Bedrock resources and their use in Helsinki

SPECIAL SECTION: USES OF THE SUBSURFACE IN FINLAND 0886-7798(94)0(026-3

Editor's note: The papers in this special section are adapted from presentations at the IFHP International Congress 1993 (=Cities for Tomorrow') session on =BuildingAbove and Below Ground," and are reprinted herein with the permission of the authors and the Congress organizers.

Bedrock Resources and Their Use in Helsinki U. Anttikoski, T. Niini, d. Ylinen and A. Ruoppa

A b s t r a c t - - F i n l a n d ' s geology lends itself to development o f underground space, and Helsinki has used its subsurface for an increasing variety of purposes. In the Finnish capital city, several city planning offices--including the Geotechnical Department, the Building Supervision Office, and the City Planning Department-are involved in the process of subsurface space development. The paper provides an overview of current and possible future uses of Helsinki's bedrock resource, and describes the Rock Engineering 2000 Technology Programme now underway.

1. Introduction n recent years, planning and construction activities in Helsinki have focused increasingly on the use of underground space as an alternative to aboveground building. There are many valid reasons for doing so. The city centre is located on a narrow peninsula where plot land is expensive. The intensifying needs for space for various activities, and traffic requirements in particular, cannot be met at a reasonable cost at ground level. Construction activity in Finland encounters bedrock almost everywhere. The loose soil layer is thin, often just 0-10 m deep. Finnish geology comprises only the oldest and youngest strata, the =covers of the geological handbook'. The hard, solid bedrock includes fracture zones. The surface of bedrock in Helsinki is between +60 and -60 m. Because t-nnelling in Finland is confined almost exclusively to the bedrock, it causes no distur-

I

Present address: Usko Anttikoski, City of Helsinki Real Estate Office, Geotechnical Department, Maimin asematie 3A, 00700 Helsinki, Finland;Timo N'fini,CityPlanning Department, Helsinki, Finland; Jsakko Ylinen, Architect Office, Kaupunkisuunnittelu Oy; and Aarne Ruoppa, Association of Finnish Civil Engineers (RIL), Meritullinkatu 16A5, 00170, Helsinki, Finland.

bance to aboveground activities. Tunnels are excavated by the drill-andblast method. Full-face boring, which is about 20-40% more expensive than drill-and-blast, is not yet competitive. Rockengineeringis economical. The cost of a structure built in the bedrock is comparable to that of equivalent aboveground bui]dinL~s. When plot land is required only for entry points, constructions in rock are even cheaper than their aboveground counterparts. Energy consumption in rock caverns is about 30% lower than at ground level. This paper examines underground construction based on experiences in Helslnki. Two books published by the Finniah TunnellingAesociation--Rock Engineering in F i n l a n d (1986) and The Rock Engineering Alternative (1988)-have aroused significant interest in using the underground resource. The books, which deal extensively with underground construction in Helsinki and other areas of Finland, emphasize the importance of careful design of subsurface spaces.

2. Rock Resources and Current Underground Space Uses in Helsinki U n d e r g r o u n d construction presumes that the city authorities possess accurate information about bedrock, subsurface spaces, ducts, and their environmental impacts. To this end, the City of Helsinki Geotechnical Depart-

Tunnellingand UndergroundSpate Technology, Vol. 9, No. 3, pp. 36.5-372, 1994 Copyright (~) 1994 E[sevier Science Ltd Printed in (,rear Britain. All righls reserved 9886-7798/94 $7.00 + .00

ment maintains a database that ineludes information about the following topics related to underground space use:

• Soil investigations: maps and sections. • F o u n d a t i o n s t r u c t u r e s of old buildings. • Design layouts of constructed reck tunnels. • Control measurements of groundwater and soil. In 1992, the Helsinki Geotechnical Department published a bedrock resource map of the inner city area, based on rock surveys. This investigation divides rock resources into two categories: 1. S u r f a c e rock, denoting rock masses at a depth of 20 m or less from the ground level. 2. Deep rock, denoting rock masses at depths exceeding 20 m. However, rock masses are examined to a maximum depth of only 50 m. Rock resources in the city are determined to be usable when existing tunnels, including their buffer zones, are subtracted from the surface and deep rock areas. The City Survey Department has positional information on constructed rock tnnnels and technical ducts of municipal plants and departments. The Building Supervision Office has layouts of basements and tnnnels that

