12
HAZARD TO LIFE
Introduction
12.1
Background
12.1.1
ERM-Hong Kong Ltd (ERM) has been commissioned
to conduct a Hazard to Life Assessment (HA) for the In-Situ Reprovisioning of
Sha Tin Water Treatment Works (Sha Tin WTW) South Works Project (hereinafter
referred to as “the Project”). The hazard assessment is a part of the
Environmental Impact Assessment for the Project conducted under the EIAO. The
EIA Study Brief is registered as "In-situ Reprovisioning of Sha Tin Water
Treatment Works – South Works” (Reference No. ESB-220/2011) and was issued on 9
March 2011.
12.1.1
Requirements for assessment of hazards to
life are presented in Section 3.4.3 of the Study Brief. Section 3.4.3.2
stipulates that:
The Applicant shall investigate alternative construction methods to
avoid the use of explosives. If there is use of explosives for the construction
activities and the storage or blasting location is in close proximity to
populated areas and/or Potentially Hazardous Installation site (i.e. STWTW),
the Applicant shall carry out hazard assessment as follows:
(i) Identify hazardous scenarios associated with the transport, storage
and use of explosives (including possible damage scenarios to gas and chlorine
facilities) and then determine a set of relevant scenarios to be included in a
Quantitative Risk Assessment (QRA);
(ii) Execute a QRA of the set of hazardous scenarios determined in (i),
expressing population risks in both individual and societal terms;
(iii) Compare individual and societal risks with the criteria for
evaluating hazard to life stipulated in Annex 4 of the TM; and
(iv) Identify and assess practicable and cost-effective risk mitigation
measures.
The methodology to be used in the hazard assessment should be consistent
with previous studies having similar issues (e.g. Shatin-to-Central Link (Tai
Wai to Hung Hom Section) (ESB-191/2008), and Central Kowloon Route
(ESB-156/2006).
12.1.2
Section 3.4.3.3 of the Study Brief stipulates
that:
The Applicant shall investigate methods to
avoid and/or minimize chlorine risks. The Applicant shall carry out hazard
assessment to evaluate potential hazard to life during construction and
operation stages of the Project due to STWTW. The hazard assessment shall
include the following:
(i) Identify hazardous scenarios
associated with the transport, storage and use of chlorine at STWTW (including
possible damage scenarios associated with construction activities, storage of
liquid oxygen) and then determine a set of relevant scenarios to be included in
a QRA;
(ii) Execute a QRA of the set of hazardous
scenarios determined in (i), expressing population risks in both individual and
societal terms;
(iii) Compare individual and societal
risks with the criteria for evaluating hazard to life stipulated in Annex 4 of
the TM; and
(iv) Identify and assess practicable and
cost-effective risk mitigation measures.
The methodology to be used in the hazard
assessment should be consistent with previous studies having similar issues
(e.g. Shatin-to-Central Link (Tai Wai to Hung Hom Section) (ESB-191/2008), and
Integration of Siu Ho Wan and Silver Mine Bay Water Treatment Works
(ESB-150/2006)).
12.1.3
The scope section of the Study Brief also
states (Section 3.2.2 (vi)):
Potential hazard to life on construction
workers, operational staff and other sensitive receivers to be identified, with
STWTW is Potentially Hazardous Installations (PHI) due to the use of liquid
chlorine on site and the Beacon Hill North Offtake Station and its associated
750mm diameter high pressure gas pipeline that runs through the old Beacon Hill
Tunnel, and the possible use of explosives for blasting if applicable.
12.1.4
As required by the Study Brief, this
assessment concerns hazards related to transport, storage and use of chlorine
at Sha Tin WTW (STWTW) during the Construction Phase (South Works reprovisioning
works) and Operational Phase of the Project (after the project completion). The
approach adopted follows that of previous studies having similar issues.
12.1.5
Hazards relating to liquid oxygen are not
included in the assessment as it has been confirmed that there will be no
storage of liquid oxygen at Sha Tin WTW. Also, there will be no use of
explosives and hence this is not considered further in the assessment. Further,
it has been confirmed by HKCG that there are no high pressure gas pipelines
running through the old Beacon Hill Tunnel.
