Hurricane Evacuation Plan Phase One-1984

HURRICANE EVACUATION
PLAN
Phase One = An Analysis of Evacuation
Capability and Vulnerability to Hurricanes in
New Hanover County
JUNE 1984
Prepared by the New Hanover County Planning Department
DCM COPY DCM COPY
lease do not remove!!!!!
Division of Coastal Management
Hurricane Wind Direction

HURRICANE EVACUATION PLAN
Phase One - An analysis of evacuation capability and
vulnerability to hurricanes in New Hanover County
JUNE, 1984
Prepared by the New Hanover County Planning Department
The preparation of this document was
financed, in part, through a Coastal
Area Management Act grant provided by
the North Carolina Coastal Management
Program, through funds provided by the
Coastal Zone Management Act of 1972, as
amended, which is administered by the
office of Coastal Zone Management,
National Oceanic and Atmospheric
Administration
-Figure on cover from Simpson, R., and H. Riehl, 1981, The Hurricane and It's
Impact, Baton Rouge, LA, Louisiana State University Press.

TABLE OF CONTENTS
I. PURPOSE AND SCOPE
II. THE HURRICANE THREAT
A. Background
B. Potential Hurricane Impacts
C. Hurricanes and New Hanover County
III. THE SEVERITY OF EXPOSURE OF NEW HANOVER COUNTY TO HURRICANES
IV. ANALYSIS OF EVACUATION
A. Components of Hurricane Evacuation Time
B. Evacuation Times for New Hanover County
V. ANALYSIS OF EVACUATION SHELTERS
VI. CONCLUSIONS AND RECOMMENDATIONS
V. REFERENCES
Page No.
1
1
1
2
6
6
13
13
14
19
19
20

HURRICANE EVACUATION PLAN
I. PURPOSE AND SCOPE
This Hurricane Evacuation Plan analyzes the capability of expected
evacuation routes and shelters to safely accommodate the evacuation of County
residents from hurricane -vulnerable areas. This Plan represents the major
product of the first year of a two-year comprehensive, Countywide planning effort
that will result in an overall "Hurricane Hazard Mitigation and Post Disaster
Plan". This plan is being funded by a grant from the North Carolina Office of
Coastal Management under authority of the Coastal Area Management Act (LAMA).
The products of this -two-year planning study will be:
1. Hurricane Evacuation Plan (year one)
a. hazard area map
b. analysis of expected evacuation routes
c. assessment of existing evacuation routes and sites
d. proposed mitigation policies if sites and routes are assessed
to be inadequate
e. up -dating of the operational elements of the existing
"Hurricane Evacuation Plan", prepared by the New Hanover
County Civil Preparedness Agency.
2. Preparation, printing and distribution of evacuation instructions
and hurricane season warning poster (year one)
3. Storm Hazard Mitigating Plan (year two)
a. Inventory and analysis of existing land uses and structures
in the hazard areas
b. Economic risk assessment
c. Hazard Mitigation policies based on 3a and 3c.
4. Post Disaster Reconstruction Plan (year,two)
a. Guidelines for post disaster reconstruction including the
phasing of damage assessment, temporary moratorium, and post
disaster development standards
b. Establishment of damage assessment teams and standards.
II. THE HURRICANE THREAT
A. BACKGROUND
A hurricane resembles a large, shallow funnel with air flowing in a counter
clockwise direction from high pressure areas along the storm's periphery to a
concentrated center of extremely low pressure. Winds may reach 200 miles per
hour near the center of the hurricane, even though the center, or the "eye", is
an area of relative calm.
Page 1

