Transmission Lines: Issues Associated with High-Voltage 	 
Direct-Current Transmission Lines along Transportation Rights of 
Way (01-FEB-08, GAO-08-347R).					 
                                                                 
Electricity is central to the national economy and the daily	 
lives of many Americans, powering homes, businesses, and	 
industries. Today, an extensive system consisting of more than	 
150,000 miles of high-voltage transmission lines works to provide
reliable electricity service and transport electricity from power
plants to consumers. Federal and state entities share		 
responsibility for regulating the electricity system. On the	 
federal level, the Federal Energy Regulatory Commission (FERC)	 
regulates interstate transmission of electricity and wholesale	 
rates, among other regulatory activities. State public utility	 
commissions are generally responsible for regulating retail	 
electricity sales and, in some cases, planning for new power	 
plants and transmission lines. However, as studies have shown,	 
growth in electricity demand has strained the nation's		 
transmission system, resulting in less flexibility to respond to 
system problems and an increased risk of potential blackouts.	 
These issues have led some to suggest that new lines or other	 
investments in the transmission system may be required to	 
increase capacity and accommodate growing electricity demand.	 
Several companies have recently introduced proposals to build new
high-voltage direct-current (HVDC) transmission lines. Some of	 
these proposed lines would follow active transportation rights of
way, such as railroads, highways, and pipelines. Some		 
stakeholders have raised concerns about the potential economic,  
safety, and security issues related to collocating new HVDC	 
transmission lines along transportation rights of way,		 
particularly for nearby residents and consumers of electric	 
power. Given these issues, Congress included a provision in the  
Implementing Recommendations of the 9/11 Commission Act of 2007  
requiring us to assess the siting of HVDC transmission lines	 
along active railroad and other transportation rights of way and 
report to appropriate congressional committees. In response to	 
this requirement and after discussions with the committees, we	 
examined (1) the role of the federal government in siting HVDC	 
electric transmission lines along active transportation rights of
way, (2) advantages and disadvantages of adding transmission	 
lines and using HVDC technology, and (3) benefits and risks	 
associated with the siting of HVDC electric transmission lines	 
along active transportation rights of way.			 
-------------------------Indexing Terms------------------------- 
REPORTNUM:   GAO-08-347R					        
    ACCNO:   A80370						        
  TITLE:     Transmission Lines: Issues Associated with High-Voltage  
Direct-Current Transmission Lines along Transportation Rights of 
Way								 
     DATE:   02/01/2008 
  SUBJECT:   Electric energy					 
	     Electric power generation				 
	     Electric power transmission			 
	     Electricity demand 				 
	     Electricity restructuring				 
	     Energy consumption 				 
	     Energy demand					 
	     Energy development 				 
	     Energy industry					 
	     Energy management					 
	     Energy planning					 
	     Power transmission 				 
	     Public roads or highways				 
	     Rail (Railroads)					 
	     Regulatory agencies				 
	     Risk management					 
	     Strategic planning 				 

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GAO-08-347R

   

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United States Government Accountability Office: Washington, DC 20548: 

February 1, 2008: 

Congressional Addressees: 

Subject: Transmission Lines: Issues Associated with High-Voltage Direct-
Current Transmission Lines along Transportation Rights of Way: 

Electricity is central to the national economy and the daily lives of 
many Americans, powering homes, businesses, and industries. Today, an 
extensive system consisting of more than 150,000 miles of high-voltage 
transmission lines[Footnote 1] works to provide reliable electricity 
service and transport electricity from power plants to consumers. 
Federal and state entities share responsibility for regulating the 
electricity system. On the federal level, the Federal Energy Regulatory 
Commission (FERC) regulates interstate transmission of electricity and 
wholesale rates, among other regulatory activities. State public 
utility commissions are generally responsible for regulating retail 
electricity sales and, in some cases, planning for new power plants and 
transmission lines. 