~ Pergamon 365

require a building permit. In addition, the City V]Annlng Department maintains a space allocation plan m a p for underground activities. This map presents the space requirements for subsurface construction. At the beginning of 1993, the Helsinki region included 6 million m s of constructed rock spaces. This translates into a specific subsurface space use of 12 mS/citizen, divided among the following purposes: • Fuel caverns: 1.0 million m s • Civil defense shelters: 1.1 million m s • Technical utility tunnels: 3.2 million m s • Metro tunnels: 0.6 million m s • Other spaces: 0.1 million m s In addition, the 120-kin-long drinking water tunnel from P~iijiinne to Helsinki, which has a capacity of 2 million m s, is the world's longest single rock tunnel. Taking this tunnel into account, the total length of excavated tunnels is 300 kin. Table 1 compares rock resources with floor areas of aboveground buildings, and indicates the average growth rate of these spaces. Since only 5% and 1% of the surface rock and deep rock, respectively, have been used, it may be deduced that the inner city still has abundant virgin rock resources. The City of Helslnki Real Estate Office has published a geotechnical map (1989) at 1:10,000 scale and a bedrock resource map (1992) for use in planning s u b s u r f a c e c o n s t r u c t i o n in Helsinki.

Figure 1. Clean water reservoirs associated w i t h water treatment p l a n t s are built in bedrock. I n Helsinki, typical dimensions o f such reservoirs are 130 m (length) x 15 m (width). Water height is 9.3 m.

20% of the total cost of the project. Sewage tunnels (typical cross-section: 13 m 2) with a concrete base typically cost Fim7000/m ($US1300/m). Multipurpose tunnels (30 m2), including their pipe systems, cost approximately Fim25,000/m ($US4500/m), 45% of which constitutes excavation and reinforcement. The cost of a single car space in a carpark cavern facility built in rock, including an access road, is Fire100,000 (US$18,000). If the cavern is fitted for bomb shelter purposes, the cost of the carpark facility increases to Fiml50,000. Generally the cost of a rock space in Finland averages Fim250/m s or Fiml,500/m 2. Engineering costs add another 30 to 300 percent, depending on how the space will be used. The lowest costs are incurred for storage spaces, whereas operating plants are

3. Costs Rock engineering costs in Finland are very low when construction is performed in favourable conditions. Excavation and reinforcement of the Viikinm~d underground wastewater treatment plant cost Fim200/m s (37 US$/mS), a figure that represents only

the most expensive. Larger structures typically lower the costs.

4. Infrastructure of Underground Spaces Potable water for Helsinki is conducted from Lake Piiij~nne via a rock tunnel for transporting raw water. The water purification plant is located aboveground. Some water reservoirs are partly underground (see Fig. 1); others are tall water towers aboveground. To a large extent, water is distributed to the various city areas via multipurpose rock tunnels. Wastewater treatment and its associated conveyance systems are mainly situated in bedrock tunnels. Until recently, Helsinki has had a maximum of 11treatment plants in operation. When the Viikinm~iki underground central

Table 1. Com ~arative costs o f rock resources with floor areas o f aboveground buildings.

Office Premises (ir~ 1,000 sq. m)

Residential (in 1,000 sq. m)

Rock Spaces (in 1,000 sq. m)

Unused Resource (in 1,000 sq. m)

Growth Area of

/yr.