Atlantic hurricanes generally begin as low intensity storm systems in the
Carribean Sea or the Western Atlantic Ocean. Hurricanes form by passing through
increasingly intense phases:
-tropical depression (winds less than 40 miles per hour)
-tropical storm (winds between 40 and 73 miles per hour)
-hurricane (winds greater than 73 miles per hour)
Although the hurricane season runs from June through November, 90% of all
recorded hurricanes in North Carolina have occurred in August, September, and
October. Hurricanes tend to follow a westward parabolic path and generally move
forward at a speed of around 15 miles per hour. Both the direction and the
forward spead of the hurricane path, however, can vary dramatically (McElyea et
al, 1983).
Presently, local governments in New Hanover County have the responsibility
of ordering evacuation based on their judgement that a hurricane is threatening.
The local governments generally use the Hurricane Watch and Warning system of the
National Weather Service as signals for action. A Hurricane Watch is issued when
a hurricane is near enough that everyone in the area should listen for subsequent
advisories and be ready to take action. The National Weather Service issues.a
Hurricane Warning when hurricane conditions are considered to be highly likely.
The goal of the Service is to issue the warning at least 12-18 hours before the
hurricane eye reaches the area. The Hurricane Warning generally is the signal
used by local governments to order evacuation.
Attempting to predict the path and travel time of a hurricane is complicated
by the tendency of the hurricane to vacillate significantly along its path, by
the large approximately 125 mile diameter of a hurricane, and by a lack of
recorded data'on previous hurricanes. The National Weather Service has recently
developed a probability system in hurricane forecasting. This system gives the
probability increments, in percentages, of a hurricane eye gaining landfall
within 65 miles of a given community for five time periods: (1) through 24
hours, (2) 24-36 hours, (3) 36-48 hours, (4) 48-72 hours, and the total
probability through 72 hours. These probabilities, however, are not related to
the intensity of the storm. This new probability system presently operates in
addition to and independent of the Hurricane Watch and Warning System (Carter,
1983).
B. POTENTIAL HURRICANE IMPACTS
Since the turn of the century, casualties from hurricanes have generally
decreased due to improvements in monitoring and warning systems and local
preparedness and evacuation planning. The potential for substantial loss of.life
remains, however, as coastal population increases and the tourism traffic grows.
Property damage, in contrast to casualties, has increased exponentially. These
trends are shown in Figure 1.
Hurricanes are typically classified according to the Saffir/Simpson Damage
Potential Scale. Hurricanes are designated on a scale of 1 to 5 (described in
Table 1) based on the hurricanes present wind speed, storm surge level, and
atmosphere pressure.
Page 2

Additional hurricane factors causing casualties and damage include wave
action and erosion.
(1) Wind damage
Wind strengths will increase as the hurricane center approaches
land. Peak gusts may exceed 200 miles per hour. Friction from the
land surface will generally dissipate high winds although a narrowing
zone of wind damage, 30-35 percent of that at the shoreline, can
extend much further inland. In addition, tornadoes may occur with
the hurricane. Hurricane Agnes, for example, spawned 15 tornadoes
in Florida, resulting in 4.5 million dollars of damage (McElyea et al
1983).
(2) Flooding Damage
Approximately 90% of hurricane deaths and the majority of property
damages result fran flooding caused by hurricane storm surges and
precipitation. The storm surge results from the hurricane winds
and low pressure system pushing up an enormous swell of water
before it. The height of the surge depends on wind speed, normal
water depth, storm trajectory, forward speed of the storm,
and tide conditions. Hurricane Hazel in 1954 created a surge of
14.7 feet above mean sea level at Holden Beach. The increase in
flood elevation may be 50% greater behind the barrier islands due to
funneling of the water in shallow and narrow estuaries and bays.
Flooding damage is worsened by the lifting up and use of debris,
boats, and structures as battering rams. Saltwater contamination
of land may result. Precipitation, adding to the flooding problems,
may equal 10" or more in a 24 hour period (McElyea et al 1983)
(3) Wave Action
The impacts of the storm surge are increased greatly by the effects
of waves. First, waves on top of a surge can reach and flood areas not
reached by the surge itself. Second, waves act as direct battering
rams, their force depending-upn the velocity and size of waves. The
waves are likely to be greatest along the ocean shoreline where winds
are greatest and where the ocean bottan falls off rapidly. Generally,
the waves height will be equal to 50% of the depth of the storm surge
(McElyea, et al 1983).
(4) Erosion
High winds, storm surge, and waves may cause significant erosion,
especially on barrier islands. Vast amounts of sand may be removed
from the beach front. Dunes may be breached by washover fran waves.
Finally, inlets tend to form or widen in response to storm surge
build-up behind the barrier island. In 1967, Hurricane Beula cut 31
inlets through Padre Island, Texas. Although many of the inlets may
eventually fill back in, the damage to structures and transportation
networks will already have occurred.
Page 3

