CHAPTER 6: SECURITY FOR CENTRAL BUSINESS DISTRICTS

6.1	INTRODUCTION
F
or this publication, a central business district and downtown are terms referring to the commercial heart of a city. The events following the attacks in New York City on September 11, 2001, are recorded as among the worst building disasters in history and resulted in the largest loss of life from any single building collapse in the United States. 
Since the attacks of September 11, 2001, many security measures were installed in the central business district in New York City. In some cases these installations have been considered successful from a security, architectural, urban planning, and cultural preservation standpoint. In other cases, however, the installation of security barriers has had a detrimental effect. For example, the placement of physical barriers has caused unnecessary interruptions on streets and sidewalks. In many cases, it has minimized the efficiency of pedestrian and vehicle circulation systems, and potentially prevented the access of first responders in case of an emergency. If national security concerns continue, the need for barrier systems of various kinds may increase as our major cities continue to grow. However efficient pedestrian and vehicle circulation systems are also important for day-to-day living, and are critical for emergency response, evacuation, and egress.
This chapter focuses on providing security for typical central business district sites, in which space is limited and many of the measures applicable to open sites cannot be implemented.
6.2  	LAYERS OF DEFENSE AND URBAN SITE TYPES
Although the layers of defense for a central business district are very compressed, the general principles still apply. The layers may be narrow and some layers of defense may share the same space. As will be shown, in the zero setback site, the second layer of defense ceases to exist, while building yards and plazas form the second layer. Note that if the sidewalk provides the only defended stand-off, every foot of setback is value.

Three generic site types will be found in the central business district of 
any large city. These are:

*  Buildings with zero setback and alleys:  the front wall of the zero setback building face is on the property line.  An alley is a special case of a site with zero setback zoning in the form  of a narrow street that divides a city block and provides service access  to the buildings (Figure 6-1). 

*  Buildings with yards: the building is set back a small distance from its 
property line, and the space is usually landscaped. Yards may be on the 
front, sides, and rear of the building (Figure 6-2).

Figure 6-1:  Zero setback (left) and  alley (right). 

Figure 6-2:  The building yard. 

*  Building with plazas: The building is placed within a private or public 
open space that is publicly accessible (Figure 6-3).
In addition, all sites have a common set of urban elements: 
sidewalks, streets, and streetscape such as benches, planters, signs, etc.

Planning, design, and placement of security elements in the central 
business district should not be detrimental to the critical urban design 
components that contribute to the success of vibrant, livable cities:

*  A well-connected street system where the vehicle user and pedestrian 
have many choices to maneuver through a congested city to maintain 
traffic flow and pedestrian movement.

*  A well-defined pedestrian-scaled streetscape vocabulary that includes 
a consistent street wall and ample maneuverable areas for walking, 
waiting for public transit, and enjoying outdoor commercial activities 
such as eating, vending, window shopping, etc.

*  Publicly accessible ground-level commercial, cultural, or educational 
uses. If these uses cannot be accommodated within the building, 
then alternatives should be considered, such as outdoor vending or 
kiosks or types of visually appealing and interesting features along the 
ground floor of the building. 

*  Attractive and durable street furniture and utility infrastructure 
(signage, trees, benches, light poles, trash receptacles, security 
elements, etc.).

Figure 6-3: The plaza.

6.2.1 Zero Setback Buildings 

Due to the high cost of urban real estate, limited developable area and 
need to maximize use of space, most central business district buildings are 
commonly developed with exterior walls on the property line. In this type 
of site, the area between the property line and the building face, that in 
the open site provides the second layer of defense, does not exist. The 
sidewalk provides part of the first and second layers of defense. The third 
layer starts at the building face, which is also the property line. Often the 
sidewalk is a grey area, and barriers may be in the sidewalk or the building 
yard. If barriers are in the sidewalk, the city must review and give permission; 
if in the owner's property, no permission is necessary (Figure 6-4). 

When the property line is at the face of the building, the total space for 
perimeter barriers shrinks to a few feet of public sidewalk, and the street 
may be only a narrow alley primarily used for delivery. In these circumstances 
the strategies are limited and often challenging to employ due to 
space limitations and conflict with day to day use of the building and site. 
When planning barrier systems, the removal of curbside parking, or street 
closures, the following issues need to be considered:

Figure 6-4: Layers of defense for zero-setback building. 

*  Placing barriers within the sidewalk may cause long-term impairment 
of public mobility on sidewalks increased traffic congestion due to 
loss of traffic lanes and on-street parking, and may not be welcome 
or desirable. Limiting pedestrian movement in downtown districts 
and restricting access to stores, restaurants, offices and apartments 
can have a negative impact on the functionality of urban life and the 
viability of a city neighborhood. 

*  In many areas, street parking is often located within a desired stand-off 
zone. This parking is sometimes prohibited to increase the stand-off 
distance, but this practice should be avoided as much as possible 
(Figure 6-5).

