, engineering, and technology resources as an extension of MDOT staff; the PMC team includes other private sector partners located across Michigan.
Within MDOT, the team has built a network of MDOT staff who serve as Region Champions and Deputy Region Champions to further integrate the program into day-to-day MDOT operations. These Region Champions provide feedback on tailoring various aspects of the program to meet each region’s needs and provide guidance on the use of region resources and region traffic and lane closure restrictions.
Click through below for a list of the ancillary structure asset types that are included within the Ancillary Structures Program, along with their definitions and images. Contact us if you have additional questions or comments.
A cantilever structure consists of a steel rigid structural element extending above the roadway and is supported at only one end with a concrete foundation. Cantilever structures are structural supports for static traffic signs.
Communication towers are freestanding structures designed to support antennas for telecommunications and broadcasting, supporting various signals, including television, cellular phone, wireless internet, and radio. They may gather sensor data and camera images, which are then distributed over cellular communications to servers hosted by MDOT. The towers consist of three main vertical supports called legs, each mounted on a separate concrete foundation with anchor bolts. The vertical supports have an interconnected lattice framework with diagonal bracing at lower elevations, which merge into a single vertical lattice structure at higher elevations. Michigan is the first state to use Unmanned Aerial Vehicles (UAV), commonly known as drones, to inspect communication towers.
A culvert is a structure that moves surface water through a roadway embankment and/or away from the highway and ensures that roadways properly drain to prevent flooding. The culverts part of the MDOT program have a combined span of less than 10 feet measured along the centerline of the roadway. A culvert is typically covered with soil and must also support highway traffic above. Culverts are differentiated from storm sewers in that they are straight-line conduits open at each end and typically do not include intermediate drainage structures (manholes, catch basins etc.)
Dynamic message signs support structures consist of a standalone vertical support with horizontal arms which support electronic signs and access walkways. They are mounted on a concrete foundation with anchor bolts and often hold programmable electronic signs that are located along highways and roads to provide real-time information to drivers.
Embedded steel and wood poles are used to support span wires, signs, signals, lighting, cameras, or other traffic appurtenances, and generally located on non-freeway routes and installed at intersections. They may be constructed of round or multi-sided steel cross-sections, or timber and may have anchor wires to stabilize the pole with a tensioned cable. The poles are directly embedded in soil or cast in place in concrete, unlike steel strain poles that have a concrete foundation to support the pole structure.
ESS towers are designed to gather sensor data and camera images, which are then distributed over cellular communication to servers hosted by MDOT. To function, most towers contain a power supply cabinet and sensors capable of acting as atmospheric sensors, precipitation sensors, and/or weather stations. ESS Towers are sometimes referred as a Road Weather Information System (RWIS). The structure is standalone and built using steel and/or aluminum and supported on a concrete foundation with anchor bolts used to support a variety of sensory attachments.
The frangible pole structures have a transformer base designed to break away at impact to protect the safety of motorists. They are primarily used in areas with higher risks of collisions and within the roadway clear zones, pedestrian walkways, or in close proximity to traffic. The structure is either a steel or aluminum pole mounted onto a cast aluminum transformer base, which is mounted to the concrete foundation. The frangible poles may support a variety of luminaires and different types of pole attachments and connections.
HMLTs are tall, vertical light poles mounted on a concrete foundation with anchor bolts, with heights ranging from 60-200 feet. HMLTs are designed to support powerful lighting fixtures at a considerable height above ground delivering adequate and uniform illumination over a vast area and along roadways. The poles may be constructed of galvanized or weathering steel and may be round or multi-sided and assembled from multiple pieces joined together with slip joints to help with protection against rust and corrosion. The lighting fixtures are mounted with a lowering device contained within the pole to allow for the array of lights to be lowered for maintenance. Michigan is the first state to use Unmanned Aerial Vehicles (UAV), commonly known as drones, to inspect high mast towers.
Mast Arms are steel pole structures with one or more horizontal beams or arms that extend from the vertical support structure and are commonly used to hold traffic signals, luminaries, signs, cameras, and other appurtenances. The steel pole is supported on a drilled shaft concrete foundation with anchor bolts.
A noise barrier wall is constructed of steel, concrete, and other materials to alter the noise travel from vehicles along a highway corridor by absorbing or reflecting the noise. Damage to the wall may decrease its effectiveness in reducing traffic noise.
The non-frangible pole structures are not considered breakaway structures and are used outside of roadway clear zones or are shielded typically by a guardrail to protect motorists. The steel or aluminum pole is mounted directly on a concrete foundation with anchor bolts. The non-frangible poles may support a variety of luminaires and different types of pole attachments and connections.
An earth retaining structure, often located along a highway, that retains and stabilizes unstable soil mass by means of lateral support or reinforcement, with a height of 4 feet or greater and an angle of face inclination greater than 70 degrees from horizontal. Generally, one end of the retaining wall is attached to either soil, a bridge abutment, or other structure(s) and the other to soil.
Spun concrete poles are high mast tension reinforced poles used to support traffic technology such as cameras and radar detectors. Instead of standard concrete foundations with anchor bolts, these poles are installed in a drilled shaft foundation that is then filled with concrete. The first spun concrete poles installed were embedded in soil, similar to embedded poles.
A steel strain pole is a standalone vertical pole made of steel that supports signals, lighting, cameras, or other traffic devices with a span wire support system to hold the wires, cables, and other equipment. They are constructed in a variety of configurations and may be round or multi-sided and are supported on a drilled shaft concrete foundation. Steel strain poles, unlike embedded poles that are placed in soil, use anchor bolts to transfer load from the pole to the concrete foundation.
A truss structure consists of a steel rigid structural element spanning across the roadway with supporting columns at both ends with concrete foundations. Truss structures are structural supports for static traffic signs.