However, as studies have shown, growth in electricity demand has 
strained the nation's transmission system, resulting in less 
flexibility to respond to system problems and an increased risk of 
potential blackouts.[Footnote 2] These issues have led some to suggest 
that new lines or other investments in the transmission system may be 
required to increase capacity and accommodate growing electricity 
demand. Several companies have recently introduced proposals to build 
new high-voltage direct-current (HVDC) transmission lines.[Footnote 3] 
Some of these proposed lines would follow active transportation rights 
of way, such as railroads, highways, and pipelines. Some stakeholders 
have raised concerns about the potential economic, safety, and security 
issues related to collocating new HVDC transmission lines along 
transportation rights of way, particularly for nearby residents and 
consumers of electric power. 

Given these issues, Congress included a provision in the Implementing 
Recommendations of the 9/11 Commission Act of 2007 requiring us to 
assess the siting of HVDC transmission lines along active railroad and 
other transportation rights of way[Footnote 4] and report to 
appropriate congressional committees. In response to this requirement 
and after discussions with the committees, we examined (1) the role of 
the federal government in siting HVDC electric transmission lines along 
active transportation rights of way, (2) advantages and disadvantages 
of adding transmission lines and using HVDC technology, and (3) 
benefits and risks associated with the siting of HVDC electric 
transmission lines along active transportation rights of way. 

To determine the federal government's role in siting HVDC electric 
transmission lines along active transportation rights of way, we 
reviewed applicable laws, regulations, and guidance related to siting 
new transmission infrastructure, including the Energy Policy Act of 
2005, the Federal Land Policy and Management Act, and FERC guidance. To 
identify the advantages and disadvantages of adding transmission lines 
and using HVDC technology, we reviewed relevant reports and studies, 
and we interviewed officials from the Departments of Energy, Homeland 
Security, and Transportation; officials from FERC, state public utility 
commissions, and state departments of transportation; and 
representatives from several other stakeholders, including electricity 
industry associations and independent system operators. To identify the 
benefits and risks of siting HVDC transmission lines along 
transportation rights of way, we reviewed literature to identify 
frequently cited benefits and risks of siting new HVDC electric 
transmission lines along active transportation rights of way for nearby 
residents and consumers of electric power. We also conducted site 
visits to three states--New York, Utah, and Virginia--where existing 
HVDC lines currently follow active railroad, highways, or pipelines, or 
where lines have been proposed that would do so. Finally, we 
interviewed officials from the Departments of Energy, Homeland 
Security, and Transportation; officials from FERC, state public utility 
commissions, and state departments of transportation; and 
representatives from a number of other stakeholders, such as power 
companies, transportation industry associations, and environmental and 
other advocacy groups to obtain their perspective on these issues. We 
focused our work on transmission line proximity to three types of 
transportation rights of way: railroads, highways, and pipelines. We 
conducted this performance audit from August 2007 to January 2008 in 
accordance with generally accepted government auditing standards. Those 
standards require that we plan and perform the audit to obtain 
sufficient, appropriate evidence to provide a reasonable basis for our 
findings and conclusions based on our audit objectives. We believe that 
the evidence obtained provides a reasonable basis for our findings and 
conclusions based on our audit objectives. We briefed committee staff 
on the results of our review (see enclosure I for a copy of that 
briefing). This report formally conveys the information provided during 
that briefing. 

Results in Brief: 

Historically, the federal government has had a limited role in siting 
transmission lines. It has generally only made siting decisions on 
federal lands. State governments, through public utility commissions 
and other agencies, traditionally approve transmission line siting. 
However, the Energy Policy Act of 2005 expanded the federal 
government's role. Specifically, under certain circumstances, FERC now 
has the authority to approve and issue siting permits for new 
transmission lines in areas designated by the Department of: 

Energy as National Interest Electric Transmission Corridors (NIETC). 
[Footnote 5] However, some stakeholders have expressed concerns about 
FERC's expanded authority in the national corridors, including how the 
state siting process will be affected and whether states and the public 
will be involved in FERC's proceedings. FERC officials told us they 
expect the review of a transmission line proposal in the national 
corridors would have little impact on the states' existing process. 
FERC officials also told us that to the extent FERC receives 
applications, they expect to consider information from the state siting 
process as part of their federal proceeding and that states and the 
public will have opportunities to participate in and comment on the 
federal siting process. Currently, federal statutes as well as federal 
and state guidance encourage the collocation of new transmission lines 
along existing transportation and other rights of way. For example, 
FERC guidance for hydroelectric projects provides that existing 
transportation and other rights of way should be given priority as 
locations for additional transmission facilities. FERC may be able to 
apply the principles from this guidance to transmission lines in the 
NIETCs. The type of transmission technology--either HVDC or high 
voltage, alternating current (HVAC)--does not affect how federal or 
state siting decisions are made. 