*  Curbside parking should not be removed unless additional stand-off 
distance is absolutely necessary for high-risk buildings. High curbs 
and other measures may be installed to keep vehicles from departing 
the roadway in an effort to avoid security counter measures. When 
required, sidewalks can be widened to incorporate the area devoted to 
the curb lane. 
In some instances, prohibition of street parking or lane closure can 
be used as a temporary measure during times of increased alert. 
Temporary closure against enhanced threat should be carefully 
planned rather than improvised with ugly and disruptive measures 
(Figure 6-6).

Figure 6-5:  Permanent removal  of parking from the  curb lane of a major  building results  in a day-to-day  inconvenience.  
SOURCE: NCPC

In order to obtain adequate stand-off and restrict vehicular access in 
urban locations of very high risk, street closures and vehicular control 
and inspection can be considered. This solution should be carefully 
planned to establish its overall feasibility, based on its impact on the 
transportation infrastructure and possible disruption to local traffic patterns. 
A traffic study is necessary to provide more details of the impact 
of street closure and vehicular control and inspection on the local traffic 
pattern and neighborhood usage. 

When street closure is not feasible to provide adequate stand-off, a solution 
is to harden the building structure, glazing, and openings, and 
provide increased surveillance and security. Complete hardening of 
the structure and exterior envelope is realistic for a new building but 
very expensive for an existing one. Careful investigation may show 
that partial hardening, such as the lower floors of glazing and some 
strengthening of exposed perimeter columns, will reduce the risk to 
an acceptable level. Increased surveillance should also be provided to 
identify suspicious vehicles on adjacent streets, together with effective 
screening at public entrances and service areas. 

*  It may be desirable to regulate the type of traffic in urban areas to 
restrict the size of vehicles: for example, to prohibit truck traffic 
in certain zones to reduce the risk of a particular magnitude of 
explosion.
In a central business district in which the threat to an individual 
building is relatively low, the building is well constructed, and the possibility 
of a head-on high-velocity vehicle attack is minimal, acceptance of 

Figure 6-6: Improvised street closure and control.

risk may be the most reasonable course of action. Many older buildings 
(late 19th and early 20th centuries) are strong structures consisting of 
a steel frame encased in masonry or concrete, with small window openings 
and masonry walls. Earlier buildings may have load-bearing walls 
with massive lower floor walls. They may withstand considerable impact, 
but if once breached, progressive collapse may be more likely than for 
steel or reinforced concrete framing.

In summary, the central business district requires a compromise solution 
that involves some or all of the following measures: 

*  Provide a barrier at the sidewalk edge to obtain a few more feet of 
stand-off and prevent vehicles mounting the sidewalk.

*  Remove critical functions from the lower floors. 

*  Strengthen glazing and frames.

*  Harden loading docks and garage areas.

*  Use intensive surveillance by cameras and security personnel. 
Sidewalks are often only about 10 feet wide and as little as 6 feet in alleys, 
making it impossible to establish adequate stand-off distance. For 
high-threat sites, a perimeter barrier at the edge of the sidewalk (but allowing 
space for car doors to open) both protects pedestrians from close 
traffic and prevents potential attackers from mounting the sidewalk.

Figure 6-7 shows a building that has a 7-foot-wide sidewalk facing a 
narrow street that is, nevertheless, an important roadway that must be 
maintained; the protection shown is temporary. The building defense 
relies on preliminary screening at the sidewalk behind temporary metal 
barriers, followed by full control and search within the building entrance. 
Jersey barriers are placed at curbside to protect pedestrians from 
traffic and prevent a passing attacking vehicle from mounting the curb 
and evading pursuit.

Use of Jersey barriers as shown in Figure 6-7 above is undesirable, because 
they are not an effective barrier, are unattractive in appearance and may 
interfere with car door opening. This is a temporary version of the more 
satisfactory engineered bollard layout shown in Figure 6-8. In this instance, 
the sidewalk serves as the second layer of defense. Well-designed engineered 
bollards inset from the sidewalk edge, and interspersed with trees, 
allow for car door opening, prevent an attacker from mounting the sidewalk, 
and provide the everyday advantage of protecting pedestrians from 
normal traffic on a busy street. Temporary metal barriers are used between 
curb and building when a screened entrance is in use, and the engineered 
barriers at the sidewalk delineate the transition to the first defense layer. 

Figure 6-7: 
Unsatisfactory example of temporary protection for a high-risk zero-setback building. If the Jersey barriers 
are not embedded, they can be pushed aside by a vehicle.

 Figure 6-8:  A well-designed zero- setback protection. The  engineered bollards  define the transition  between the first  and second layers  of defense and the  street trees soften the  intrusion of bollards. 

6.2.2 Alleys

The most extreme forms of the zero-setback building are found in alleys: 
a typical alley roadway has a width of about 20 feet, with a sidewalk perhaps 
as little as 6 feet wide. Sometimes there is a sidewalk on only one side 
of the alley (Figure 6-9).