12.1.6
Additional hazard to life requirements are
also formulated in Section 2.1 (v) of the Study Brief, which as one of the
objectives of the EIA Study specifies:
To identify and assess the potential risk to
human life due to the construction works impact on the operation of the
existing PHI (Chlorine Store), the 400kV overhead power line and other notifiable gas installations
(NGIs), e.g. Beacon Hill North Offtake Station present or in the vicinity of
Project site and to propose measures to
mitigate these impacts.
These
issues are also addressed in relevant sections of this assessment.
12.2
Hong
Kong Risk Guidelines and Other Relevant Legislation
12.2.1
Hong Kong Risk Guidelines (HKRG) for
Designated Projects are defined in Annex
4 of the Technical Memorandum to
Environmental Impact Assessment Process (EIAO-TM) in terms of individual
and societal risks as follows:
·
Maximum level of off-site individual risk
should not exceed 1 in 100000 per year, i.e. 1 × 10-5 per year; and
·
Societal Risk Guidelines as stipulated in
EIAO-TM are shown in Figure 12.1. For definitions of the individual and
societal risk measures see Section 12.12.
Figure 12.1 Societal Risk
Guidelines for Acceptable Risk Levels (EIAO-TM)
12.2.2
The Sha Tin WTW is designated as a
Potentially Hazardous Installation (PHI) owing to its use and storage of
chlorine in 1-tonne (1t) drums. A Consultation Zone (CZ), centred at the Chlorination
House, of 1000m radius but excluding the areas located at over 150 m above sea
level is established around the WTW (Figure 12.2). The Hong Kong Planning Standards and Guidelines
(HKPSG), Chapter 12, require that PHIs comply with Hong Kong Risk Guidelines as
described above.
Figure 12.2 Sha Tin WTW
Location and Consultation Zone
12.3
Sha Tin Water Treatment Works: Location and Operations
12.3.1
Sha Tin WTW lies at the head of a valley on
Keng Hau Road, Hin Tin to the south-west of Sha Tin new town. The site is
approximately rectangular in shape and measures 400 m north to south by 300 m
east to west. The treatment plant comprises a South Works and a North Works.
The Chlorination House is located in the south-west corner of the site. The
site location is shown in Figure 12.2 and the existing
site layout in Figure 12.3.
12.3.2
Sha Tin WTW is located at 30 m above the
Principal Datum (PD) and is surrounded on three sides by hills rising to
approximately 300 m. To the north-east the land slopes gently downwards towards
the town of Sha Tin. The topography is of particular relevance; since chlorine
is a dense gas, the spread of a chlorine cloud from any large release would be
restricted by the neighbouring hills and directed towards the populated areas.
The topography of the site is shown in Figure 12.4.
Figure 12.3 Existing Layout of Sha Tin WTW
Figure 12.4 Topography of the Sha Tin WTW Area (not to scale)
Delivery, Storage and Handling of
Chlorine
12.3.3
Chlorine is delivered to Sha Tin WTW in
batches of up to 6×1-tonne drums. Unloading takes place inside the Chlorination
House, with the doors closed, in a designated truck unloading bay. The movement of drums
within the storage area and ‘drive-through’ unloading bay is carried out using
a hoist/monorail system with a purpose-built lifting beam. Prior to usage, the
drums are stored on cradles within the chlorine storage area.
12.3.4
The on-site chlorine delivery route is shown
in Figure 12.6.
Chlorination System
12.3.5
The draw-off units comprise of pairs of
drums, one drum on duty, the other serving as standby. The number of drums on
line is subject to the raw water quality. Changeover panels automatically
change the draw-off from duty to standby when the draw-off pressure falls below
a preset level. The changeover is achieved by electrically-actuated isolating
valves provided for each drum.
12.3.6
Liquid chlorine is drawn from the 1-tonne
drums and is passed to the evaporators for conversion into the gaseous state. The
gaseous chlorine passes through the chlorinators and dissolves in water at
ejectors to form chlorinated water for feeding into the bulk water stream
during the treatment process.
12.3.7
The chlorinators are of vacuum venturi type
and thus the section of line between the regulator and the chlorinator is at
negative pressure. This reduces the chances of chlorine leaks. Double non
return valves are provided within the chlorinator units.
Ventilation System
12.3.8
The chlorine drum storage area, evaporator
and chlorinator rooms are normally ventilated via a supply of fresh air at high
level which is extracted at low level. On detection of chlorine levels above 3
ppm there are visual and audible alarms, the ventilation fans stop and the
normally-open motorised louvres shut.