DAMAGE
BY FIVE YEAR PERIODS IN MILLIONS OF DOLLARS (VALUES ADJUSTED TO
BASE 1957-591
A
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O
O
O
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0
ob O O O O
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O
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O O O
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1915 -19
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1920-24
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1925-29
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1930-34
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:
1935-39
3w
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1940-44
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C
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1945-49
a
0
a.-n
1950-54
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m
1960-64
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2.448
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1900-04
0000 Plus
1905-09
1910-14
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1930-34
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1940-44
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1945-49
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1950-54
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1955 59
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DEATHS CAUSED IN THE UNITED STATES BY HURRICANES
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Table " 1: Saffir/Simpson Damage Potential Scala
Scale No. 1—Winds of 74 to 93 miles per hour. Damage primarily to shrubbery.
trees. foliage. and unanchored mobile homes. No real damage to other structures.
Some damage to poorly constructed signs. And/or: storm surge 4 to 3 fed above
normal. Low-lying coastal roads inundated, minor pier damage, some small haft
in exposed anchorage torn from moorings.
Seale No. 2—Winds of 96 to 110 miles per hour. Considerable damage to shrub-
bery and tree foliage; some trees blown down. Major damage to exposed mobile
'homes. Extensive damage to poorly constructed signs. Some damage to roofing
materials of buildings: some window and door damage. No major damage to
buildings. And/or: storm surge 6 to 8 feet above normal. Coastal roads and low-
lying escape routes inland cut by rising water 2 to 4 hours before arrival of
hurricane center. Considerable damage to piers. Marinas flooded Small craft in
unprotected anchorages torn from moorings. Evacuation of some shoreline resi-
dences and low-lying island areas required.
Sale No. 3—Winds of I I I to 130 miles per hour. Foliage torn from trees+ faros
trees blown down. Practically all poorly constructed signs blown down. Some
damage to roofing materials of buildings; some window and door damage. Some
structural damage to small buildings. Mobile homes destroyed. And/or: storm
surge 9 to 12 feet above normal. Serious flooding at coast and many smalkr
structures near coast destroyed; larger structui near ocest damaged by battering
waves and floating debris. Low-lying escape routes inland cut by rising water 3
to 3 hours before hurricane center arrives. Flat terrain 3, feet or lea above sea
level flooded inland 8 miles or more. Evacuation of law4ying residences within
several blocks of shoreline possibly required.
Sale Na 4—Winds of 131 to 133 miles per hour. Shmbe and trees blown down;
all signs down. Extensive damage to roofing materials, windows and door. Cam-
plele failure of roofs on many small residences. Complete destructions ^( mobil
homes. And/or. storm surge 13 to 19 feet above normal. Flat krrain'IU feet or
less above sea level flooded inland as far as 6 miles. Major damage to lower
floors of structure near shore due to flooding and battering by waves and floating
debris. Low-lying escape routes inland cut by rising water 3 to 3 hours before
hurricane center arrives. Major erosion of beaches. Massive evaeustm of all
residences within 500 yards of shore possibly required, and of singlastory resi-
dences on lover ground within 2 miles of shore.
Seals No. S—Winds greater than 133 miles per hour. Shrubs and trees blows
down; considerable damage to roofs of buildings; all signs dawn. Very ar"re
and extensive damage to windows and dw . Complete failure of roots on marry -
residences and industrial buildings. Extensive shattering of giasa in windows sad
doors. Some complete building failures. Small buildings overturned or blown
away. Complete destruction of mobile homes And/or: storms sure greater than
18 feet above normal. Major damage to lower !loon of all structures less than
13 feet above sea level within 300 yards of shore. Low-lying escape raria inland
cut by rising water 3 to 3 boors before hurricane terser arrives. Massive evacus-
tion of residential areas on low ground within 3 to 10 miles of shore possibly
required.
Source: (McElyea et al, 1983)
Page 5

C. HURRICANES AND NEW HANOVER COUNTY
Since 1899, North Carolina has received direct hits from 21 hurricanes,
eight of them classified as "major" (3, 4, or 5 on the Saffir/Simpson Scale).
Numerous other hurricanes have also impacted North Carolina, including lesser
hurricanes and hurricanes staying out at sea br hitting South Carolina. As
indicated in Figure 2, New Hanover County has approximately a 6% chance of being
directly struck by a hurricane any given year. As indicated in Table 2, a number
of hurricanes have either directly or indirectly impacted New Hanover County
beaches in the 20th Century (USCOE, 1983). It should be noted that certain
impacts such as erosion along beaches may be caused by indirect impacts of
hurricanes or of lesser storms, such as "northeasters."
An account of Hurricane Hazel when it struck North Carolina on October 15,
1954, illustrates the impacts caused by a hurricane. The storm surge exceeded 14
feet and wind velocities were estimated at 140 miles per hour. Every fishing
pier in North Carolina was destroyed. All buildings were destroyed at Holden
Beach and Ocean Isle. At Long Beach, 352 of 357 homes were lost. At Carolina
Beach, 475 buildings were destroyed and 1,365 were damaged. Over 1,000,000 cubic
yards of sand were deposited on Carolina Beach roads. Wrightsville Beach was
submerged under five feet of water and 89 homes were lost. A total of 191 people
were killed in the State and $125,309,000 of damage were caused (McElyea, 1983).
III. THE SEVERITY OF EXPOSURE OF NEW HANOVER COUNTY TO HURRICANES
All of New Hanover County is vulnerable to hurricane forces to a varying
degree, as evidenced by Table 3. The entire County will be subject to possible
wind damage. However, certain areas will be highly exposed to shoreline erosion
and scouring, wave action and battering, and flooding, in addition to direct wind
damage. These areas, which have a severity rank of one, are Ocean Erodible Areas
of Environmental Concern (AECs), Inlet Hazard AECs, and Estuarine Shoreline AECs.
These areas are the most critical areas for hurricane protection planning with
regard to exposure to hurricane forces.
Ocean Erodible AECs start at mean low water and go landward a distance from
the vegetation line equal to 30 times the long term annual erosion rate plus the
shoreline recession projected for a 100 year storm. This width generally varies
between 200-400 feet. Inlet Hazard AECs are based on statistical analysis of
inlet migration (using a 99.9% confidence interval for a 10 year period) and such
factors as man-made alterations or unusual hydrologic features. The width of
this area may vary from as little as 250 feet for stable inlets to 4,000 feet in
more dynamic areas. This hazard area applies only to existing inlets, not to
past or potential inlets (Owens, 1981). Detailed maps prepared by the U. S.
Corps of Engineers and the N. C. Office of Coastal Management at a scale of 1" _
400' are available for review at the County Planning Department.
Page 6