Figure 6-9: Alleys. Note single sidewalk (right).

The protective measures described above for zero-setback buildings apply 
to buildings serviced by alleys.

In alleys and typical urban streets, adequate stand-off distance is often an 
impossibility without street closure, but permanent closure is often not 
feasible because of service entry needs. In this instance, street closure that 
also allows service access can be achieved by use of active barriers, such as 
retractable bollards or other devices, together with security personnel and 
well-planned screening and inspection facilities.

Well-planned and well-designed street closures can enhance the quality 
of a street, even in a high-risk area. It is critical that a permanent street 
closure be planned, not only as part of an organized traffic study that respects 
existing traffic patterns, but also tries to find an opportunity to 
improve them and enhance the neighborhood. Control of vehicular 
speed is also important for security. This is discussed in Section 5.4 but 
some of the methods noted in that section (such as traffic circles) may not 
apply in the urban environment because of lack of space.

Security measures can be both effective and attractive if design attention 
is focused on the required performance, and imagination is used in materials 
and forms. Good design requires site-specific, context sensitive 
solutions. The function of the public realm and the site's context must be 
carefully considered when designing and placing hardened streetscape elements, 
and placement of these elements must be carefully evaluated to 
avoid visually and physically cluttering the streetscape. Solutions should 
not be universally applied. In some cases, in important historic areas of 
cities or in relation to important historic buildings, security elements in 
public space should be discouraged altogether.

Case Study 6 provides an example of a well-researched neighborhood 
protection plan that uses street closure to provide stand-off and also enhances 
the urban values, vitality, and function of the protected area. 

CASE STUDY 6: NEW YORK CITY FINANCIAL DISTRICT 

1.0 INTRODUCTION

1.1 Project Scope

After 9/11, the New York City Financial District was identified as a likely target for terrorism. 
The City of New York and the New York Stock Exchange (NYSE) took immediate steps to secure 
the perimeter of the financial district. The city's public spaces suffer from heavy-handed, quick-fix 
installations of cumbersome security devices that mar the experience of the public realm. 

The financial district is a close irregular pattern of  streets heavily traveled by automobiles, service  vehicles, and pedestrians; to create sufficient  stand-off for the NYSE would entail closing a  number of streets. This was initially accomplished  by a vast array of jersey barriers, barricades,  and stationary pick-up trucks to block incoming  traffic, together with increased security personnel  and manned check points that had a negative  effect on the quality of the city's public spaces.  Rogers Marvel Architects led a multidisciplinary  team that included Quennell Rothschild Partners  (landscape), Weidlinger Associates (force protection), Ducibella Ventor and Santore (security) ands  Philip Habib Associates (traffic). In addition, a number of public agencies were involved, including  the NYC Department of City Planning, the Lower Manhattan Development Corporation, the NYC  Economic Development Corporation, the NY Stock Exchange (NYSE), the NY Police Department  (NYPD), and the NYC Department of Transportation. The plan recognizes that the real problem  is not security itself, but how to prevent the threat of attack from destroying the urban fabric,  preserving a psychology of openness, and treating security as an amenity within the public realm.  

2.1 Issues Addressed

The basis of the Rogers Marvel team's approach was to build only amenities. Security was seen as 
an urban design problem, involving the use of security dollars to create or enhance public space. 
That way, the finished project would benefit the community, whether or not the security features 
were ever put to the test. 

The security infrastructure is programmed for civic functionality as well as protection. This entailed 
four strategies:

*  Rethinking the way the financial district works in terms of circulation and security
*  Changing the traffic pattern and lessening the impact of security measures
*  Dispersing the necessary protection element among streetscape elements
*  Because of the density of the urban space, making every inch count

2.2 Security Strategy

First Layer of Defense

*  Perimeter barriers consisting of bollards and  specially designed sculptured forms used to  provide street closures. The sculptured forms, or  "NOGOs," need only a shallow foundation and  add an interactive element to the streetscape.   
*  Controlled access was maintained by rotating  road barriers, turntables, and other operable  barriers. 
*  Judicious street closures, with  controlled access, in order to  provide adequate stand-off from  possible target assets.    
*  Closures carefully planned to  enhance pedestrian experience  and create well-used pedestrian  plazas. 

Third Layer of Defense

Many of the key buildings in the district are older buildings 
well constructed in a monumental style. Individual owners 
have pursued appropriate defense measures depending on 
the nature and location of their assets.

2.3 Blending with the Neighborhood Context

This project uses a family of specially designed streetscape elements that reinforce the identity of the 
financial district and the NYSE area. In addition, the project addresses this generation's threats with 
proposals that connect the programmatic needs of the contemporary streetscape with the original 
canal and security perimeter of New Amsterdam.

Road beds are remade using walkable cobble stones as a surface, further defining the 
"pedestrian space." Lighting and open spaces are added to create a sense of community within 
the financial district. 

