APPENDIX A

1 JUSTIFICATION FOR THE PROJECT

1.1 General

1.1.1 This section of the appendix presents the detailed justification for the Project. Attention is drawn in this appendix to the issue of safety. As the existing Tung Chung Road is grossly sub-standard, carries a significant proportion of buses and coaches, and experiences an increasing number of traffic accidents, the proposed road improvement is considered essential. Although Government has introduced operational controls in an attempt to maintain safe traffic conditions on Tung Chung Road, the numbers of traffic accidents and casualties are already considered high. As such, the proposed road improvement is required now as a matter of urgency to rectify this undesirable situation on the existing road.

1.2 Current Traffic Arrangements on Tung Chung Road

1.2.1 At present, Tung Chung Road is the only existing vehicular access between North and South Lantau. The road is about 6.9 km long, and connects Tung Chung in the north with South Lantau Road, near Cheung Sha, in the south.

1.2.2 The existing road is characterised by steep gradients and sharp bends. About 3.9 km of the road is steeper than 10% gradient, of which about 2.1 km exceeds 15% gradient, as shown in Figure A1. About 500 m of road is actually up to about 20% gradient. In this respect, the alignment of the road is grossly substandard. In fact, no other existing public road in the SAR has such long and steep gradients.

1.2.3 The road has a carriageway width of generally 3.5 m, and along its length there are about 40 passing-bays, which can only accommodate 1 to 2 vehicles at a time. As such, the road operates under single-lane two-way traffic conditions over much of its length, and has a total (two-way) maximum capacity of only about 100 vehicles per hour.

1.2.4 As the road has severe traffic safety and capacity problems, it is subject to usage control. There are two forms of usage control in South Lantau, which are currently in place for Tung Chung Road, as follows:

· the Lantau Closed Road (LCR) permit system; and

· the Tung Chung Road Prohibited Zone (TCRPZ) permit system.

1.2.5 The South Lantau road network is closed to all motor vehicles, except those authorised by the Commissioner for Transport. LCR permits are only issued to full-time residents of Lantau Island (excluding North Lantau New Town, Discovery Bay and Chek Lap Kok Airport), limited companies which are property owners on Lantau Island and other applications on justification. As at the end of 2001, 3,374 vehicles were issued with LCR permits.

1.2.6 Tung Chung Road was designated as a prohibited zone in June 1991 to facilitate the construction of Tung Chung of the North Lantau New Town and Chek Lap Kok Airport. There is a 24-hour prohibition on use of the road by medium and heavy goods vehicles, and a prohibition on its use by other vehicles between 8:00 am and 6:00 pm. The only vehicles that are exempted from the prohibition are franchised buses, Lantau taxis, emergency vehicles and vehicles with TCRPZ permits.

1.2.7 Motorists who need to use Tung Chung Road during the prohibited hours are required to obtain both LCR and TCRPZ permits. These are only issued to persons or companies that need to use the roads concerned to carry out construction/ maintenance works or to transport goods and materials. Applications from persons who have general transport needs or ordinary sightseers are not considered, and public transport should be used instead.

1.2.8 The implementation of the LCR and TCRPZ permit systems is enforced by the Police. The enforcement statistics for 1998 to 2001 are presented in Table A1 below.

Table A1: Statistics on Enforcement Action against Permit Abusers on Lantau Island

Offence	1998	1999	2000	2001
Driving on closed road without permit	875	1267	732	234
Driving in prohibited zone (ie, Tung Chung Road) without permit	351	392	434	274
Breach of permit condition (ie, TCRPZ permit)	4	8	2	1

Source: Hong Kong Police Force

1.3 Existing Traffic Conditions on Tung Chung Road

1.3.1 Since the opening of the North Lantau Highway, Chek Lap Kok Airport and the developments in Tung Chung, the traffic demand between north and south Lantau has increased significantly.

1.3.2 Three automatic traffic count (ATC) stations are located in the vicinity of the study area. In order to examine the historic growth, results from these three ATCs are presented in Table A2 below and illustrated graphically in Figure A2.