We identified potential advantages and disadvantages to adding 
transmission lines and using HVDC technology. According to studies we 
reviewed and stakeholders we interviewed, adding transmission lines 
offers potential advantages, including (1) decreased congestion and 
improved reliability of the electricity system by providing access to 
additional sources of generation and additional paths for electricity, 
(2) lower costs for consumers at the end of the line where electricity 
is received, (3) better utilization of existing power plants and more 
competitive local wholesale electricity markets, (4) facilitated 
development of new electricity sources location outside population 
centers, and (5) facilitated development of renewable energy sources. 
Stakeholders and studies also identified potential disadvantages of 
adding transmission lines, including (1) diminished economic or 
aesthetic values of the land if lines are built above ground, (2) 
raised electricity prices in areas from where the electricity is being 
taken, and (3) reduced incentives to identify alternatives that 
decrease demand (e.g., energy conservation). With respect to the 
potential advantages of using HVDC over HVAC technology, studies we 
reviewed and stakeholders we interviewed indicated that HVDC lines 
generally (1) cost less than HVAC over long distances and (2) allow 
operators of transmission systems to have more control over the 
direction and the amount of power flowing over HVDC lines. Potential 
disadvantages of using HVDC over HVAC technology include (1) higher 
costs for short-distance lines due to the cost of equipment needed to 
convert DC into AC electricity used by residents and (2) the lack of 
electricity benefits to consumers living along these lines--unless 
converter stations are installed at intermediate locations--because 
such lines are generally not connected to local electricity lines. 

We also identified potential benefits and risks resulting from the 
collocation of transmission lines along transportation rights of way. 
According to studies we reviewed and stakeholders we interviewed, 
potential benefits of collocation may include ease of construction and 
maintenance of the transmission lines and the reduction of 
environmental and visual impacts. For example, electricity stakeholders 
told us that building along rights of way may avoid constructing lines 
in undisturbed lands. In addition, stakeholders told us that it may be 
less costly to acquire the right to add a new transmission line to an 
existing right-of-way from a single owner--such as a pipeline, highway, 
or railroad--than it would be to acquire the needed rights from 
multiple property owners. Potential risks of collocation may include 
the increased likelihood of safety and security incidents due to the 
proximity of the transmission lines and the transportation 
infrastructure. For example, train derailments or highway crashes 
potentially could damage transmission lines and fallen transmission 
lines could damage transportation infrastructure. In addition, a 
collocated transmission line and natural gas line may be a more 
desirable terrorist target than either facility on its own. Federal and 
state officials told us they have not conducted studies specifically on 
these risks, but they expect the probability of these occurrences to be 
low. Several infrastructure owners and other stakeholders that we 
interviewed said that steps, such as adhering to required clearance 
distances for infrastructure maintenance and conducting risk 
assessments, can be taken to mitigate the potential risks associated 
with collocation. 

Agency Comments and Our Evaluation: 

We provided the Departments of Energy, Homeland Security, and 
Transportation, and FERC a draft of this report, including the slides, 
for review and comment. The Departments of Energy, Homeland Security, 
and Transportation, and FERC provided technical clarifications, which 
we incorporated as appropriate. 

We are sending copies of this report to the Secretaries of Energy, 
Homeland Security, and Transportation, the Commissioners of FERC, and 
other interested parties. We will also make copies available to others 
upon request. In addition, this report will be available at no charge 
on the GAO Web site at [hyperlink, http://www.gao.gov]. 

Should you or your staffs have any questions on matters discussed in 
this report, please contact Mr. Mark Gaffigan at (202) 512-3841 or Mr. 
David Wise at (202) 512-2834. Contact points for our Offices of 
Congressional Relations and Public Affairs may be found on the last 
page of this report. Key contributors to this report are listed in 
enclosure II. 