3.0 INNOVATIONS AND BEST PRACTICES

This project was largely responsible for the development of a number of streetscape items. It 
successfully illustrates ways to treat security as an amenity instead of a burden.

The security design established a vehicle-free pedestrian plaza on Broad Street and added pedestrian-
oriented street lighting throughout the district. The financial district is no longer a workday community 
emptying after the trading floor closes. Through rezoning and redevelopment, the character of the 
district is changing to a 24-hour community with restaurants, schools, retail, and resident families.

In addition, reinforced glass street furniture and specialized street lighting have been developed.

Wall Street and Broadway before (left) and after (right).

6.3 BUILDING YARDS

Some buildings have a "yard" between the building face and the 
sidewalk. The yard is within the property line and typically consists 
of a grassy or planted area adjacent to the building. Yards are 
usually provided for governmental or institutional buildings in which coverage 
of the entire property may not be as economically critical as it is in 
private development. Yards are typically narrow, on the order of 10 to 20 
feet, providing some stand-off distance beyond the sidewalk. 

Although compressed, the three layers of defense can be identified in the 
building with a narrow yard shown in figures 6-10 (plan) and 6-11 (section). 
The curb lane and the sidewalk together form the first layer of 
defense. The sidewalk serves as the common space for pedestrian movement, 
activity, and interaction. The building yard is the second layer 
of defense. In the yard, security components should complement the 
building architecture and the landscaping, because they will be easily visible 
from the sidewalk, and should be located near the outer edge of the 
yard. An engineered planter or plinth wall can provide a good security 
barrier for this layer. The third layer of defense is at the face and interior 
of the building.

A flush or low planter provides little or no protection from vehicles, but 
an engineered planter or high retaining wall and planter can be an effective 
barrier (Figure 6-13).

Figure 6-13: 
A typical raised low planter (left) may be too low to present a significant barrier to vehicles. The high 
stepped yard (right), which runs along the side of the building, is a significant barrier and could also act 
as a blast deflector from a curbside vehicle.

Figure 6-12: 
Narrow yard with a raised planter (left); narrow yard and low planter with a wide sidewalk (right).

Security elements within the building yard should complement the 
building architecture and landscaping, and should be designed to appear 
as well-designed landscape objects rather than as security measures 
(Figure 6-14).

6.4 PLAZAS

When extensive business district development with very large 
buildings began after World War II, and the straight tower 
with no setbacks became fashionable, new ordinances permitted 
building developers to construct taller buildings, with greater floor 
area, if a public plaza were incorporated (Figure 6-15).

In essence, the plaza is an extended building yard that was moved outside 
the controlled access to the building and became public space provided 
by the developer. 

Plaza layers of defense are similar in arrangement to those of the yard. 
The additional space provided by plazas enables a more effective second 
layer of defense to be achieved in an urban setting, and often an acceptable 
stand-off distance can be created on one or more faces of the 
building, depending on the plaza-building relationship. Figure 6-16 shows 
the layers of defense with a plaza.

Figure 6-14: 
Barriers in harmony with the architecture. The seating (left) and the serpentine wall (right) are engineered 
barriers.
SOURCE: NCPC

Public buildings are frequently located within large plazas that are carefully 
designed to provide pleasant spaces for people to relax, converse, 
and enjoy the outdoors in a more spacious urban setting.

The plazas also provide an opportunity to install barriers within the 
second line of defense -- the plaza itself. Designers are now experimenting 
with the use of interesting forms intended to enhance the experience of 
the plaza while improving security (Figure 6-17). 

Figure 6-15:  Major office building  situated on a public  plaza.   

Figure 6-16:  Layers of defense for a  plaza.    

The plaza in Minneapolis shown below is located between the City Hall 
and a new federal courthouse. The entire plaza is built on a parking garage 
roof. The design refers to Minnesota's cultural and natural history; 
earth mounds and logs, elements of that history, are the plaza's symbolic 
and sculptural elements. An earth mound is also almost impossible to 
drive over, but if anyone manages to surmount it, the mound will collapse 
into a void below. The huge logs also limit the possibility of direct vehicular 
access to the building (Figures 6-20 through 6-23).

Figure 6-19: Steep flight of steps and water feature acting as barriers. 
SOURCE: PETER WALKER AND PARTNERS

Figure 6-20:  Minneapolis  courthouse plaza  on a garage roof  with planted berms  and log benches  that symbolize  Minnesota's history.  SOURCE: COURTESY OF  MARTHA SCHWARTZ, INC.     

Figure 6-21:  Minneapolis  Courthouse plaza  with planted berms,  representing historic  Minnesota "drumlins."  They also act as  barriers to a vehicular  attack, as a second  layer of defense,  creating stand-off.  SOURCE: COURTESY OF  MARTHA SCHWARTZ, INC.   