Chlorine Scrubbing System
12.3.9
An emergency chlorine scrubbing system is
installed to remove any leaked chlorine in the chlorine handling and storage
areas. The system is a packed tower utilising sodium hydroxide as the
neutralising agent. The plant and equipment are installed in a separate
scrubber room.
12.3.10
On detection of chlorine at a concentration
of 3 ppm or above in the chlorine handling or storage areas, the scrubbing
system will activate automatically. The air/chlorine mixture in the affected
areas is drawn into the scrubber by the scrubber fan via ducting connected to
the normal ventilation system. An electrically-operated isolating damper is
provided in the scrubber intake which opens automatically when the scrubber fan
starts up.
12.3.11
The scrubber system is normally set at auto
standby mode and is activated if the chlorine concentration rises above 3 ppm. A
continuous chlorine monitor is installed at a point downstream of the packed
tower and upstream of the vent/recycle changeover dampers to monitor the
scrubber performance; a “Chlorine concentration high” alarm will be initiated
if the concentration of chlorine in the tower exhaust exceeds the preset value.
12.3.12
The sodium hydroxide solution is of 10-12%
concentration and is held in a solution tank beneath the packed tower. When the
system is in operation, the sodium hydroxide is re-circulated by a pump to the
distributor at the top of the packed tower to provide adequate irrigation to
the packing. Sufficient solution is provided to absorb 1 tonne of chlorine. A
mist eliminator is provided at the top of the packed tower to prevent
entrainment of liquid into the treated air.
12.3.13
The scrubber is provided with the following
additional features: a sampling point, a top entry mixer (for preparation of the
sodium hydroxide solution), a direct reading transparent level gauge, an
inspection window and level indication with high and low level alarms and a
temperature measurement device for monitoring the temperature of caustic
solution during the preparation process.
Emergency Repair/Stoppage Kit for Chlorine
Spillage/Leakage
12.3.14
According to the Fire Services Department’s
fire safety requirements, an emergency repair/stoppage kit for chlorine
spillage/leakage is provided and maintained in good working condition at all
times for use by the trained persons and stowed adjacent to but outside the
store/plant room. Regular drills are conducted to train personnel on the proper
use of the breathing apparatus and protective clothing.
12.4
South
Works Reprovisioning
12.4.1
This project concerns a major reprovisioning
of the Sha Tin WTW South Works. During the reprovisioning, since parts of the
plant (i.e. the South Works) will have to be temporarily shut down, the water
throughput will decrease and accordingly, chlorine storage and usage levels will
be significantly reduced. Following completion of the reprovisioning water
throughput will return to 1,227 Mld.
12.4.2
The reprovisioning will involve introduction
of new treatment technologies for the South Works and construction of a number
of new facilities. Details are shown in Figure 12.5.
12.4.3
The current chlorine dosage levels are at or
below 2 mg/l. This will be reduced to 1.7 mg/l following the reprovisioning,
due to the introduction of new treatment technologies. This will result in a
permanent reduction in chlorine usage once reprovisioning is completed. Therefore,
it is worth highlighting that this is an improvement project that will lead to
a reduction in risks associated with the Sha Tin WTW. The operational parameters
of the WTW during and after the reprovisioning are presented in Table 12.1.
12.4.4
Before the start of the construction of
reprovisioning of South Works, 31 excess storage castors for storage of
chlorine drums will be carefully selected and to be removed from the
chlorination house (i.e. reduced from 221 castors to 190 castors before the
start of the construction works).
12.4.5
During and after the reprovisioning, the
existing on-site chlorine delivery route along the east & south & west
boundaries of the site will be replaced by the route along the east & north
& west site boundaries. Details are shown in Figure 12.6. The purpose of this is to separate the
existing North Works and the construction activities in order to maintain
continuous operation, maintenance and security of the existing North Works and
in particular to separate chlorine deliveries from the construction activities.
12.4.6
Details of the construction programme are provided
in Appendix
2.1. In general, the existing on-site chlorine delivery
route along the east & south & west boundaries of the site will be used
during Stage 1 of the reprovisioning and that along the east & north &
west boundaries of the site as shown in Figure 12.6 will be used for Stage 2; the intent being
to segregate chlorine delivery trucks from construction activities. Description
and locations of different construction activities are also provided in Appendix
12.8.