Signed by: 

Mark Gaffigan:
Acting Director, Natural Resources and Environment: 

Signed by: 
David Wise:
Acting Director, Physical Infrastructure: 

Enclosures: 

List of Congressional Addressees: 

The Honorable Daniel K. Inouye:
Chairman:
The Honorable Ted Stevens:
Vice Chairman:
Committee on Commerce, Science, and Transportation:
United States Senate: 

The Honorable Joseph I. Lieberman:
Chairman:
The Honorable Susan M. Collins:
Ranking Member:
Committee on Homeland Security and Governmental Affairs:
United States Senate: 

The Honorable Bennie G. Thompson:
Chairman:
The Honorable Peter T. King:
Ranking Member:
Committee on Homeland Security:
United States House of Representatives: 

The Honorable James L. Oberstar:
Chairman:
The Honorable John L. Mica:
Ranking Member:
Committee on Transportation and Infrastructure:
United States House of Representatives: 

The Honorable Michael A. Arcuri:
United States House of Representatives:
Briefing to Congressional Addressees: 

Enclosure I: 
Briefing to Congressional Addressees: 

Issues Associated with High-Voltage Direct-Current Transmission Lines 
along Transportation Rights of Way: 

Briefing to Congressional Committees: 

Contents: 

Objectives: 

Scope and Methodology: 

Summary: 

Background: 

Findings: 

Figure 1: HVDC Transmission Line along Utah State Highway 174 
(photograph): 

[See PDF for image] 

[End of figure] 

Objectives: 

The Implementing Recommendations of the 9/11 Commission Act of 2007 
required GAO to assess the siting of high-voltage direct-current (HVDC) 
electric transmission lines along active railroad and other 
transportation rights of way (ROW). 

To meet this requirement and address the interests of committee staff, 
we examined the following objectives: 

* What is the role of the federal government in siting HVDC electric 
transmission lines along active transportation ROW? 

* What are the advantages and disadvantages of adding transmission 
lines and using HVDC technology? 

* What are benefits and risks associated with the siting of HVDC 
electric transmission lines along active transportation ROW? 

Scope and Methodology: 

To answer the objectives, we: 

* reviewed applicable laws, regulations, and guidance to determine the 
federal governmentï¿½s role in the siting of HVDC electric transmission 
lines along active transportation ROW; 

* interviewed federal and state officials as well as representatives 
from other stakeholders, such as electricity industry groups and 
independent system operators, and reviewed reports and studies to 
identify the advantages and disadvantages of adding transmission lines 
and using HVDC technology; and; 

* conducted site visits and reviewed literature to understand the 
benefits and risks of siting HVDC electric transmission lines along 
existing transportation ROW for nearby residents and consumers of 

electric power. 

We focused our work on transmission line proximity to three types of 
transportation ROW: railroads, highways, and pipelines. 

For our site visits, we selected three statesï¿½New York, Utah, and 
Virginiaï¿½where existing HVDC lines currently follow active railroad, 
highways, or pipelines, or where lines have been proposed that would do 
so. 

Our findings represent the views of studies we reviewed and 
stakeholders we interviewed. 

We conducted our work from August 2007 through January 2008 in 
accordance with generally accepted government auditing standards. Those 
standards require that we plan and perform the audit to obtain 
sufficient, appropriate evidence to provide a reasonable basis for our 
findings and conclusions based on our audit objectives. We believe that 
the evidence obtained provides a reasonable basis for our findings and 
conclusions based on our audit objectives. 

Summary: 

In most cases, the federal government has a limited role in siting 
transmission lines: 

* State governments traditionally approve transmission line siting 
through public utility commissions and other agencies. 

* The Energy Policy Act of 2005 expanded the Federal Energy Regulatory 
Commissionï¿½s (FERC) federal role in siting transmission lines, under 
certain circumstances, within the National Interest Electric 
Transmission Corridors (NIETC). 

* Some stakeholders have expressed concerns about FERCï¿½s expanded 
authority to site transmission lines, including how states and the 
public will be involved in the siting process. 

* Federal statues as well as federal and state guidance encourage 
collocation of new transmission lines along existing transportation 
ROW. 