Figure 6-22:  Minneapolis  Courthouse plaza:  detail of drumlin and  logs. The logs serve as  seating.  SOURCE: COURTESY OF  MARTHA SCHWARTZ, INC.    

6.5 ACCESS POINTS

Security may prevent normal through-site access. Vehicles may be 
used to carry explosives and CBR material near or into a facility. A 
terrorist vehicle bomb driven near or into the building, or a hand-
carried bomb placed close to the building, can severely injure people and 
damage structures. In case a barrier or control booth is necessary, they 
need to be carefully designed to reduce their visual impact. Too many entrances 
can stretch security forces thin and/or increase the expense of 
security force and equipment cost in controlling access. 

For high-risk facilities and heightened threat levels, it is important to 
screen visitors and/or staff for weapons and explosives. Screening may include 
visual inspection, baggage search, walk through, hand-held metal 
detectors, x-ray inspection machines, explosives detectors, and chemical 
and biological agent detectors. If screening equipment is required, appropriate 
space should be allocated early in the design or retrofit planning 
phases. This space should be carefully designed according to the type of 
security required, the anticipated number of visitors, and the number of 
security personnel. Large accumulations of people at the entrance of a 
building should be avoided, since crowded conditions can conceal covert 
activity, such as the placement of a hand-carried bomb. 

An adequate number of security personnel and sufficient inspection 
equipment should be provided to facilitate rapid processing of visitors 
and staff, especially at the opening of business, lunchtime, and close of 
business. Long queues can result in a tendency to hurry the screening 
process, which might provide an opportunity for unauthorized access for 
people and weapons. If there is sufficient space inside the entrance of the 
building, queuing will occur within the building footprint. If there is insufficient 
space inside the entrance, queuing should be expected outside 
the building, and a rain cover should be provided.

Figure 6-23:  Drumlin direction and  plaza paving pattern  lead pedestrians  towards building  entrance.  SOURCE: COURTESY OF MARTHA SCHWARTZ, INC.

Figure 6-24 shows a well-designed vehicle entrance. This combines a 
simple gatehouse and building sign with a graceful arched protective 
roof. 

6.6 INTERMODAL SYSTEMS

Typically, urban sites with access to nearby transit, bus lines, rail, 
and other modes of transportation should be carefully evaluated 
for security and circulation impacts. Staff and visitors require 
convenient access to the stations and stops, which may conflict with 
stand-off and site access needs. The design of walkways, bus stops, drop 
off zones, and parking areas should balance functionality with security 
requirements of the project for stand-off distance, accessibility control, 
screening, and control of views. In some instances, subway stations can 
be entered directly from a building or the street entry leads both to the 
building and a subway station. Inter modal hubs are shown in Figures 6-25 
and 6-26.

Figure 6-24:  Pedestrian entry has  new gates designed  in keeping with the  historic fence (top).  A graceful arched  canopy and elegant  guard house provide  vehicular entry control  
SOURCE: NCPC

Some considerations for minimizing the impact of security measures in 
the vicinity of intermodal hubs are:

*  Exploring ways to mitigate impacts of security improvements that 
restrict access to or use of subways and railroads by regular users.
 Figure 6-25:  Large intermodal hub  with parking, main  railroad, subway, and  buses.  
SOURCE: GOOGLE EARTH,  MODIFIED   

Figure 6-26:  Urban intermodal  hub. aerial view, left.  An entry that serves  both as a subway  and building access is  shown, right.   
SOURCE: GOOGLE EARTH,  MODIFIED, left.    

*  Studying locations for security improvements and alternatives for 
circulation paths that mitigate impacts on existing circulation routes 
to stations, bus stops, etc. 

*  Designing for the appropriate level of security based on the design 
basis threats, and increasing controls by planned temporary means if 
the threat level increases.

*  Understanding the community impact of developing perimeter 
security and devising potential mitigation strategies to preserve local 
mobility and connectivity. 

*  The need for special protective measures at bus stops and other drop-
off and pick-up areas (Figure 6-27).

6.7 PARKING

6.7.1 Introduction

Typical parking in the central business district includes public on-
street parking lanes, underground parking beneath plazas or other 
public spaces, parking beneath buildings, and freestanding or 
attached parking structures.

Surface parking lots are often congested and temporary, awaiting development. 
Mitigating the risks associated with parking requires selection of a 
coherent set of design measures, including parking restrictions, perimeter 
buffer zones, barriers, structural hardening, and other architectural and 
engineering solutions (Figure 6-28).

Figure 6-27: Bus stops and other drop-off and pick-up areas may need special protective measures.

 Considerations for public street parking include:

*  Request appropriate permits to restrict parking in curb lanes in 
densely populated areas to company-owned vehicles or key employee 
vehicles.

*  The impact on local businesses due to loss of on- street parking should 
be evaluated.