i
Figure 2 Percentage Probability that a Hurricane
(winds exceeding 73 mph) or a Great Hurricane
(winds exceeding 125 mph) Will Strike a
50-Mile Segment of the U. S. Coastline
in any Given Year.
r--
r 1
•
•
_ •• 7 b6913
u
1• 17t18 21 330 0 ,n
7 6 7 n 2. 21 �1
0 20 2•
. zl •-
s 22 - ^ : 232 i .
4 p ALL HURRICANES l� .5 9 13 \3 b
3 4 ♦ J' i''- ti o
2 GR T HUSRICANES ) 2 a 'LD
VS
Source: .(McElyea et al, 1983)
Page 7

Table 2
HISTORICAL RECORDS Source: (USCOE, 1982)
1. Lists of Hurricanes.
The following tables present a chronological
list
of tropical hurricanes
which have likely affected the Wrightsville
Beach
area.
However, many of
them caused no appreciable damage
and others
prior
to 1871, which caused some damage, may not be listed:
Records
of 18th and 19th Century Hurricanes
Affecting the North Carolina Coastal Area
Date
Date
Year,
Month, and
Day
Year,
Month, and
Day
18th Century
19th
Century (cont'd)
1700
September
16
1844
September
14
1713
September
16
1846
August
16
1728
August
-
1853
September
1728
September
14
1854
September
8
1752
September
15
1857
September
12
1753
September
15
1861
October
-
1757
October
-
1871
August
18-19
1758
August
23.
1871
November
14
1761
June
1
1873
September
22-24
1761
September
23
1873
October
6-8
1770
June
6
1873
November
17
1781
August
10
1874
September
28
1783
-
-
1874
November
22
1785
September
22-24
1875
October
13
1797
September
-
1876
September
17
1877
November
2
191th Century
1878
September
12
1878
October
22
1804
September
7
1879
August
19
1811
September
10
1880
August
15
1813
August
27
1881
August
27
1814
July
1
1881
September
9
1815
September
28
1883
September
11
1821
September
2
1885
August
24-25
1822
August
-
1888
October
11
1822
September
27
1893
August
28
1827
July
30
1893
October
13
1827
August
24-25
1894
September
27
1830
August
16
1894
October
9
1837
August
1
1896
September
20
1837
August
20
1897
November
7
1837
October
9
1898
October
2
1838
November
26-28
1899/October
30
1842
August
24
Page 8

Table 2 cont.
Records of 20th Century_ Hurricanes Affecting
New Hanover County, N.C., Beach Areas
Year
Month and Day
Notes, Severit , Damage Areas, etc.
Major and Moderate
11904
September 14
Moderate, S.E.N.C.
1904
November 13
Moderate, N.C. coast
11906
September 17
Severe, S.E.N.C. Barometer at Wilm., 27.90
1910
October 19
Moderate, Wilmington area - inland
11913
September 2-3
Hatteras - major, N.E.N.C.
1916
July 19-20
Moderate, N.E.N.C. Heavy rainfall
1918
August 24
Hatteras, moderate, small, N.E.N.C.
1924
August 25
Moderate, skirted N.C. at Hatteras
11925
December 2
Moderate, N.E.N.C. Unusual storm
Barometer 28.90 near Wilmington
1930
September 12
Hatteras and vicinity - moderate.
Barometer 29.71 at Wilmington.
11933
September 16
Severe N. of New Bern to Va. Capes,
moderate to minor elsewhere. Barometer at
Hatteras, 28.25 inches.
1934
July 21-25
Very minor in vicinity of Wilmington
11944
August 1-2
Wilmington - severe, S.E.N.C. Barometer
at Wilmington, 29.41
11944
September 14
Hatteras - severe. Barometer at Hatteras,
27.97.
1945
September 15-16
Beaufort area - moderate.
1954
August 30
Moderate to light - whole coast - "Carol"
Barometer 29.41 at Wilmington.
11954
October 15
Very severe, S.E.N.C. "Hazel." Barometer,
27.70 at Little River, S.C.
1 Storms actually striking or entering N.C. coast with destructive force.
Page 9