Figure 12.5 New Treatment
Facilities and Sha Tin WTW Layout following the Reprovisioning of South Works
Figure
12.6 Existing Chlorine Delivery Route at Sha Tin WTW and the New
Route to be used during and after the Reprovisioning of South Works
12.5
Scenarios
Considered in the QRA
12.5.1
Based on the South Works reprovisioning
schedule, two scenarios have been considered in the QRA. These are the Construction
Phase of this project and the Operational Phase following the completion of the
reprovisioning. The main assumptions used for each scenario, based on WTW
operational data provided by WSD, are listed in Table 12.1. Population data for the construction and
operational phase scenarios are projected to years 2016 and 2031, respectively.
Details of the population data for each assessment year are provided in Section 12.8 and Table 12.3.
12.5.2
The WTW operating data for these two
scenarios are consistent with Scenarios 2 and 4 of ERM (2011a).
Table 12.1 Scenarios
Considered in the QRA
|
Scenario |
Assessment year |
Maximum Chlorine Storage at WTW (tonnes) |
Chlorine Storage Time Distribution Assumed in the QRA
(tonnes, % of time) |
Average Chlorine Usage at WTW (tonnes per
year) |
|
Scenario
1: Construction Phase |
2016 |
158 |
158 (100%) |
642 |
|
Scenario
2: Operational
Phase |
2031 |
190 |
190 (20%) 150 (80%) |
761 |
QRA for the On-site Transport, Storage and Use of Chlorine
at Sha Tin WTW
12.6
Previous
Hazard Assessments for Sha Tin WTW
2001 QRA
12.6.1
In 1997, the Water Supplies Department (WSD)
commissioned ERM to carry out a Reassessment
of Chlorine Hazards for Eight Existing Water Treatment Works. The WTWs
considered were:
·
Au Tau WTW;
·
Pak Kong WTW;
·
Sha Tin WTW;
·
Sheung Shui WTW;
·
Tai Po Tau WTW;
·
Tsuen Wan WTW;
·
Tuen Mun WTW; and
·
Yau Kom Tau WTW.
12.6.2
The approved methodology for the above QRA
studies is detailed in the 8 WTW Study Methodology
Report (ERM, 1997).
12.6.3
Results for the Sha Tin WTW (ERM, 2001),
illustrated here in Figure 12.7 showed that:
·
The risk was in the ‘ALARP
region’; and
·
The maximum number N of fatalities was
assessed at over 900.
Figure
12.7 FN curve from the 2001 Sha Tin WTW Hazard
Assessment (ERM, 2001)
2011 QRA for Hin Keng Station and SCL Alignment
12.6.4
In 2008–2011, ERM conducted a QRA study on
behalf of MTRCL to assess the chlorine hazards related to the Sha Tin WTW
operations in connection with the proposed Sha Tin to Central Link (SCL)
project. This study assessed the impact of increased population from SCL work
areas, future SCL alignment and the proposed Hin Keng Station that will be
located within the Sha Tin WTW Consultation Zone (ERM, 2011a). The SCL QRA also
took into account the South Works reprovisioning that will proceed concurrently
with the SCL construction and the modified WTW operational parameters (chlorine
usage and storage quantities) during the reprovisioning and after its
completion.
12.6.5
The present QRA for the on-site transport,
storage and handling of chlorine at Sha Tin WTW follows the methodology of both
previous studies.
12.7
Meteorological
Data
12.7.1
For the sake of consistency, this study uses
the same meteorological data set as was used in the previous QRAs (ERM 2001, 2011a),
i.e. the data recorded at the Sha Tin weather station in the year 1996 by the
Hong Kong Observatory.
12.7.2
The weather data have been rationalised into
different combinations of wind direction, speed and atmospheric stability
class. The probabilities of occurrence of each combination during day and night
are presented in Table 12.2. The
Pasquill-Gifford stability classes range from A through F. Class A represents
extremely unstable conditions which typically occur under conditions of strong
daytime insolation. Class F on the other hand represents stable conditions
which typically arise on clear nights with little wind. Turbulent mixing, which
affects the dispersion of a chlorine cloud, increases through the stability
class range from F to A.