*  Provide appropriate setback from parking on adjacent properties, if 
possible. Structural hardening and/or enhanced surveillance methods 
may be required if the setback is insufficient. In new designs, it may 
be possible to adjust the location of the building on the site to provide 
adequate setback from adjacent properties.

*  Pick-up and drop-off areas should have appropriate barriers at 
the edge of the curb to enforce stand-off distances for unscreened 
vehicles and to address mobility and convenience for pedestrians. 
This includes placement of barriers at a distance from the curb to 
allow clearance for vehicle doors to open, provision of adequate 
lighting and shelter so pedestrians can wait safely for their rides, and 
appropriate design for handicapped access. Circulation planning 
should make sure that effective access is available for first responders 
and other emergency vehicles (Figure 6-29).

Figure 6-29: Lengthy shelter for curb lane drop-off and pick-up area.
SOURCE: NYPD

The following sections offer security design guidance for the layout and 
design of public on-street parking lanes, underground parking, and 
parking within buildings.

6.7.3 Underground Parking and Parking 
beneath Buildings

Buildings adjacent to underground parking may suffer collateral damage 
in the event of an explosion within the garage. This risk must be evaluated 
to determine the level of inspection and control at the entry. 
Typically, this would be limited to fee taking and cursory inspection, but 
for a high-risk building or a heightened condition of security, careful security 
inspection may be necessary on a temporary basis. 

Protection of primary vertical load-carrying members by designing architectural 
or structural features that can keep an explosive even a few feet 
away can make a big difference. For portable devices, a few inches or a 
couple of feet may be critical. Emplacing sloped features or other simple 
designs around accessible portions of columns are simple measures that 
may prevent a column collapse, and parking design may also be used to 
keep vehicles a few feet away from columns. These are simple, cost-effective 
measures that can minimize risk of collapse and still be unobtrusive 
or even attractive.

Typical entry control to protect underground parking beneath high-risk 
buildings is shown in Figures 6-30 and 6-31.

Figure 6-30: Entry control to underground garage. Note provision for queuing and gatehouse design in harmony with the building. Careful design of all the needed components is necessary to avoid clutter. If possible, such entry control is best located on an access road or service alley rather than a public street

If parking beneath a high-risk building must be provided, access to the 
parking area should be controlled and limited, and spaces should be well-
lighted and free of places of concealment and dead-end parking spaces. 
The following restrictions may need to be applied:

*  Public parking with ID check.

*  Company vehicles and employees of the building only.

*  Selected company employees only, or those requiring security.
The designers needs to consider the following:

*  For all stand-alone, above-ground parking garages, maximize visibility 
for surveillance into, out of, and across the garage.

*  Employ express or non-parking ramps, sending the user to parking on 
flat surfaces. 

*  Stairways and elevator lobby design should be as open as code 
permits. The ideal solution is a stair and/or elevator waiting area 
totally open to the exterior and/or the parking areas. Designs that 
ensure that people using these areas can be easily seen (and can 
see out) should be encouraged. If a stair must be enclosed for code 
or weather protection purposes, glass walls can be used to deter 
potential attacks. Potential hiding places below stairs and within and 
around stairwells should be closed off.

Figure 6-31:  View from a public  street of entry control  for underground  parking at a court  house. The entry is  used for prisoner  delivery and limited  parking controls.  Elimination of  temporary signs and  posts might reduce the  clutter.   

*  Elevator cabs should have glass backs whenever possible. Elevator 
lobbies should be well-lighted and visible to both patrons in the 
parking areas and the people outside the building.

*  Pedestrian paths should be designed to concentrate activity to the 
extent possible. For example, bringing all pedestrians through one 
portal rather than allowing them to disperse to numerous access 
points improves their ability to see and be seen by other users. 
Limiting vehicular entry/exits to a minimum number of locations is 
also beneficial. 

*  Parking structures open to the public should be sited and evaluated 
with concern for stand-off from other buildings and screening from 
critical operations and sensitive areas that might be observed from 
within the parking structure and used as a point of access or staging 
for use of weapons or explosives. 

*  Urban parking structures are likely to have high volumes of 
pedestrians and vehicles to accommodate, may be connected by 
bridges to nearby building, and may provide high vista points for 
surveillance or threat to adjacent buildings. 

*  In the design of parking structures that include screening or 
inspection, consider locating these functions outside, at adequate 
stand-off distances, to control impact from explosions. Adequate space 
should be provided for queuing and inspection, so as not to slow 
traffic in and out of the garage (Figure 6-32).

Figure 6-32:  Queuing and  inspection outside  an entry to parking  beneath a building.  

Design considerations for loading docks and service access include the 
following:

*  Separate (by at least 50 feet) loading docks and shipping and receiving 
areas in any direction from utility rooms, utility mains, and service 
entrances, including electrical, telephone/data, fire detection/alarm 
systems, fire suppression water mains, cooling and heating mains, etc.

*  If possible, avoid having driveways within or under buildings. If 
necessary, monitor them and restrict height to keep out large vehicles.