A component is a set of related elements that, when combined with other components, make up an asset. Component Ratings provide a means to determine the safety of the structure. The Component Rating scale ranges from 0-9 and each rating has a Condition State associated with it.
COMPONENT RATING | CONDITION | CONDITION STATE |
|---|---|---|
9 | NEW | Like new, within normal range for a newly installed structure |
8 | GOOD | Only minor distress or deterioration |
7 | GOOD | Some problems noted |
6 | SATISFACTORY | Some moderate or multiple indications of distress/deterioration |
5 | FAIR | Moderate or multiple indications of distress/deterioration affecting performance |
4 | POOR | Significant distress |
3 | SEVERE | Significant distress/deterioration with potential for local failure |
2 | CRITICAL | Advanced deterioration with potential for failure of primary structural elements |
1 | IMMINENT | Imminent failure which could threaten public safety |
0 | FAILED | Failure has occurred |
An element is an individual piece of a component that can be condition assessed on its engineering or maintenance behavior. Element ratings are less safety related and are data driven to allow MDOT to make decisions regarding maintenance and funding. The element inspection is quantity-based, and each quantity is assigned a Condition State to reflect the differing categories of deterioration that often exist on elements. Elements are rated on a four-tier scale ranging from Severe to Good.
GOOD | FAIR | POOR | SEVERE | NOT RATED | |
|---|---|---|---|---|---|
ACTION INDICATED | No action is recommended. Note in inspection report only. | No immediate action is recommended but more frequent inspection may be warranted. Maintenance personnel should be informed. | Inspector evaluates need for corrective action and makes recommendations in inspection report. | Corrective action is required and urgent. Engineering evaluation is required to specify appropriate repair. | No action is required (Except when review could not be performed due to conditions). |
CONDITION DESCRIPTION | Like new with little or no deterioration. Structurally sound and functionally adequate. | Minor to moderate deterioration. Structurally sound with adequate function. | Significant deterioration. May not have adequate function. Maintenance or repair required. | Major deterioration. Failure may have occurred. Requires maintenance, repair, or replacement. | The element was not part of the system design and is not required for functional adequacy. This includes items missing due to vandalism. Also includes inaccessible items that need to be reviewed. |
MDOT inspectors issue a Request for Action (RFA) when the ancillary structure asset has a structural or safety issue upon inspection and requires follow-up inspection or action to schedule for repair more urgently than other work. These situations are addressed using emergency or high-priority procedures and may require follow up documentation. RFAs are defined by varying degrees from Priority Level 1-3 of urgency requiring ongoing prioritization and monitoring implementation by the state. The levels of RFAs are defined as:
Priority Level 1 – Repairs, mitigation or monitoring is required as soon as reasonably possible for public safety and the presence of an onsite inspector is required until the issue is addressed.
Priority Level 2 – Repairs, mitigation or monitoring is to be completed generally within 1 year or as determined by a qualified engineer.
Priority Level 3 – Repairs, mitigation or monitoring as determined per engineering judgement. The deficiency is not seen to be a critical threat to public safety though could eventually be if left unaddressed over a long period of time.
Work recommendations are used for maintenance related issues that are not safety related and do not require immediate action. Work recommendations are made by inspectors to extend the service life of existing assets and are a part of the inspection process.
The Ancillary Structures Program spans and incorporates all areas of MDOT from planning, design, construction, maintenance, and operations, requiring the help of its partners and program management consultant in multiple areas of the program. The Ancillary Structures Program attracts new people to the transportation industry and increases diversity throughout the program.
The program’s required in-house inspection training program allows for people who are new to the industry to receive necessary safety and program-related knowledge, creating new career opportunities even for participants without a college degree.
"When I come across an issue with an asset, I feel proactive and productive. Our system and the app we use sets us up for success with proper communication, proper documentation of the issues, and proper response time by HNTB and MDOT."
"Having the opportunity to work on MDOT’s Ancillary Structures Program as an inspector is incredibly rewarding and professionally enriching. The program's focus on ancillary structures is essential for ensuring that these often-overlooked components function correctly and safely. Being involved in this program means that I play a crucial role in maintaining and improving the reliability of our transportation network."
"It means a lot to me to be able to work on MDOT's Ancillary Structures Program. I like the partnership we have with them so we can make sure all the people are safe in the areas and everything is caught and noticed."
member dedicated inspection team mobilized to date
new employee hires to the
Project Management Consulting (PMC) team since January 2023
new hires are new to the transportation industry
PMC TEAM MEMBERS | NUMBER OF INSPECTORS WORKING ON THE PROGRAM | NEW HIRES (SINCE JAN. 2023) | NEW TO THE INDUSTRY |
|---|---|---|---|
HNTB | 8 | 8 | 7 |
SME | 4 | 1 | 1 |
COLLINS | 2 | 0 | 0 |
RS&H | 5 | 3 | 1 |
TOTAL | 19 | 12 | 9 |
Safety drives the main ongoing mission of the program and the need for its establishment. MDOT is committed to ensuring the safety of its employees, partners, and the public through comprehensive measures that foster the prevention of incidents. MDOT occupational safety guidelines are instituted because of the regulations stated under Public Act 154 of 1974; the provisions of which are enforced by the Michigan Occupational Safety and Health Administration (MIOSHA).
MDOT ensures all ancillary structure inspectors working for the program receive proper training by requiring a 10-hour MIOSHA training and separate Work Zone Traffic safety training prior to working and deployment into fieldwork. During routine and onsite inspections, inspectors are required to wear full personal protective equipment and usually work in teams of two.
The Michigan Ancillary Structures Inspection Manual (MiASIM) details a program safety plan in Section 1.5.