Table A2: Historic Traffic Flows for Tung Chung Road and South Lantau Road

Site: Description of Road Section	Station No.	No. of Vehicles (Annual Average Daily Two Way Traffic)
		1992	1993	1994	1995	1996	1997	1998	1999	2000
Tung Chung Road (South Lantau Road/Tung Chung Ferry Pier)	5256	230	250	340	340	330	340	1820	1680	1680
South Lantau Road (Chi Ma Wan Road/Tung Chung Road; north east of junction with Tung Chung Road)	6054	1570	1750	1640	1630	1600	2050	2450	2350	2350
South Lantau Road (Tung Chung Road/Sham Wat Road; south west of junction with Tung Chung Road)	5859	1270	1300	1220	1210	1490	1610	1600	1530	1530

Source: Transport Department

1.3.3 The historic flows indicate a steady level of daily traffic on Tung Chung Road between 1992 and 1997, with a dramatic increase observed in 1998; this “spike” suggests that an increased number of TCRPZ permits were issued sometime during this period. The sharp increase corresponds with the opening of the Tsing Ma Bridge and Chek Lap Kok Airport and the provision of the MTR to Tung Chung; and the change in access to South Lantau; switching from use of ferry at Mui Wo to use of Tung Chung Road. Analysis of the traffic on South Lantau Road shows there is no large traffic increase at the junction with Sham Wat Road, although there is some increase in the section to Mui Wo. This patterns supports the view that there was a general growth in traffic to South Lantau in 1998 carried by Tung Chung Road together with some switching in overall access which lead to significant increases in Tung Chung Road.

1.3.4 In Figure A2, it can be seen that traffic flows to Mui Wo are consistently higher than those to Ngong Ping / Tai O. Traffic to Mui Wo increased dramatically between 1996 and 1998, while an increase occurred between 1995 and 1996 for traffic to Ngong Ping / Tai O.

1.3.5 For 1999, flows for all three ATCs have decreased compared with the peak, which occurred in 1998. This could be attributed to the effects of the economic slow down, and the completion of construction work at the airport.

1.3.6 It should be noted, however, that due to the restrictions imposed by the two permit systems, the observed historic growth is likely to exclude an unquantified element of suppressed demand.

1.3.7 As part of the traffic impact assessment for the Assignment, the Consultants undertook their own traffic surveys in 2001. The surveys found significant traffic growth compared with the previous surveys carried out in 1996 by the same Consultants for the “Widening of Tung Chung Road Feasibility Study” (Agreement No. CE 26/96). Between 1996 and 2001, traffic has grown by a factor of 3.4 during the weekday (Monday to Saturday) and 5.9 at the weekend (Sunday). Clearly, there has been significant underlying growth of traffic since 1996 even with the permit system in effect. Table A2 shows that in 1998 there was a large growth of traffic on Tung Chung Road similar to that found by the Consultants.

1.4 Accident Statistics for Tung Chung Road

1.4.1 There is now mounting pressure from local residents in South Lantau to relax the TCRPZ permit system to allow all South Lantau residents to drive freely to and from the rest of Hong Kong. However, relaxing the TCRPZ permit system would lead to unacceptable traffic congestion on the existing road and increase the accident risk. Indeed, the number of accidents on the road has increased with the level of traffic, with a significant increase between 1998 and 2001. The accident statistics for the existing road bewteen1990 and 2001 (up to September) are presented in Table A3 below.

Table A3: Accident Statistics for Tung Chung Road between 1990 and 2001 (up to September)

Year	No. of Accidents	No. of Casualties
1990	0	Not Known
1991	1	Not Known
1992	3	Not Known
1993	4	Not Known
1994	5	Not Known
1995	5	1
1996	7	2
1997	7	2
1998	21	5
1999	35	8
2000	65	64
2001 (up to Sep)	30	22

Source: Hong Kong Police Force

1.4.2 The existing gradients of Tung Chung Road and the locations of traffic accidents on the road from 1998 to 2001 (up to September) are shown in Figure A3. During that period, the average number of traffic accidents per kilometre of road in relation to different gradients of the road are as follows:

· gradient less than 10%: 14.3 accidents per km of road;

· gradient between 10% and 15%: 12.2 accidents per km of road; and

· gradient between 15% and 20%: 30.0 accidents per km of road.

1.4.3 The accident rates on sections of road with gradients less than 10% and with gradients between 10% and 15% are about the same. However, the accident rate more than doubles on sections of road with gradients between 15% and 20%. The above figures show that the sections of the road with steeper gradients are apt to have more traffic accidents.