Table 12.2 Meteorological Data for Sha Tin Water Treatment Works
|
|
|
DAY Probability |
NIGHT Probability |
|
|||||
|
Direction |
Wind Speed (m/s): |
2.3 |
1.5 |
3.5 |
1.5 |
1.5 |
3.5 |
1.5 |
TOTAL |
|
|
Atmospheric |
B |
D |
D |
F |
D |
D |
F |
|
|
N |
|
0.0509 |
0.0380 |
0.0120 |
0.0153 |
0.0224 |
0.0045 |
0.0761 |
0.2191 |
|
NE |
|
0.0458 |
0.0228 |
0.0253 |
0.0149 |
0.0107 |
0.0239 |
0.0529 |
0.1963 |
|
E |
|
0.0450 |
0.0200 |
0.0299 |
0.0115 |
0.0116 |
0.0173 |
0.0774 |
0.2126 |
|
SE |
|
0.0146 |
0.0065 |
0.0059 |
0.0027 |
0.0023 |
0.0029 |
0.0233 |
0.0581 |
|
S |
|
0.0171 |
0.0106 |
0.0125 |
0.0042 |
0.0029 |
0.0050 |
0.0346 |
0.0868 |
|
SW |
|
0.0247 |
0.0113 |
0.0429 |
0.0050 |
0.0034 |
0.0103 |
0.0528 |
0.1504 |
|
W |
|
0.0023 |
0.0020 |
0.0004 |
0.0017 |
0.0018 |
0.0000 |
0.0139 |
0.0220 |
|
NW |
|
0.0038 |
0.0048 |
0.0059 |
0.0039 |
0.0036 |
0.0032 |
0.0294 |
0.0546 |
|
Total |
|
0.2042 |
0.1160 |
0.1346 |
0.0590 |
0.0587 |
0.0671 |
0.3604 |
1.0000 |
12.8
Population Data
General
Approach
12.8.1
The approach to the population data for this
study is the same as in the QRA for Sha Tin WTW for the SCL Project (ERM, 2011a).
The population data from the 2011 study were updated where applicable based on
more recent information.
12.8.2
The population data used in this study is
summarised in Table 12.3. A
definition of the time periods included in Table 12.3 is
provided in Appendix
12.6.
Sources
of Information
12.8.3
Population data for the South Works reprovisioning
workforce and Sha Tin WTW staff quarters were provided by WSD.
12.8.4
Railway-specific data such as SCL train and
station loadings for the Operational Phase, population of the Tai Wai MTR
Depot, number and locations of the SCL construction workers etc. were obtained
from MTRCL.
12.8.5
The Planning Department provided the GIS
coverage of Tertiary Planning Units (TPUs) further divided into Street Blocks
(SB). Detailed TPU-based population data and their projections to the future
are publicly available from the Plan-D website.
12.8.6
The Territory Population and Employment Data
Matrix (TPEDM) population projections for different Planning Data Zones (PDZ)
were also obtained from PlanD. These were used to obtain population projections
up to the year 2031 and the average household size for different areas.
12.8.7
Hong Kong conducts a population census once
every ten years and a by-census in the middle of the intercensal period. By-census
differs from a full census in not having a complete headcount but enquiring on
the detailed characteristics of the population on the basis of a large sample.
Census data is presented on Centamap website ([1]) for most
building groups and the population is further updated based on Territory
Planning Unit (TPU) Large Street Block (SB) population from 2011 Census.
12.8.8
If the population data was not directly
available, data on the number of floors and units of the residential
developments were obtained from the Centamap website and, together with the
TPEDM data on average household size, were used to estimate the current
population of these developments.
12.8.9
The Centamap website was also used to verify
the locations and/or further existence of the population units assumed in the
previous assessments and to check for any new developments that may have been recently
constructed.
12.8.10
Daily attendance data at Hin Tin Swimming
Pool and the highest and average daily usage data for the Hin Tin Playground
were obtained from Leisure and Cultural Services Department (LCSD).
12.8.11
Most of the road populations were estimated
based on the Annual Average Daily Traffic (AADT) data from the Transport
Department’s (TD) Annual Traffic Census 2013 ([2]) which is the
latest available data.
12.8.12
Recent data for the Tsing Sha Highway and
Lion Rock Tunnel, such as Staff in administration building, toll plaza, etc.
were obtained from TD in 2014 ([3]).