*  Significant structural damage to the walls and ceiling of the loading 
dock may be tolerable, as long as the areas adjacent to the loading 
dock do not experience severe structural damage or collapse. This can 
be achieved by an adequate structural design that limits damage to the 
loading dock area and allows explosive forces to vent to the building 
exterior. The floor of the loading dock does not need to be designed 
for blast resistance if the area below is not occupied and/or does not 
contain critical utilities.

*  Provide signage to clearly mark separate entrances for deliveries. 

*  The loading zone should be designed for effective observation by 
cameras or guards. The design of planting areas, walls, and steps, 
and the selection of plants and street furniture should allow easy 
observation of the space and avoid areas where packages might be 
hidden. 

Figure 6-33:  Screening areas  need sufficient space.  This loading area is  immediately adjacent  to a public sidewalk.  When two or more  vehicles are stopped,  pedestrian activities  can be disrupted, and  risk to passersby is  increased. 
SOURCE: FEMA E155 

6.9 PHYSICAL SECURITY LIGHTING

Adequate lighting should be provided to aid in threat detection; 
this also assists in providing a defensible space for pedestrians. 
Site lighting is an integral component of the site design, with 
several functions (Figure 6-34):

*  To extend the hours of use into the early morning and evening by 
illuminating entries, walkways, signage, and roadways. 

*  To improve security and provide enhanced visibility.

*  To add beauty by illuminating architectural details, landscape areas, 
specimen plants, outdoor artwork, and other features.

Figure 6-34: Appropriate lighting for a variety of situations.
SOURCE: DEPARTMENT OF STATE

A successful site design will consider appropriate types and light levels for:

*  Emergency lighting as part of emergency backup systems (Refer to 
FEMA 426, Section 2.9, for more information about these four types of 
site lighting).

*  Entry points (e.g., site entry points and building ingress and egress).

*  Circulation (e.g., roadways, parking areas, sidewalks, and walkways). 

*  Street and perimeter lighting.

*  Signage illumination.

*  Decorative landscape lighting.

*  Security lighting.

Site lighting can be separated into zones in order to concentrate light 
where it is needed most. Prioritizing will allow for the most efficient 
use of lighting, while keeping within a reasonable budget. Figure 6-35 
shows some typical zones; the numbers on the figures refer to the descriptions 
below.

1. Exterior surface of building, including walls, doors, windows, rooftop 
terraces, and balconies.

2. Outdoor areas directly associated with entryways to building, including 
walkways, steps, ramps, terraces, and loading docks.

3. Intermediate outdoor areas, including driveways and parking; 
walkways and paved terraces; small gardens and large, remote 
landscaped areas; recreational facilities; and utility, service, and 
storage areas.

4. Areas immediately inside the perimeter, including inside faces of walls 
and required clearances; pedestrian entryways, vehicular entryways, 
and security check points.

5. Areas outside the perimeter that may be considered defensible space, 
including public sidewalks and streets, waterways, and adjacent non-
public properties.

It is also important to consider operational costs when designing an appropriate 
lighting situation.

*  Estimate and evaluate the lifecycle costs for energy and maintenance. 

*  Evaluate the impact on project sustainability.
In addition, site lighting can be helpful as a response to different levels 
of alert, by designing it to be increased in times of high security alert. 
Provision of additional light is a common CPTED technique to discourage 
unwanted activities on sites and within buildings and to enhance desirable 
activities (Figure 6-36).

Figures 6-35: Site lighting zones.
SOURCE: DEPARTMENT OF STATE

6.10 INFRASTRUCTURE AND SITE UTILITIES 

In-ground infrastructure can be any of the following:

*  Standard utility lifelines such as water, gas, steam, sewer, storm water, 
electric communications, etc.

*  Any structure that can be used by persons, such as subway tunnels, 
stations, large sewer or water tunnels, or pipes.

*  Ventilation shafts supplying either the building or the in-ground 
infrastructure.
In the urban situation, it may be necessary, because of the limited space, 
to place vehicle barriers on yards, sidewalks, or plazas that are located 
over a dense infrastructure of all kinds of utilities, some of which may 
have been in existence for decades. There may be conflicts below grade, 
as an increasing number of current and past utility systems compete for 
limited space. Determination of the materials, size, and location, both 
horizontal and vertical, of these utilities is critical, because their interaction 
with barrier foundations may create costly or even impractical 
conditions; the location of barriers may be strongly influenced by the 
utility pattern. In addition, subway stations, public parking structures, 
and utility tunnels may have direct access to areas adjacent to building 
utility systems.

Figure 6-36: Night view of government building approach and screening structure.

Unlike an open site, in-ground utilities connect to the building directly 
from the municipal services. Thus the primary concern of the property 
owner is that of the security of this connection and any necessary openings 
into the building.