Table 2 cont.
Records of 20th Century Hurricanes Affecting
New Hanover County, 'N.C., Beach tireas
Year
Month and Day
Notes, Severitv, Damage Areas, etc.
Major and Moderate -- Cont'd
11955
August 11-12
Severe, E.N.C., heavy rains - "Connie."
Barometer, 28.40 at Fort Macon, N.C.
11955
August 17
Moderate in Wilmington Area - "Diane."
Barometer, 29.13 at Wilmington, N.C.
11955
September 19
Severe, E.N.C., excessive precipitation.
Barometer, 28.35, at Morehead City, N.C.
"Ione."
11958
September 27
"Helene." Severe in Cape Fear area.
Maximum 5-minute wind, 69 mph. Minimum
barometer 28.80 inches - both at Wilm., N.C.
11960
September 11-12
"Donna." Severe in Cape Fear area, worse in
vicinity of Morehead City, N.C. Maximum 1-
minute wind velocitv'in Wilmington, 53 mph,
NW; minimum barometer 28.41 inches.
Minor
1901
September 18
1902
June 16
1903
September 16
Very minor - delayed flight of Wright Brothers
1908
August 31
Cape Lookout damaged - very unusual storm.
1916
July 14
Heavy rain in interior.
11920
September 20
Cape Fear River area - small storm - little
damage.
1923
October 23
1924
September 16-17
1924
September 30
Minor in Wilmington area.
1928
September 18
S.E.N.C. Barometer, 29.12 at Wilmington, N.C.
Page 10

Table 2 cont.
ear
1929
1934
1935
1937
1937
1937
1938
1938
1940
1940
1942
1944
1945
1945
1946
1946
1947
1950
1951
1952
1953
1954
1973
1979
Records of 20th Century Hurricanes Affecting
New Hanover County, N.C., Beach Areas
ith and Day Notes, Severity, Damage Areas, etc.
September 1-2
September 7-8
September 5-6
July 31
August 2-8
September 26-30
September 21
October 23-24
August 15
September 1
October 11-12
October 20
June 24
November 5
July 6
September 19
October 12-13
August 19-20
October 4
August 30
August 13
September 10
February 17
September 5
Minor -- Cont'd
Very minor
Barometer at Hatteras, 28.56
Minor, not a hurricane in N.C.
Minor, not a hurricane in N.C.
Minor, not a hurricane in N.C.
Hatteras and vicinity
Minor, not a hurricane in N.C.
Very minor, heavy rain
Heavy rains
Very minor, not a hurricane in N.C.
Very minor
Very minor
Minor
Very minor "Able."
"Barbara" Cape Lookout area.
"Edna"
Erosion and some property damage
"David" 1-year frequency storm
Page 11

Table 3
Severity of Risk in Hazard Areas
Hazard Area
Exposure to Damaging Forces
Severity
Rank
Erosion/
Scour
Wave Action/
Battering
Flooding
High
Wind
ocean Erodible AEC
1
0
0
0
0
Inlet Hazard AEC
1
0
0
0
0
Estuarine Shoreline AEC
1
0
0
0
0
V-zone
2
0
0
0
0
Wetland AEC -
2-
0
0
0
0
A -zone
3
0
0
Rest of Community
4
0
Exposure Level: High (a), Moderate (o), Low ( )
Source: (McElyea et al, 1983)'
Page 12