1.4.4 The contributory factors of traffic accidents on the existing road bewteen1997 and 2001 (up to September) are presented in Table A4 below. The figures show that 25% of accidents on the existing road are due to loss of vehicle control and 19% are due to driving too fast for the road conditions. Furthermore, 16% of accidents are due to reversing negligently, most probably when making space for opposing traffic to pass along the single-lane sections of the existing road.

Table A4: Contributory Factors of Traffic Accidents on Tung Chung Road between 1997 and 2001 (up to September)

Ref. No.	Factor Description	No. of Accidents	%
1	Driving too fast for the road conditions	30	19.0
2	Driver starting negligently	1	0.6
3	Failing to maintain a safe braking distance	15	9.5
4	Failing to keep to nearside of road	1	0.6
5	Overtaking on nearside / offside	4	2.5
6	Reversing negligently	25	15.8
7	Turning right / left negligently	3	1.9
8	Rolling backwards / forwards – failing to set handbrake	1	0.6
9	Driving inattentively	20	12.7
10	Sleep / fatigue	1	0.6
11	Consumption of alcohol	2	1.3
12	Loss of vehicle control	39	24.7
13	Swerved to avoid collision	1	0.6
14	Overloading	1	0.6
15	Passenger lost balance	2	1.3
16	Pedestrian jay-walking	2	1.3
17	Mechanical defect	3	1.9
18	Other factors	7	4.5
Total:		158	100

Source: Hong Kong Police Force

1.5 Future Year Traffic Flows on Improved Road

1.5.1 The purpose of the Project is to improve the sub-standard Tung Chung Road to meet the essential safety standards and the traffic need between North and South Lantau. The improved road will still be operated as a closed road to prevent vehicles from the rest of Hong Kong, without LCR permits, from entering South Lantau. Subject to further analysis, the current TCRPZ permit system might also require retention with appropriate modification to manage traffic on the improved road and tightly control its growth.

1.5.2 The improved road will comprise a two-lane two-way rural road. Although gradients will be as steep as 15% in sections, a climbing lane will not be provided to minimise the environmental impacts of the improved road. Instead, passing bays will be provided. As such, the improved road will only have a total two-way capacity of about 1,450 pcu/hr. The speed limit will be 50 kph, similar to other rural roads in Hong Kong.

1.5.3 The Consultants have calculated future year traffic flows for the improved road for planning and design purposes, including the environmental impact assessment (ie, air quality, noise and hazard to life assessments). The forecasts were based on the future population assumptions given in the “South West New Territories Development Strategy Review – Recommended Development Strategy”. The future year traffic flows are presented in Tables A5 and A6.

Table A5: Future Year Traffic Flows on Improved Road (with LCR permit system only) (pcu/hr)

Direction of Travel	2006		2011		2016
Direction of Travel	AM	PM	AM	PM	AM	PM
NB	450	520	570	620	660	730
SB	550	480	650	590	760	700
2-way	1000	1000	1220	1210	1420	1430

Table A6: Future Year Traffic Flows on Improved Road (with LCR and TCRPZ permit systems) (pcu/hr)

Direction of Travel	2006		2011		2016
Direction of Travel	AM	PM	AM	PM	AM	PM
NB	180	140	300	250	400	320
SB	140	120	250	210	310	260
2-way	320	260	550	460	710	580

1.5.4 Two sets of traffic forecasts were calculated; both with the LCR permit system, but with and without the TCRPZ permit system. The traffic impact assessment found that the improved road would have sufficient capacity for the future population, with only the LCR permit system in operation. This is not surprising given that the planned growth in the population in South Lantau is relatively small, in line with the recommended strategy for conservation and environmentally sustainable recreational development along the South Lantau Coast.

1.5.5 The first set of traffic forecasts (ie, with the LCR permit system only) have been used in the environmental impact assessment, since these figures are higher than the second set, and are therefore conservative.

1.5.6 The traffic forecasts take account of the ferry services and the proposed cable-car between Tung Chung and Ngong Ping. If the cable-car does not proceed, the estimated PM-peak flows would increase accordingly, since these flows include tourism and recreation traffic. However, the cable-car would not affect the AM-peak flows, since these flows generally comprise early morning commuting traffic, which would most likely occur outside the operating hours of the cable-car. Furthermore, the cable-car would not attract many commuters, because its characteristics and location will be designed for the quite distinct tourism and recreational markets.