Potential advantages and disadvantages to adding transmission lines and 
using HVDC technology include: 

* Advantages of adding HVDC or high-voltage alternating-current (HVAC) 
transmission lines include decreased congestion and lowered costs to 
consumers; disadvantages include diminished land value if the lines are 
built above ground and reduced incentives to identify alternatives that 
decrease demand (e.g., energy conservation); 

* Advantages to using HVDC technology include lower costs over long 
distances and more system control; disadvantages include a lack of 
electricity benefits to those along its route and higher costs compared 
to construction of HVAC for short distances. 

Potential benefits and risks of transmission lines along transportation 
ROW include: 

* Benefits: easier construction and maintenance, and reduced 
environmental and visual impacts; 

* Risks: poses some safety and security risks; studies specifically on 
these risks have not been conducted, but probability of these 
occurrences expected to be low; several infrastructure owners and other 
stakeholders told us that steps can be taken to mitigate these risks. 

Background: 

HVDC Transmission Lines Are Uncommon in the United States: 

Electricity can be transmitted either using alternating-current (AC) or 
direct-current (DC). 

* AC is an electric current that reverses its direction at regular 
intervals; 

* DC is an electric current that flows in one direction through a 
circuit; 
- DC requires operator intervention to reverse the direction; 
- DC facilitates interconnection of AC at different frequencies. 

The United States electric grid relies primarily on AC technology: 

* There are five long-distance HVDC transmission lines; 

* HVDC represents about 2 percent of all transmission line miles. 

High-voltage transmission lines are usually 230 kilovolts (kV) or 
greater. 

There are proposals to build additional long-distance HVDC lines in New 
York and Virginia, among others. 

Figure 2: Map of Total AC and DC High Voltage Transmission Lines (less 
than or equal to 230kV) in the United States: 

[See PDF for image] 

This figure is a map of the United States depicting transmission lines. 
Lines are depicted with the following voltage levels (kV): 

230 kV;
345 kV; 
50o kV; 
765 kV; 
DC. 

Source: Federal Energy Regulatory Commission created using Global 
Energy's Energy Velocity Suite. 

Note: The 230, 345, 500, and 765 kV lines listed are all alternating 
current lines. 

[End of figure] 

Objective 1: 

What is the role of the federal government in siting HVDC electric 
transmission lines along active transportation ROW? 

Historically, the Federal Government Has Had a Limited Role in Siting 
Transmission Lines. 

* Generally, the federal government only makes siting decisions on 
federal lands. 

* State electricity agenciesï¿½such as the Public Utility Commissionï¿½ 
traditionally approve transmission line siting within their respective 
states. 

* The type of transmission technologyï¿½either HVDC or HVACï¿½does not 
typically affect how siting decisions are made. 

Federal Governmentï¿½s Role in Siting Transmission Lines Has Recently 
Changed. 

The Energy Policy Act of 2005 provided additional federal siting 
authority: 

* The Department of Energy designated two NIETCs in October 2007. 

* Within the NIETCs, FERC now has the authority to approve siting of 
new transmission lines under certain limited circumstances; that is,if: 
- The State does not have authority to approve siting or consider what 
the interstate benefits might be; 
- The applicant does not qualify for state approval since it does not 
serve consumers in that state; or; 
- The state entity with siting authority withholds approval for more 
than one year or conditions its approval such that the project will not 
significantly reduce interstate transmission congestion or is not 
economically feasible. 

* FERC issued rules specifying requirements for permit applications. 
[Footnote 6] 

* The Department of Energy is reviewing the applications for rehearing 
of its order designating the two NIETCs. 

Stakeholders Have Raised Questions about How FERCï¿½s Expanded Authority 
Will Function: 

Stakeholders we interviewed raised the following questions about FERCï¿½s 
expanded authority to site transmission lines: 

* What will be the impact on the current state siting process? 

* Will information from the state siting process be considered? 

* Will the state and the public have adequate opportunity to 
participate in and comment on the federal proceedings? 

In response, FERC officials told us that: 

* They expect their review of a transmission proposal in the NIETCs 
will have little impact on the stateï¿½s existing siting process; 

* To the extent FERC receives applications, they expect to consider 
information from the state process as part of the federal proceeding; 
and; 

* States and the public will have opportunities to participate in and 
comment on the federal siting process. 