The Estuarine Shoreline*AEC's cover all land within 75 feet of the mean high
water line. Estuarine lands may be subject to storm surge and general flooding.
Federal Flood Insurance V zones, which tend to overlap the above AECs, represent
those areas likely to be flooded by a 100 year storm and exposed to scouring
/erosive wave action. Coastal Wetland AECs, located generally within the
Estuarine Shoreline AEC, are low lying areas and would tend to be flooded.
Federal Flood Insurance A Zones are likely to be inundated in a 100 year storm
but would not be subject to scouring/erosive wave action. The extent of the
Estuarine Shorelines and Coastal Wetlands are mapped on Figure 4. (attached as
fold -out maps in the back of this report) A more detailed map at 1" = 3000' is
available for review at the County Planning Department. The extent of the V and
A zones are mapped on Figure 5. (attached as fold -out maps in the back of this
report) Maps at a scale of 1" = 2000' prepared by Federal Emergency Management
Agency (FEMA) of the V and A zones are available for review at the County
Planning Department.
IV ANALYSIS OF EVACUATION TIME
A. COMPONENTS OF HURRICANE EVACUATION TIME
Evacuation time is defined as
"...the minimum amount of time before projected hurricane
eye landfall that local decision makers must allow for
safely completing the evacuation under the particular
conditions of the approaching hurricane." (Stone, 1983, p. 7)
Evacuation time is composed of two separate components, clearance time and
pre -landfall hazards time.
(1) Clearance Time
Clearance time is defined as the time, necessary for the relocation of
all vulnerable evacuees to a safe area once the official evacuation
order is issued. Clearance time is composed of three subcomponents:
mobilization time, travel time, and queuing delay time..
(a) Mobilization time is that period between the issuance of the
evacuation order and the departure of the vehicles. It represents
time for evacuees to learn of the evacuation order, pack some
belongings and leave. Three hours/household for mobilization is a
typical time period used in other studies and corresponds with
preliminary survey results of residents and tourists during August
and September, 1983, on Wrightsville, Carolina and Kure Beaches.
Page 13

(b) Travel time is the period necessary for the vehicles to travel the
length of the evacuation route at an anticipated speed, assuming
no queuing delays
(c) Queuing delay time is the amount of time spent by vehicles in
traffic jams when the capacity of the evacuation routes are
exceeded by the number of vehicles entering those routes. A
bottleneck would occur, for instance, where four lanes converge
onto a two lane bridge.
The roadway capacity factors for the study, taken from the carrying
capacity study for Currituck (Collins, 1983) are 1575 vehicles per hour (vph) for
two lane roads and 3222 vph for a four lane road. These levels of capacity would
increase for roads with shoulders or parking lanes. These factors take into
account the following adjustments:
- common roadway capacity standards for engineering purposes
- 35% reduction in capacity due to adverse weather
- 15% further reduction for stalled cars
- 10% further reduction for emergency vehicle use
It should be noted that traffic during evacuation should be strictly
controlled, using policemen for directing traffic and generally requiring one way
traffic.
(2) Pre -Landfall Hazards Time
This represents the period of time between when evacuation
from the vulnerable area first becomes extremely difficult
due to either gale force winds or storm surges that inundate
evacuation routes, and when the eye of the hurricane reaches
the coast. A typical value for a severe hurricane scoring a "5"
on the Saffir/Simpson Scale.is four hours. This amount of time
plus clearance time equals evacuation time.
B. EVACUATION TIME FOR NEW HANOVER COUNTY
A conservative analysis of the components of evacuation time is presented
below for Wrightsville Beach, for the area south of Snow's Cut, and for Figure
Eight Island. Although other areas in the County along the sounds, creeks, and
rivers are within hazard areas (estuarine shoreline and 100-year flood plain),
evacuation for these areas are considered to be adequate because of the short
length of the evacuation routes, lack of bridges, and low concentrations of
population served by the routes.
The analysis utilizes methods and assumptions drawn from work developed
by the State Office of Coastal Management (McElyea, et al 1983), the Sea Grant
Program at NCSU (Stone, 1983), and an analysis prepared for Currituck County
(Collins, 1983). The analysis assumes the following "worst case" scenario:
Page 14

A severe hurricane, measuring five on the Saffir/Simpson
Scale, has suddenly shifted direction and is heading
rapidly toward New Hanover County. The eye of the
hurricane is expected to reach land within 12 hours.
The National Weather Service has issued a Hurricane
Warning and the County's local governments have
correspondingly issued evacuation orders. Can the
beaches be evacuated in a safe and timely manner?
The analysis below is considered conservative because of certain
assumptions concerning traffic flow and because, in reality, up to 30% of the
short-term renters and residents would likely leave before the evacuation order
is issued (Stone, 1983).
Total Evacuation Time = Total Clearance + Pre -Landfall Hazard
Time Time
= 6.61 hours + 4 tours
= 10.61 tours
The total evacuation time of 11 hours indicates that Wrightsville Beach
could be safely evacuated if evacuation is ordered concurrent with a typical 12
hour advance Hurricane Warning. This conservative estimate includes
Total Clearance Time = Mobilization + Travel + Queuing Delay
Time Time Time
= 3 hours + .25 hours/l + 3.36 hours/2
= 6.61 tours
/1Taavel Time: Under free flow traffic conditions, a car
should be able to travel from any point on Wrightsville
Beach to the mainland in a maximum of 15 minutes.
/2Queuing Delay Time: Queuing delays will result from
vehicles coming from residential streets onto Highways
74 and 76 (Waynick Blvd., Lumina Ave., and Causeway Dr.).
It is assumed that traffic coming off the drawbridge onto
the mainland will be controlled to prevent traffic back-up
Calculations are given below:
Page 15