1.6 Conclusions and Recommendations

1.6.1 The improved road is required to overcome the road traffic safety problems associated with the existing road and allow more residents in South Lantau to use the road. Simply increasing the number of TCRPZ permits for the existing road is not a practical option, since the existing road cannot accommodate any more traffic, since it is sub-standard and inherently unsafe.

1.6.2 It is recommended that the improved road comprise a two-lane two-way rural road, with gradients as steep as 15% and no climbing lane to minimise the environmental impacts of the improved road. This configuration is considered the minimum acceptable improvement, and will have sufficient capacity for the future population of South Lantau.

1.6.3 There is no doubt that the improved road is required urgently to overcome the road traffic safety problems associated with the existing road, and accommodate the current aspirations of the people of South Lantau and meet the future needs of the local communities.

2 COMMENTS FROM RELEVANT PUBLIC BODIES

2.1 General

2.1.1 During the periods when Government carried out its review of the possible solutions to improve the north-south vehicular access on Lantau and the Consultants undertook this Assignment, various public bodies were consulted. Members of these bodies generally expressed no objection in principle to the Project, and urged government to expedite the implementation of the Project. In addition, they made a number of comments and suggestions. These are summarised below in italic, together with the Consultants’ responses.

2.2 Country and Marine Parks Board (CMPB)

2.2.1 At the CMPB meeting on 11 January 2001, some members expressed the following comments:

(i) to consider the construction of a short tunnel under Pak Kung Au

Two short tunnel options were included in the alignment options assessment, but did not score the highest overall marks (see Appendix B – Alignment Options Assessment). It was found that a short tunnel would only improve the gradient for the section of road in the tunnel. The approach roads to the tunnel options would still require gradients as steep as those required for the overland options. Although a short tunnel would reduce the length of the road slightly, it would add a significant cost to the Project. A tunnel solution would likely cost more than twice that of an overland solution. The tunnel options, although scoring highest marks for landscape and visual, did not score the highest overall marks for the environmental criteria. Indeed, since the tunnel portals would be located relatively close above the Tung Chung and Cheung Sha streams for both options, there was considerable concern as to the potential water quality impacts on these streams during construction of a short tunnel.

(ii) to shift the southern end of the road alignment westward to avoid Cheung Sha Stream

Options S2B and S3 and were developed to investigate this possibility in the alignment options assessment (see Appendix B – Alignment Options Assessment). However, given the hilly topography between the existing road and the catchwater, it proved very difficult to find a good route. Both options involve extensive earthworks and large amounts of bridge works. These factors led to the options scoring the lowest total marks in the option assessment.

(iii) to use the future obsolete sections of Tung Chung Road as a walking trail

The use of the future obsolete sections of the existing road as a walking trail is fully supported (See Appendix B - Alignment Options Assessment and Section 2 - Project Description).

(iv) to reduce the visual impact of the soil removal and tree felling

The potential visual impacts arising from the future construction of the improved road have been minimised as far as possible by minimising the footprint of the new road by adopting steeper than normal gradients and by minimising the extent of earthworks by using retaining walls and elevated structures (see Section 2 – Project Description). The large tracts of existing plantation woodland along the alignment will also help screen the construction works.

(v) to dispose the excess soil of the slope cutting properly

The selected alignment option has the least surplus excavated material requiring disposal off-site. The surplus material will be disposed of at public filling facilities or at other Government projects requiring fill material. The haulage of the surplus material will be controlled by a trip-ticketing system (see Section 7 – Waste Management).

(vi) to request the contractors to avoid damage to the environment

The construction works undertaken by the Contractor will be supervised not only by the Engineer for the project, but also subject to weekly environmental audits by both the Environmental Team and the Independent Checker (Environment). In this way, practices with are affecting, or have the potential to affect, the environment and/or are in breach of the recommendations of the EIA or the Environmental Permit conditions will be highlighted and measures taken to rectify the situation.

(vii) to reduce the footpath width to 0.5 metre

Unfortunately this is not possible. For the off-line section of the improved road, a minimum width of 1.6 m is recommended for the footway on one side of the road, together with a minimum width of 1.25 for the paved verge on the opposite side of the road. These widths are required to accommodate the, crash barriers, street lighting and the utilities to operate the road, including lighting cables, traffic surveillance and control cables and watermain for fire hydrants (see Section 2 – Project Description).

