Earth 

Retaining 

Structures 

and Asset 

Management 
 

 

 

 

 

 

 

Earth Retaining Structures 

and Asset Management 

A Critical Component Tool in 

Maintaining Public Safety 

Earth Retaining Structures (ERS) are often 

an overlooked critical component of America’s 

surface transportation network. Each year, 

more than 160 million sq ft of permanent 

ERS are constructed in the United States. 

Current applications of ERS in highway 

projects accelerate construction, reduce costs, 

and enable the use of complex geometric 

designs. The use of ERS elements also enables 

vehicles to travel at increased speeds, reduces 

congestion, and lessens the environmental 

impact of highway and bridge construction. 

Ultimately, ERS serve as a vital tool in 

the successful movement of both people 

and goods across the country. 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

A Significant and Growing 

Asset Investment 

The current number of ERS used for transportation applications represents a significant asset 

investment. With the initial cost of building ERS 

often reaching or exceeding $100 per square foot 

of surface area, the total construction cost of the 

Nation’s ERS network is enormous. This network 

has expanded greatly during the past two decades 

due to increases in urban development, transportation capacity demands, and construction in 

complex and difficult terrain. The demand for 

ERS on America’s highways and bridges is only 

expected to increase in the future. Today, the construction of a single complex urban interchange 

routinely requires tens of thousands of square 

feet of ERS’s. The increased demand for ERS in 

transportation applications has been accompanied by the development of new materials and 

systems for design and construction. 

Permanent ERS, which may vary in height from 

4 ft to more than 100 ft, are built to withstand 

significant technical demands and to resist very 

large forces. They frequently must be constructed 

in challenging site conditions, including mountainous terrain, soft ground, and sites that are 

below water. Some modern ERS systems require 

that engineered materials such as plastics, concrete, and steel be buried in harsh underground 

environments of soil and rock that may adversely 

influence the long-term engineering properties 

of the materials. ERS often have assumed design 

lives of 100 years, but knowledge of actual design 

life for these structures is minimal and failures 

that have occurred to date have happened without warning. Repairing these failed structures is 

very expensive, complex, and difficult to implement. Repairs of even single, moderately sized 

ERS installations often cost millions of dollars. 
 

 

 

 

 

 

 

 

 

 

 

 

 

	 	 	 	 	 	 	

	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	

Loss of life due to failed ERS has been rare but safety remains a primary concern, as most ERS installations either 

directly support bridge components or roadways, or support ground and other transportation features that are 

immediately adjacent to a bridge or highway. While the 

transportation community’s knowledge of deterioration 

mechanics and methods to assess in-service performance 

has been limited to date, asset management (AM) offers 

important tools and techniques to help in evaluating ERS 

assets. 

An Essential Part of an Asset 

Management Program 

When developing long- and short-term programming and 

budgeting plans, it is critical that transportation agencies 

start with clearly identified inventories and condition assessments. AM plans must be data driven and must include 

performance measures that relate to policy objectives. 

Engineering and economic analysis and risk assessment 

are especially important when trade-off decisions are made 

on how to best address the transportation agency’s many 

needs, as well as in support of which projects will be funded 

based upon quality information and analysis. 

As States and other transportation infrastructure owners determine and prioritize their highway needs, they can 

use transportation asset management (TAM) techniques 

and data tools to collect and analyze data, measure system 

performance, identify strategies, set goals, develop effective 

performance measures, and support integrated decisions in 

programming projects. ERS should be included in a TAM program, along with pavements, bridges, ancillary structures, etc., 

to help ensure optimal usage of limited available funding. 

•	 How many earth retaining structures(ERS) does

your agency own? 

•	 How old are the structures?

•	 What istheir condition and what istheir remaining

service life? 

• What isthe likelihood that one will collapse or

experience excessive serviceability problems? 
	 	 	 	 	 	 	 	 	 	

 

 

 

 

	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

 

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

 

• What risk or impact would such a collapse present

to the traveling public or adjacent property? 

These are just some of the questions that can be answered 

if your agency uses TAM techniques and data tools to 

inventory and evaluate its ERS networks and to start incorporating ERS in its asset management plan. An ERS management system can provide valuable information on the 

inventory, condition, maintenance needs, and performance 

of this important infrastructure asset. 