-Assume that a total of 3150 households and motel room
groups require evacuation. Each has an average of 1.6
vehicles per household, for a total of 5040 vehicles.
-Assume that one half (2200) of the vehicles will
evacuate from the southern end of the Beach and more than
one half (2840) simultaneously from the northern end, along two-
lane roads. The number of vehicles evacuating from the
northern end include those from the anticipated development
from Shell Island. For simultaneous evacuation of households
along those two separate, two-lane stretches of road, therefore,
maximum queuing delay time would be determined by the larger of
the two:
Queuing 2840 vehicles
delay = 1575 vph capacity
time
= 1.8 hours
-Assume that all vehicles (5040) must travel on a four lane
road to the mainland. This maximum queuing delay time would
equal:
Queuing 5040 vehicles
delay = 3232 vph capacity
time
= 1.56 hours
-The Wrightsville Beach drawbridge, according to the N. C. Dept.
of Transportation, will not be opened during high winds and,
therefore, would not be a significant delay in traffic.
-Total maximum = 1.8 hours + 1.56 hours
Queuing delay time
= 3.36 hours
Total Evacuation = Total + Pre -landfall
Time Clearance Hazards
Time Time
= 6.22 hours + 4 hours
= 10.22 hours
The total evacuation time of 10.22 hours indicates that this area of the
County could be safely evacuated if evacuation is ordered concurrent with a
typical 12 hour advance warning.
Total Clearance = Mobilization + Travel + Queuing Delay
Time Time Time Time
= 3 hours + .5 hours/1 + 2.72 hours/2
= 6.22 hours
Page 16

/1Travel Time: Under free flow traffic conditions, a car should
be able to travel from any point in the County south of Snow's
Cut to north of Snow's Cut within 30 minutes.
/2Queuing delay Time: Queuing delays will result from vehicles
coming from residential streets onto US 421 (Carolina Beach Road)
Calculations are given below:
-Assume that a total of 3635 households and motel room
groups will require evacuation. Each has an average of
1.6 vehicles per household, for a total of 5816 vehicles.
-Assume that one quarter (1454) of the vehicles will
evacuate from the area south of Carolina Beach north to
Carolina Beach, using the two-lane section of US 421.
Queuing Delay = 1454 vehicles
Time 1575 vph capacity
.92 hours
-Assume that all vehicles (5816) will evacuate north from
Carolina Beach to north of Snow's Cut, using the four lane
section of US 421.
Queuing Delay = 5816 vehicles
Time 3232 vph capacity
= 1.80 hours
-Total maximum queuing = .92 hours + 1.80 hours
delay time
= 2.72 hours
FIGURE EIGHT ISLAND
Total Evacuation = Total + Pre -Landfall
Time Clearance Hazard
Time Time
= 4.12 hours + 4 lours
= 8.12 hours
The total evacuation time of 6.12 hours indicates that Figure Eight Island
would be safely evacuated if evacuation is ordered concurrent with a 12 hour
Hurricane Warning.
Total Clearance = Mobilization + Travel/l Queuing Delay/2
Time Time Time Time
4.12 hours = 3 hours + .25 hours + .87 hours
Page 17

/1Travel Time: Under free flow traffic conditions, a car should
be able to travel fron either end of Figure Eight Island to the
mainlnd in 15 minutes.
/2Queuing Delay Time: Queuing delays will result frann vehicles
carving from residences onto Beach Road and then onto Bridge Road.
Calculations are given below:
-Assume that a total of 562 households require evacuation. Each
has an average of 1.6 vehicles per household, for a total of 900
vehicles.
Assume that one half of the vehicles (450) will evacuate
simultaneously from the northern end. For these two-lane
stretches of road, therefore, maximum queuing delay time
would be:
Queuing Delay = 450 vehicles
Time 1575 vph capacity
= .29 hours
-Assume that all vehicles must travel on the two-lane Bridge
Road to the mainland. This maximum queuing delay time would be:
Queuing Delay = 900 vehicles
Time 1575 vph capacity
= .58 hours
-Total Maximum Queuing = .29 hours + .58 hours
Delay Time
.87 hours
Page 18