Federal and State Statutes and Guidance Encourage Collocation with 
Existing ROW: 

Federal statutes and guidance encourage collocation of new transmission 
lines with existing transportation ROW. Examples include: 

* Federal Land Policy and Management Act (FLPMA) ï¿½to minimize adverse 
environmental impacts on federal land, the use of ROW in common is 
required to the extent practical; 

* Energy Policy Act of 2005 ï¿½requires streamlined review and permitting 
within corridors designated by FLPMA; 

* FERC guidance ï¿½for hydroelectric projects, existing ROW should be 
given priority as locations for additional electricity transmission 
facilities. FERC may be able to apply the principles from the guidance 
to transmission lines in the NIETCs. 

State guidance encourages collocation of new transmission lines. 
Examples include: 

* New York guidance ï¿½utility facilities should be accommodated within 
the highway ROW when such use and occupancy does not interfere with the 
free and safe flow of traffic; 

* Virginia guidance ï¿½cites FERCï¿½s guidance. 

Objective 2: 

What are advantages and disadvantages of adding transmission lines and 
using HVDC technologies? 

Adding Transmission Lines Has Potential Advantages: 

Studies we reviewed and stakeholders we interviewed identified the 
following potential advantages related to adding transmission lines: 

* May decrease congestion and improve reliability of the electricity 
system by providing access to additional sources of generation and 
additional paths for electricity; 

* May lower costs for consumers receiving the electricity; 

* May better utilize existing power plants and make local wholesale 
electricity markets more competitive (e.g., connecting existing,low-
cost power plants to areas with high power costs may increase 
competition and lower prices); 

* May facilitate development of new electricity sources located outside 
population centers, which sometimes face air quality and other 
environmental constraints; 

* May facilitate the development of renewable energy sources such as 
wind, water, solar, and geothermal energy, which may be located outside 
of urban centers. 

Adding Transmission Lines Has Potential Disadvantages: 

Studies we reviewed and stakeholders we interviewed identified 
potential disadvantages related to adding transmission lines: 

* May diminish economic or aesthetic land values if lines are built 
above ground (e.g., view of landscape may be affected); underground 
HVDC and HVAC lines are more expensive to construct and maintain than 
above-ground lines; 

* May raise electricity prices in areas from where the electricity is 
being taken; 

* May reduce incentives to identify alternatives that decrease demand 
(e.g., energy conservation). 

Using HVDC Technology Has Potential Advantages Compared to HVAC: 

Studies we reviewed and stakeholders we interviewed identified 
potential advantages of HVDC technology over HVAC technology: 

* HVDC generally costs less than HVAC over long distances (HVDC has few 
or no intermediate interconnections); 
- HVDC lines lose less power than HVAC lines; 
- HVDC lines may require less ROW width than HVAC (only two lines are 
needed for HVDC as opposed to three lines for HVAC); 

* HVDC lines can provide transmission operators with more control over 
the direction and amount of power flowing than HVAC lines. 

Using HVDC Technology Has Potential Disadvantages Compared to HVAC: 

Studies we reviewed and stakeholders we interviewed identified 
potential disadvantages of HVDC technology over HVAC technology: 

* Short-distance HVDC lines can be more expensive to construct than 
HVAC due to the need to convert direct-current into alternating-current 
electricity used by consumers; 

* HVDC lines do not typically provide electricity benefits to residents 
along their routes, unless converter stations are installed at 
intermediate locations, because such lines are generally not connected 
to local electricity lines. 

Objective 3: 

What are benefits and risks associated with siting HVDC electric 
transmission lines along active transportation ROW? 

Collocation Has Potential Benefits: 

Studies we reviewed and stakeholders we interviewed identified 
potential benefits: 

* Construction and maintenance: 
- May facilitate access to transmission lines for construction and 
maintenance; 
- May facilitate negotiation of a new ROW agreement; 
- May reduce the need to designate a new ROW in residential, 
commercial, and industrial areas where limited space is available for 
transmission lines. 

* Environmental and visual: 
- Can avoid impacting undisturbed land and surrounding areas. 

* Economic: 
- Use of existing single ROW may be less costly than acquiring new 
property rights or property from multiple owners; 
- Current owner of ROW may benefit from payment for additional use of 
ROW. 