Introducing an Asset Management System 

As transportation agencies begin to recognize the importance of this asset investment, a few agencies have developed ERS inventories that will allow them to begin systematic evaluations of their ERS network, develop improved 

design and construction details and inspection practices, 

develop strategies for maintenance and rehabilitation, and 

develop appropriate monitoring protocols to assess longterm behavior. The following are a few examples: 

•	 The Oregon Department of Transportation (ODOT) is

embarking on a retaining wall management program to 

inventory and assessthe asset acrossthe State. ODOT

estimates it has over 10,000 retaining walls statewide, 

with an estimated replacement cost of more than $300 

million. The agency is taking these measures because it 

has identified retaining walls as critical assets that could 

have significant consequences and risk if they fail. 

•	 The City of Cincinnati has been using a retaining wall

inventory and inspection system since 1990. The system allowsthe City to maintain a prioritized list of

repairs and replacements based on regular inspections; 

in addition, the system helpsthe City respond rapidly

to public concerns about its walls. The system currently 

tracks 6,796 retaining walls within the right-of-way, 

equivalent to approximately 159 miles in length, which 

includes privately owned walls that affect the right-ofway. Of the retaining walls within the right-of-way, the

City isresponsible for maintaining 1,827 of the walls,

equivalent to approximately 60 miles in length. The city 
	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	

 

	 	 	 	 	 	 	 	 	

	 	 	 	 	 	 	 	 	

 

 

	 	 	 	 	

 

	 	

	 	 	 	 	

	 	 	 	 	 	 	

	 	 	 	 	 	

	 	 	 	 	 	 	

 

engineer’s office finds this program to be a very useful 

tool for managing ERS assets. 

•	 The National Park Service (NPS) hasrecently begun

implementing an ERS asset management program. 

The NPS structures range in age from newly constructed to over 80 years old, with many showing signs of deterioration. These critical structures support park roads, 

as well asscenic vistas and overlooks. FHWA’s Federal

Lands Highway Division office is developing an inventory and condition assessment of all ERS associated with 

roadways and structures throughout the NPS park road 

system, including collecting data on location, number, 

size, condition, consequences of failure, and estimated 

cost of replacement or repair. This effort is designed to 

define and quantify the needs associated with these assets and to assist in developing a facility condition index 

for roadway assets. To date, 26 parks have been inventoried, with data collected on nearly 3,200 ERS estimated

to be worth $400 million if they were to be replaced in 

kind. Approximately 30 percent of the walls inventoried 

require some action such as immediate maintenance, 

repair, or replacement. The costs of the required work 

orders are estimated to be $10 million. Early identification of these maintenance and replacement needs will 

enable more efficient management of the assets and 

lower life-cycle costs. 

Benefits of Including ERS in Your 

Asset Management Plan 

•	 Make more informed, cost-effective program

decisions and optimize the use of existing highway 

funds and resources. 

•	 Maximize transportation system performance.

•	 Simplify tracking of roadway asset locations.

•	 Minimize life-cycle costs and maximize return

on investment. 

•	 Measure and analyze performance of like assets.

•	 Improve asset preservation through the use of

focused preventive maintenance efforts. 
 

 

 

 

	 	 	 	

	 	 	

 

	 	 	

	 	 	 	

	 	

	 	 	

	 	 	 	

	 	 	 	

Protecting the Future of Your 

Highway Infrastructure 

To learn more about how your agency can begin 

to implement AM techniques and data tools to 

protect your critical investment in ERS, maintain 

public safety, and maximize maintenance funding, see the following resources. Make the most 

of your ERS investment and ensure the future of 

your vital highway infrastructure by finding out 

what TAM can do for you today. 

Resources 

Contact 

Shyan-Yung Pan, P.E. 

FHWA Office of Asset Management

(202) 366-1567 (email:shyan.pan@dot.gov)

Online 

www.dot.state.co.us/publications/PDFFiles/

retainingwallmgt.pdf 

www.cincinnati-oh.gov/transeng/pages/-7054-/ 

www.oregon.gov/ODOT/TD/asset_mgmt/

docs/Committees/ExecSteeringCommittee/

31July2007/03D-Retaining_Walls_Asset_

Assessment.doc 

www.fhwa.dot.gov/infrastructure/asstmgmt 

http://assetmanagement.transportation.org 

Publications 

National Park Service Retaining Wall Inventory and 

Assessment Phase 1 Report, Federal Highway

Administration, Federal Lands Highway

Division, April 2005.

Feasibility of a Management System for Retaining 

Walls and Sound Barriers (Report No. CDOTDTD-R-2003-8), Colorado Department of

Transportation, Research Branch, May 2003.
Publication No. FHWA-IF-08-014