G/Y

G/Y

G/Y

CA'

G/Y

199397

1993

198792

199397

1993

198792

1993 -97

Helsinki

1993

198792

Entire City

22,000

368

290

15,600

354

240

1,200

80

30

• Inner city

8,640

64

80

9,300

131

100

800

50

15

• Suburbs

13,360

304

210

6,300

223

150

400

30

15

•Southem district (city centre)

5,260

24

40

5,500

32

40

500

20

10

366 TUNNELLINGANDUNDERGROUNDSPACETECHNOLOGY

Surface rock

Deep

28,000

35,000

10,000

14,000

rock

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Figure 2. Utility tunnels accommodate district heating and water pipes, together with electricity and communication cables. treatment plant begins operations in 1994, all surface plants will be abolished (see the article by K/imppi in this issue of T&UST). This centralization of Helsinki's water treatment system will free up 30 ha of plot land for other uses. The treated wastewater will be discharged into the sea via a 7-km-long rock tunnel that will remove the nutrient load far from the shore. Powerplants. One peak-level heating plant is situated in bedrock; the rest are aboveground. Equipment shelters and oil caverns (volume appreximately 1.0 million m s) have also been constructed inside the bedrock. Multipurpose rock tunnels have been built to handle district heating, water conveyance, data communications, and some electricity conduction simultaneously (see Fig. 2). After 1995, these tunnels will total 30 k m in length. The general cleanliness of the densely built urban zones of I-Ielslnki, reflected in the nickname ~White City of the North," derives largely from the fact that the entire city area has been linked to the district heating network. Instead of thousands of chimneys rising from house-specific heating systems, Helsinki has only a few tall chimneys, which associated with power-gen-

Volume 9, Number 3, 1994

erating plants. In recent years, these have been fitted with efficient flue gasdesulphurization devices. The city's centralized power systems will make future development of purification appliances easily possible. Because of Finland's arctic weather conditions, heating accounts for more than 50% of the nation's overall energy balance. Municipal depots and storages have subsurface components, including six sand bunkers. Traffic networks. Because the city centre is situated on a narrow peninsula, Helslnki's increasing space requirements for traffic cannot be satisfied aboveground at reasonable cost. Therefore, some of the city's traffic must be directed underground. The most important subsurface route is the metro (see Fig. 3). There are also a few short railway tunnels, and just one car traffic tunnel (Mallaskatu concrete tunnel). Other developments have included s h o r t service t u n n e l s and carpark tunnels. Helsinki has about 8,000 parking places in basements and another 2,000 p a r k i n g p l a c e s in rock c a v e r n s . Aboveground spaces total approximately 10,000. All of these figures apply to the inner city area.

Of Helsinki's 640,000 civil defense spaces, 20~ (120,000) are inside reck caverns. However, because their distribution within the city does not correspond to actual shelter requirements, an additional 150,000-200,000 spaces are needed. The civil defense law stipulates t h a t shelter spaces should constitute 2% of the floor space for buildings exceeding 600 m 2in area. Alternatively, defense shelters m a y be created in reck spaces constructed by the municipality. Various peacetime uses of these spaces can include carparks, sports halls (Fig. 4), and warehouses (Fig. 5). The injunction to construct defense shelters has increased the number of underground spaces significantly and rendered them financially competitive. For longer-term civil defense needs, rock shelters are better t h a n the concrete shelters of buildings. They are designed to be spacious, thus permitting longer periods of occupation. In a "nuclear winter ~ situation, the bedreck would offer a base temperature of +7°C, even if technical maintenance systems malfunctioned. Water supply from the bedrock is also possible, and even shelter from the effects of an atomic explosion is feasible. The im-

Ttrm~LLING ANDUNDERGROUNDSPACETECHNOLOGY367

Figure 3. Helsinki metro tunnel. The platform section combines the texture of shotcreted rock with the smooth concrete used for the platform.

proved security and well-being of citizens to be gained from such shelters has a beneficial psychological effect, derived from certain knowledge of available shelter within the bedrock, safe from the external world.