2.3 Country Parks Committee (CPC)

2.3.1 At the CPC meeting on 19 November 2001, some members expressed the following comments:

(i) the dry season surveys should also cover the other alignment options

The dry season surveys undertaken by the Consultants cover all the alignment options considered in the option assessment (see Section 8 – Ecology and Appendix H).

(ii) the water gathering ground should not be polluted

Careful consideration has been given to the water quality impacts associated with both the construction and operational phases of the Project (see Section 6 – Water Quality). The permanent drainage system will comprise special carriers pipes that discharge the carriageway runoff outside of the water gathering grounds. This will be an improvement on the existing situation, in so far as there is no drainage system along the existing road. During construction, any site runoff north of the crest at Pak Kung Au will be directed into the permanent drainage system, which will be constructed ahead of the main roadworks, and will thereby avoid the water gathering grounds. In the south, the site runoff will be discharged via settlement tanks and filters to clean the water as much as possible.

2.4 Advisory Council on the Environment (ACE)

2.4.1 At the ACE meeting on 27 February 2001, some members expressed the following concerns:

(i) mitigation measures and post-construction management of the mitigation measures

The majority of the mitigation measures recommended are relevant to the construction phase only and such post construction management will not be relevant. However, certain measures, such as the compensatory planting, will be monitored not only during the construction phase but also during the first year of the operation of the road by the Environmental Team and IC(E) to ensure the proper establishment and integrity of the measures. Subsequent to that such measures will be the responsibility of Government and management and maintenance agents will be identified.

(ii) plans and actions to preserve organisms in the streams near the alignment

The onus has been on the avoidance of impacts on the streams and its flora and fauna in the first instance as far as possible. Based upon this, the road alignment has been designed accordingly with mitigation integrated into the design. Direct impacts on streams which have been identified as supporting key ecological factors have been avoided, as far as possible, by the road passing over them on elevated structure. In addition, it is proposed to construct part of the permanent drainage system prior to the construction works in the northern area in order to collect all the run-off and discharge into the Tung Chung Nullah after treatment. While this system is not possible for the southern section, all run-off will be treated via a sedimentation tank before discharge. No operational road run-off will enter any of the streams with the implementation of the special pipeline system. In addition, to these measures, all haul road will cross over the streams on temporary bridges and a series of recommendations for the control of waste material and stockpiles have been proposed to avoid indirect impacts to streams.

(iii) means to reduce cutting slopes and landscape impact

As discussed above, the extent of cutting slopes and the landscape impacts have been minimised as far as possible by minimising the footprint of the new road by adopting steeper than normal gradients and by using retaining walls and elevated structures (see Section 2 – Project Description).

(iv) future development in South Lantau

As discussed above, fears over any consequential developments arising from the Project may be largely allayed, since the improved road will only comprise a two-lane two-way rural road, with gradients as steep as 15% and no climbing lane to minimise the environmental impacts of the improved road. As such, the improved road will only have a total two-way capacity of about 1,450 pcu/hour. Furthermore, the improved road will remain a closed road to prevent vehicles from the rest of Hong Kong, without LCR permits, from entering South Lantau. Subject to further analysis, the current TCRPZ permit system might also require retention with appropriate modification to manage traffic on the improved road and tightly control its growth. The improved road will only have sufficient capacity for the planned growth in the population envisaged under the “South West New Territories Development Strategy Review – Recommended Development Strategy”.

(v) traffic control management on the new road

As discussed above, the improved road will be operated as a closed road in a similar manner to the existing road to prevent vehicles from the rest of Hong Kong, without LCR permits, from entering South Lantau. Subject to further analysis, the current TCRPZ permit system might also require retention with appropriate modification to manage traffic on the improved road and tightly control its growth.

(vi) causes of traffic accidents on Tung Chung Road

The accident statistics compiled by the Hong Kong Police show that 25% of accidents on the existing road are due to loss of vehicle control and 19% are due to driving too fast for the road conditions. Furthermore, 16% of accidents are due to reversing negligently. The statistics also show that the number of accidents per km of road where the gradient exceeds 15% is more than twice that per km of road where the gradient is less than 15%. This should be of no surprise, given the very steep gradients and hairpin bends over the steeper sections of the existing road. Clearly, reducing the gradients, deleting the hairpin bends and widening the road to two-lane standard can improve road safety. Further details of the accident statistics can be found in Appendix A (Justification for the Project).