Failure of part of the in-ground infrastructure may affect the structural 
system of the building. When the infrastructure and the building are in 
close proximity or rigidly linked, the failure of one system may initiate 
failure of the other. The part of the structure closest to the in-ground infrastructure 
is the most vulnerable. It should be hardened so that any 
local failure would not initiate progressive collapse in the rest of the 
building. Aside from hardening, other measures available are increased 
ductility, increased setback, or better access control.

In a zero setback situation in-ground utility systems and other lifelines will 
be under public property and not under the building owner's control. 
Coordination with the public agencies will be necessary to ensure protection 
to the systems so that the building functions will not be affected by 
damage to the municipal utilities and infrastructure. 

In the case of a building located on a large plaza, critical utilities my be located 
on the owner's property. and their protective design may be part of 
the project scope. Some issues related to urban site utilities and infrastructure 
are:

*  Based upon the size of the lifeline, such as a large sewer system, access 
to the site or building may be possible and, based on the size of the 
utility service entrance to the building, personnel or CBR agents may 
be able to enter the building. 

*  In-ground infrastructure and the building can be connected by 
passageways, subways, tunnels, connecting stairways, entrance/exit 
portals, and ventilation shafts, as well as by direct utility connections 
from utility lifelines. 

*  Lifeline attachment to a building should be sealed to prevent 
infiltration of CBR and large entrances secured to prevent personnel 
access. 

*  Redundant sources of supply and any on-site storage needs, e.g., water 
storage (for domestic and industrial use or fire suppression), fuel 
storage, and on-site generators, should be identified. Each utility system's 
requirements for siting, redundancy, and safety should be addressed.

*  Plans for installation and modification of utilities for security purposes 
should be coordinated with local municipalities and/or service suppliers. 

Utility systems can suffer significant damage when subjected to the shock 
of an explosion. Some of these utilities may be critical for safely evacuating 
people from the building. Their destruction could cause damage 
that is disproportionate to other building damage resulting from an explosion. 
To minimize the possibility of such hazards, apply the following 
measures, where appropriate:

*  Ensure that access to crawl spaces, utility tunnels, and other means 
of under building access is controlled in order to limit opportunities 
for aggressors to place explosives underneath buildings. All utility 
penetrations of a site's perimeter barrier should be sealed or secured 
to eliminate openings large enough for persons to pass through 
the barrier. Typical penetrations could be for storm sewers, water, 
electricity, or other site utility services.

*  If access is required for maintenance of utilities, all penetrations 
should be secured with screening, grating, latticework, or other 
similar devices so that openings do not allow intruder access. Provide 
intrusion detection sensors, and consider overt or covert visual 
surveillance systems, if warranted by the sensitivity of assets requiring 
protection.

*  Protect vents, ducts, and other openings that pass through a 
perimeter and that have a cross-sectional area greater than 96 square 
inches, and whose smallest dimension is greater than 6 inches, by 
securely fastened welded bar grilles. 

*  Consider quick connects for portable utility backup systems if 
redundant sources are not available.

*  Prepare vulnerability assessments for all utility services to the site, 
including all utility lines, storm sewers, gas transmission lines, 
electricity transmission lines, and other utilities that may cross the site 
perimeter. 

*  Provide utility systems that support site security, life safety, and rescue 
functions with redundant or loop service, particularly in the case 
of electrical systems. Where more than one source or service is not 
currently available, provisions should be made for future connections. 

*  The choice of cover materials in sidewalks and other pedestrian areas 
should enable ease of access to utilities for repair and maintenance, 
but limit access by terrorists or vandals. Attractive paving that is easily 
removed and replaced can be substituted for standard concrete 
sidewalks that have to be torn up and patched (Figure 6-41).

6.11 CONCLUSION

Protection of sites in an urban environment presents particular 
difficulties; desired stand-off is unobtainable, road patterns are 
fixed, and road closures can be extremely disruptive. It may be 
necessary to accept a higher level of risk. This may be partially offset by 
the facts of urban congestion that may block the terrorist from making a 
high speed head-on attack on a building. 

The possibility of an attacker parking, even briefly, adjacent to a target 
building, however, is an ever-present threat. This underscores the need 
for protective measures applied to the building exterior and possible reprogramming 
to remove critical assets from the lower floors adjacent 
to the street. A common offset, however, is that many downtown buildings, 
particularly those constructed before World War II, are very solidly 
built, with concrete-encased steel frames, short structural spans, and small 
window openings. These types of buildings have been found to be very resistant 
to collapse.

The protective measures applied to the New York City Financial District, 
described in Case Study 6, show that a coherent and imaginative approach 
to the problem can achieve urban enhancement, even when street 
closings are necessary to achieve acceptable stand-off from high-risk targets. 
The exciting quality of the environment is maintained, new public 
space is created, and the rich history of the location is reflected in the nature 
and placement of contemporary protective installations. 

Figure 6-37: Sidewalk paving with removable panels eases maintenance of underground utilities.