5. Underground Buildings Underground rock buildings in Helsinki have been a reality in past centuries. Suomenlinna Castle, which belongs to the coastal archipelago and is called the "Nordic Gibraltar," once housed in its excavated rock spaces more inhabitants than the city on the mainland. Helsinki's newest and most significant two-level rock engineering project is the Viikinmiiki central wastewater treatment plant, mentioned above. The plant, designed to serve the entire Helsinki region, is located in reck caverns beneath a new housing area. Indirect benefits of the project include other housing estates that will become available when several separate, old t r e a t m e n t plants are demolished, thereby freeing up coastal land plots. O t h e r e x a m p l e s of s u b s u r f a c e projects in Helsinki include: • The Forum shopping centre and underground car park. • The recently completed It/ikeskus swimming pool (see T& U S T 9:1, "News and CommenC). • Kontula sports hall and civil defense shelter. • Re-use of the Kofffactory estate. • A combined municipal base and sports hall project: the Merihaka sports-hall/civil defense shelter plan.

The neighbouring municipalities of Espoo and Kauniainen also have developed several underground sites, including: • Traffic tunnels (see Fig. 6). • KAnnunsillAnmaki multi-activity centre, near Espoo Town Hall. • Kauniainen ballgames hall.

6. New Traffic Route Plans In recent decades, the Helsinki city centre and inner city have witnessed a marked decrease in the number ofavail-

able parking spaces on land plots. This has permitted the continuation of a high level of quality in public transport and service for traffic heading into the city centre. From the standpoint of city traffic and motorcar use policies, the decisive factor is whether the State will finance large-scale transverse route plans. If it does, the two important main road crosstown connections for the inner city peninsula will be transferred into rock tunnels. A general plan for the Pdisilanvdiyld crosstown route was completed in 1992. This route involves the main road crossconnection of the northern section of the inner city. The route would connect and distribute traffic from the five most important moterways into the city centre road network. The aim of this plan is to transform the Pasila area into an extension of the business centre following demolition of the city railway yard. In the last decade, the area has witnessed significant construction of office premises, including several state offices. According to the proposed plan, the 7.5-kin route would comprise 4 km of rock and concrete tunnels, which would account for half of the total Fim1750 million cost of the project. The Keskustankehdi City-Centre RingRoute is a similar east-west crossconnection in the business centre, proposed in the 1992 master plan for Helsinki. The ring road would serve two functions equally: (1) connecting Helsinki peninsula's southern section and business centre, and (2) carrying traffic through the centre.

Figure 4. The Hervanta ice hockey hall has a span of 32 m and a length of 134 m

3 6 8 TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY

Volume 9, Number 3, 1994

In addition to the city centre main reads, the KeskustA nkeh~i route would connect directly with the city centre service and car parking facilities. Preliminary plans propose construction oI this route by the cut-and-cover method across the widest platform section of the main railway station. Rock tunnels, which would reduce disturbances during the construction period, have also been proposed. After preliminary surveys are completed, the plAnn;ug will continue toward fulfilling a general design, adhering to criteria determined by the town plan requirements for the area. A Railway Ring Tunnel in the city centre has been proposed, but no general plan has yet been presented. The system would effect rapid conveyance of passengers to the city centre sites, and would implement an unbroken connoction to the metro and tramway. Such a scheme would increase the useful capacity of railway utilities. The current centre railway site, which is overly wide, could be transformed partly into plot land or used for traffic.

7. New Engineering Possibilities Large spans are feasible in the Nordic bedrock. Caverns in Finland have a maximum width of 30-40 m, but theoretical calculations have been performed for caverns 50-100 m wide. The Olympic ice-hockey hall in Gjcvik, Norway, is 61 m in diameter. Thus, the upper limit for spans has not yet been approached. Automated factories in caverns are suitable even in urban subsurface location, where delivery distances for products are short. There are several automated tall storage spaces in Helsinki. Plot land is required only for the entry points. High-speed trains are increasingly being used in other countries. Because fast trains cause environmental disturbances such as noise, vibration and air pressure, it is difficult to obtain permission to construct such connections in residential areas. Locating these ~bullet" (shuttle) trains in tunnels would reduce or eliminate such negative environmental effects. Air pressure in the tunnels could be decreased by 90% through pumping. The ensuing reduction in air resistance would permit speeds of 300-500 km]h. Underground stations would be at normal pressure and have airtight connections to the shuttle. Since flight traffic will be limited for environmental reasons in the future, underground shuttles offer an alternative to flight connections. Border tunnels in Finland will be feasible in the next century. The map of Finland's geology (Geologia 1992) indicates that the solid Precambrian