2.5 ACE EIA Subcommittee

2.5.1 At the ACE EIA Subcommittee meeting on 5 November 2001, some members expressed the following comments:

(i) attention should be paid to construction impacts of bridges on the streams

The new road has been designed to minimise the amount of elevated structure along the hillside to minimise the visual impacts. However, structures are required to traverse the larger streams along the route as part of the ecological mitigation. Most of these structures will comprise single span bridges. Furthermore, all the structures have been designed with relatively straight alignments and relatively short span lengths to facilitate the use of prefabricated deck construction, or the use of falsework supported by the abutments and piers for insitu construction, to avoid disturbing the streams during construction (see Section 6 – Water Quality and Section 8 – Ecology).

(ii) the road should be able to cater for future traffic demand

As discussed above, the improved road will have sufficient capacity to cater for the planned growth in population envisaged under the “South West New Territories Development Strategy Review – Recommended Development Strategy”.

2.6 LegCo Panel on Transport

2.6.1 At the Panel's meeting on 19 January 2001, some members had the following comments:

(i) to use the old Tung Chung Road for one-way traffic

This suggestion was examined as part of the development and assessment of the various alignment options for the proposed road improvement (see Appendix B - Alignment Options Assessment). The suggestion is not recommended, since the overall cost saving to the Project would only amount to about 6%, and the overall saving in Country Park land affected by the Project would only amount to about 7% (less than 1 ha). Also, use of the obsolete sections of the old road, even in the uphill direction, would still be hazardous to motorists. In this respect, it is most likely that Government would be criticised for not providing a “sensible” or “proper” solution. The one-way traffic scenario is also not suited to the selected preferred alignment for the new road, given the separation between the existing and new junctions with South Lantau Road. Finally, if the obsolete sections of the old road were used for one-way traffic, then they would not be able to accommodate the new services requested by the utility authorities (see Section 2 – Project Description).

(ii) to explain the future policy of issuing permits for using Tung Chung Road

As discussed above, the improved road will remain subject to the LCR permit system to prevent vehicles from the rest of Hong Kong, without LCR permits, from entering South Lantau. Subject to further analysis, the current TCRPZ permit system might also require retention with appropriate modification to manage traffic on the improved road and tightly control its growth.

(iii) to maintain traffic on Tung Chung Road during construction

Since the existing Tung Chung Road is the only north-south vehicular access on Lantau, it is important that the road remains open during construction. Temporary traffic management measures will be derived to enable the improved road to be constructed whilst maintaining traffic on the existing road. This is particularly relevant to the on-line widening section of the road improvement.

(iv) to explain the capacity of the new road

As discussed above, the improved road will comprise a two-lane two-way rural road. The speed limit will be 50 kph, similar to other rural roads in Hong Kong. Although gradients will be as steep as 15% in sections, a climbing lane will not be provided to minimise the environmental impacts of the improved road. Instead, passing bays will be provided. As such, the improved road will only have a total two-way capacity of about 1,450 pcu/hr, which will cater for the planned growth in population envisaged under the “South West New Territories Development Strategy Review – Recommended Development Strategy”.

(v) to explain future planning policy of Lantau

As discussed above, the current planning strategy for South Lantau is detailed in the “South West New Territories Development Strategy Review – Recommended Development Strategy Final Report”. This Project forms one of the recommendations of the report.

(vi) to use a short tunnel

As discussed above, two short tunnel options were included in the alignment options assessment, but did not score the highest overall marks (see Appendix B – Alignment Options Assessment). It was found that a short tunnel would only improve the gradient for the section of road in the tunnel. The approach roads to the tunnel options would still require gradients as steep as those required for the overland options. Although a short tunnel would reduce the length of the road slightly, it would add a significant cost to the Project. A tunnel solution would likely cost more than twice that of an overland solution. The tunnel options, although scoring highest marks for landscape and visual, did not score the highest overall marks for the environmental criteria. Indeed, since the tunnel portals would be located relatively close above the Tung Chung and Cheung Sha streams for both options, there was considerable concern as to the potential water quality impacts on these streams during construction of a short tunnel.