V. ANALYSIS OF EVACUATION SHELTERS
According to the American Red Cross, contracts have been made between the
Red Cross and County schools to use the schools as needed for evacuation
shelters. Although the Red Cross in Wilmington has certain limited supplies
(cots, food, clothing) readily available, the Red Cross has established
agreements with local stores and Red Cross chapters elsewhere to obtain
additional emergency supplies as needed. The Red Cross also has established
provisions for emergency medical services and supplies. The Red Cross performs
these functions as part of their Federal mandate and in accordance with North
Carolina guidelines from the N. C. Department of Social Services. Principal
evacuation routes and shelters are shown in Figure 6 attached to the back of the
report.
The local government is responsible for providing utilities and water. The
National Guard is generally relied on for these services. In addition, the local
Civil Preparedness Office is responsible for coordinating the provision of
shelter, supplies, and services.
According to the Red Cross, the County schools have the capacity to shelter
17,000 persons. Assuming that only 20-35% of all evacuees (Stone, 1983) would
utilize the public shelter and that the rest would go to family, friends, motels,
or outside of the County, this capacity would greatly exceed anticipated use in
case of a hurricane.
VI. CONCLUSIONS AND RECOMMENDATIONS
The results, shown below, of this study indicate that the decision to
evacuate the beach areas should be made well ahead of the anticipated landfall of
the hurricane eye:
Clearance Time
Pre -landfall
Total
Area of
Mobilization
Travel
Queuing
Hazards
Evacuation
County
Time
Time
Delay Time
Time
Time
Wrig tsville
Beach
3 hrs.
.25 hrs.
3.36 hrs.
4 hrs.
10.61 hrs.
South of
Snows Cut
3 hrs.
.5 hrs.
2.72 hrs.
4 hrs.
10.22 hrs.
Figure 8
Island
3 hrs.
.25 hrs.
.87 hrs.
4 hrs.
8.12 hrs.
Mobilization time, essentially, is the time required for people to learn of
the evacuation decision and pack -up. Travel time is the time required to drive
from the beach. Queuing delay time is the additional time spent in traffic jams
or other delays. Pre -landfall hazards time is the time when hurricane conditions
arrive making evacuation unsafe before landfall of the hurricane eye.
It is important to note that these results are conservative on the safe
side. The study assumed "worst case" conditions, for instance, in assuming a
four hour pre -landfall hazards time. In addition, the study assumed that no one
would leave the beach before evacuation is ordered when, in reality, up to 30% of
the beach population would probably leave before the order is issued. If this
"early departure" value was factored in, queuing delay times would be reduced.
Page 19

The County's decision to evacuate presently is dependent upon the issuance
of a Hurricane Warning by the National Weather Service. Because the Hurricane
Warning generally is given at least 12 hours before anticipated landfall of the
hurricane eye, the calculated total evacuation times indicate the County's
present decision making framework is adequate for safe and timely evacuation.
This fortunate situation is primarily due to the presence of four -lane highways
along major sections of the evacuation routes that would be traveled to reach the
safety of the mainland. Shelters are also more than adequate.
It is important to note,, however, that total evacuation times for
Wrightsville Beach and for the area south of Snow's Cut may be approaching the
critical point where safe evacuation may become excessively difficult. This fact
emphasizes the need for maintenance of strict control procedures to minimize
mobilization and queuing delay times, e. g. not permitting sightseers to
cross over the bridges into the evacuation areas and controlling access at boat
ramps and marinas, and the need for development of a decision making structure
that can quickly order evacuation once the Hurricane Warning is issued, if not
before.
In addition, continued growth at Wrightsville Beach and the area south of
Snow's Cut, particularly Carolina Beach, could eventually result in queuing
delays that would make evacuation more difficult. The potential of such impacts
should be considered in the planning of future developments for these areas.
Page 20

REFERENCES
Carter, T. M., 1981, "Probability of Hurricane/Tropical Storm Conditions: A
User's Guide for Local Decision Makers," USDOC/NCA-NWS.
Collins, W. E., 1983, "Carrying Capacity Methodology", Nags Head, NC.
McElyea, W. D., D. J. Browers, and D. R. Godschalk, 1983, Before the Storm, Center
for Urban and Regional studies, UNC-Chapel hill.
Owens, D., 1981, "The Management of Oceanfront Development in North Carolina",
paper presented at the 7th Annual Conference of The Coastal Society, Oct. 11-14,
1981, Galveston, Texas.
Stone, J. R., 1983, "Hurricane Emergency Planning: Estimating Evacuation Times
for Non -Metropolitan Coastal Communities," Working Paper 83-2, Sea Grant Program,.
NCSU.
U. S. Corps of Engineers (US COE), 1982, "Feasibility Report and Environmental
Assessment on Shore and Hurricane Wave Protection", USCOE, Wilmington District.

0 1 2 2 _
Scale In Niles
LEGEND
ure Eight (stand
ghtsvilie Beach
rolina Beach
Wilmington Beach
Kure Beach
?gard High School
,and Grits Jr. High
PRINCIPAL. EVACUATION
ROUTES and SRE'.TERS
NEW HANOVER COUNTY, NC

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