Collocation Has Potential Risks: 

Studies we reviewed and stakeholders we interviewed identified 
potential safety and security risks; 

* Safety: 
- Accidents from transportation infrastructure users (such as train 
derailments or highway crashes) could damage transmission lines and 
fallen transmission lines could damage transportation infrastructure; 
- Electromagnetic fields and stray current could interfere with 
railroad signaling systems and highway traffic operations, and 
accelerate pipeline corrosion, resulting in accidents; 
- Maintenance workers may be more likely to be injured given increased 
safety risk from close proximity of transmission lines to 
transportation ROW; 

* Security: 
- Collocation may make the corridor a more attractive target; 
- Events that would otherwise be isolated (e.g., a pipeline explosion) 
could lead to service interruptions on the transmission line or along 
active ROW. 

Federal and state officials we interviewed told us that while they have 
not conducted studies specifically on these risks, they expect the 
probability of these occurrences to be low. 

Steps Can Be Taken to Mitigate Potential Risks of Collocation: 

Various stakeholders, including industry associations and 
infrastructure owners, reported that steps can be taken to mitigate 
potential risks associated with collocation. 

Examples of approaches for mitigating potential collocation risks 
include: 

* Along pipelinesï¿½Ensure electric current emitted from the line will 
not interfere with cathodic protection (which helps to prevent 
corrosion) required under Pipeline and Hazardous Materials Safety 
Administration regulations, or otherwise directly or indirectly 
accelerate pipeline corrosion; 

* Along railroads ï¿½Ensure lineï¿½s magnetic fields will not interfere 
with railroad signal systems; tower design must adhere to required 
clearances for maintenance; 

* Along highways ï¿½Encourage assessments of potential collocation risks; 
Ensure transmission towers and lines will not impede traffic operations 
and the free flow of traffic or possible future expansion of roadway. 

[End of enclosure] 

Enclosure II: 

Staff Acknowledgments: 

Key contributors to this report were Nikki Clowers, Assistant Director; 
Jon Ludwigson, Assistant Director; Vidhya Ananthakrishnan; Allen Chan; 
Colin Fallon; Philip Farah; Kathleen Gilhooly; Brandon Haller; Dawn 
Hoff; Tina Won Sherman; and Barbara Timmerman. 

[End of enclosure] 

Footnotes: 

[1] High-voltage transmission lines carry currents of usually 230 
kilovolts or greater. 

[2] See U.S. Department of Energy, National Transmission Grid Study 
(May 2002) pp. 5-6; Congressional Research Service, Electric 
Transmission: Approaches for Energizing a Sagging Economy (Apr. 27, 
2007) pp. 1-2; and National Council on Electricity Policy, Electricity 
Transmission: A Primer (June 2004) pp. 6-7. 

[3] DC technology is defined as current that flows in one direction 
through a circuit and requires operator intervention to reverse the 
direction. The majority (98 percent) of all transmission line miles in 
North America use alternating current (AC) technology, whereby the 
current reverses direction at regular intervals without operator 
intervention. DC can be converted into AC, and vice versa, using a 
converter station. 

[4] Pub. L. No. 110-53, ï¿½ 1525 (Aug. 3, 2007). 

[5] As required by the Energy Policy Act of 2005, the Department of 
Energy established NIETCs in October 2007, within which FERC now has 
the authority to approve siting of new transmission lines under certain 
circumstances; that is, if: (1) the state does not have authority to 
approve siting or consider what the interstate benefits might be; (2) 
the applicant does not qualify for state approval since it does not 
serve consumers in that state; or (3) the state entity with siting 
authority withholds approval for more than 1 year, or conditions its 
approval such that the project will not significantly reduce interstate 
transmission congestion or is not economically feasible. See Pub. L. 
No. 109-58 ï¿½ 1221(a) (Aug. 8, 2005). FERC issued rules specifying 
requirements for permit applications. See FERC Order No. 689, 
Regulations for Filing Applications for Permits to Site Interstate 
Electric Transmission Facilities. The Department of Energy is reviewing 
the applications for rehearing of its order designating the two NIETCs. 

[6] See FERC Order No. 689, Regulations for Filing Applications for 
Permits to Site Interstate Electric Transmission Facilities. 

[End of section] 

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