12.8.13
A site survey covering a large part of the
area within the 1-km CZ considered in the study was conducted by ERM personnel
on 28 April 2009. An additional site survey of the areas to be affected by the
SCL project site was conducted in July 2011. Another site survey was conducted
in Jan 2014 to further update the population.
12.8.14
Although site surveys indicated no population
at the Beacon Hill North Offtake Station, Towngas has since advised that a
number of their staff are located on this site from time to time. This
population has therefore been included in this assessment taking into
consideration both the site surveys and the Towngas information. However, this
has no significant impact on the results.
12.8.15
For most kindergartens, primary and secondary
schools and colleges, data from the Education Bureau website ([4]) was used.
This included the number of classrooms and the capacity of each classroom.
12.8.16
For cases where population data were not
available from publicly available data sources, the required information was
obtained by telephone interviews and e-mail inquiries.
12.8.17
The percentages of the maximum population
present (occupancy) at different times of the day and the indoor/outdoor
fractions for the total unit population are consistent with those used in the
previous QRA (ERM, 2011a).
Population
Units
12.8.18
The population units are defined for the QRA
purposes in the form of GIS-based polygons, points and lines. Outside the WTW
site the units used in this study are the same as in the previous QRA (ERM, 2011a)
however more detailed population units for different South Works reprovisioning
work areas are considered.
12.8.19
The full list of population units considered
is provided in Table 12.3 and their
locations shown in Figure 12.8 and Figure 12.9. The
population units within the 1-km Consultation Zone of the WTW are referenced
with letters while those outside the CZ are denoted by numbers.
South
Works Reprovisioning Work Areas and Workforce Population Data
12.8.20
Based on information provided by WSD, eight population
polygons, T1 to T8 (see Figure 12.8, Figure 12.9 and Figure 12.10) have
been defined for different project work areas at the WTW. Details on the
construction activities within each of these areas are provided in Appendix
12.8.
12.8.21
Since a different number of workers will be
needed for each construction activity and the activities at different site
areas will occur at different times, the total number of workers on site will
be changing and there will be no period when the workforce will be present
simultaneously in all locations. A conservative case was therefore selected
with a relatively high total population of 198 construction workers and
resident site staff (RSS) for supervision of the construction activities
simultaneously present at areas T1, T2 and T5. The resulting total numbers of
people at each site for this representative period are shown in Table 12.3. These
198 construction and RSS workers are conservatively assumed to be present year
round.
12.8.22
It is assumed that 10% of the 85 construction
workers and 50% of the 113 RSS will be located indoors. Thus, at each site, the
average proportion of people indoors can be estimated at (8.5 + 56.5)/(85 + 113)
= 33%.
12.8.23
It may be noted that the spatial distribution
of the reprovisioning workers and number of workers are different from those
assumed in the SCL QRA (ERM, 2011a). These have been revised based on updated
information provided by WSD. The SCL QRA assumed a uniform density of workers
over the southern works area whereas a more detailed spatial distribution is
now available as adopted in the current assessment. The estimated number of
workers has increased based on the latest project schedule. These changes,
however, do not have a significant impact on the analysis.
12.8.24
The WTW has a reception facility for visitors
as an integrated part of the WTW. The
visitor reception facility is located within the boundary fence of the WTW,
which walk-in visitors are not allowed.
Only visitors permitted by WSD are allowed to enter into the boundary of
the WTW. In addition, visitors will be
briefed on the safety and emergency procedures in case of fire and chlorine
leak. Visitors will also be escorted by
WSD staff when they are within the WTW.
Figure 12.8 Population Units used in QRA (figure 1 of 2)
Figure 12.9 Population Units used in QRA (figure 2 of 2)
Figure 12.10 Population Units for the Reprovisioning Works
Population Forecast
12.8.25
The residential population levels determined as
described above have been scaled up or down according to the population trends
determined from the area-specific TPEDM PDZ-based projections. For construction
phase, the maximum population between 2011 and 2016 will be used. For
operational phase, the maximum population between 2011, 2016 and 2031 will be
used. Relevant scaling factors are listed in Appendix
12.6.
12.8.26
The methodology of this scaling is consistent
with that used in the SCL Project QRA (ERM 2011a) except population is update
based on the latest available data.
12.8.27
As no information on the future traffic
trends was available for the road population and the examination of past
traffic data shows no significant upward traffic trend over recent years, the
road population numbers derived from the 2013 Traffic Census were not further
projected to the future years.