Volume 9, Number 3, 1994

Figure 5. Interior of an underground Red Cross supply warehouse, part of which is equipped as an S l-elass civil defense shelter.

bedrock connects Finland both to east and west. The same bedrock exists beneath Tallinn at 150 m depth. Current tunnelling technology in Finland and Sweden makes it possible to pass under both the Gulf of Bothnia and the Gulf of Finland, and to build tunnels for technical maintenance and traffic. Municipal waste treatment and repositories m a y be sited in deep rock excavations (30-60 m). Such facilities require less space than standard surface landfills. Emissions to the environment m a y be prevented by grouting the rock and using pumping to maintain the water level in the excavation at a lower level than the surrounding water table. The excavated stone is a viable alternative to other soil material. Sustainable development is ensured by underground construction. The built environment may be condensed and its many "livability ~ factors improved by satisfying certain space requirements underground. In addition, rock constructions are very durable, cheap to construct, and energy-efficient.

Traffic noise remains behind in tunnels, and vehicle emissions may be filtered through tunnel ventilation systems. Exhaust air emissions (traffic fumes and dust) from the aforementioned Helsinki city centre ring route could be totally eliminated by conducting the air to power plants located near both ends of the route. Across-section of the tunnel is shown in Figure 7. The power plants use combustion air for coal at a rate similar to the exhaust air produced by the traffic tunnel on designed scale. The crosssectional ventilation of the tunnel uses a parallel service tunnel such that

nearly all of the exhaust air can be purified in the power stations. Thus the energy content of the exhaust gases may be utilized while rendering them non-noxious. Purification ofceld gases is not economically feasible. However, it will be possible to use the energy content of the exhaust fumes, by hot afterburning, resulting in excellent air purification.

8. City Planning of Underground Spaces Private ownership of land in Finland dominates most of the concerns regarding urban building land. Land ownership is usually considered to extend to the earth's core, although the town plan and local building regulations limit the owner's usufructuary rights. According to such regulations, only two subsurface basement levels are permitted unless a special permit from the local authority is obtained. However, as the capital city, Helsinki owns a considerable amount of land associated with historical sites. At its founding, the Crown donated considerable land to the city. Subsequently, the city has leased this land for use by developers. As a coastal city, half of Helsinki's area is water. Ownership of the 185 km 2 of ground area can be divided as follows: City 64%; Private, 22%; State, 14%. The p o p u l a t i o n d e n s i t y (pop. 500,000) is 2,500 inhabitants per km 2. One-third of the land area is constructed plot ground; another one-third comprises parkland, forests and recre-

TUNNELLINGANDUNDERGROUNDSPACETECHNOLOGY3 6 9

ii~ ¸

Figure 6. Street traffic tunnel in Espoo. ation areas. Traffic-related uses account for 15% of the total land area. The town plan is the essential directiv.e instrument in city planning. It defines the rights of landowners regarding construction and other landuse. In Finland, the compilation and updating of town plans is the monopoly of the municipality. In order to coordinate changes in the town plan, munici-

palities produce more general master plans (or component master plans) every 10 years. A yet more extensive regional plan for directing master plans is compiled by the regional planning association, which comprises several municipalities. The planning system is defined in the Building Act. Two-level townplans have been applied thus far to extensive underground

projects. The practice has been to use separate plans for deep spaces and surface buildings with basements, respectively. The aboveground plan has included all stairs, shat~s, and other constructions that extend up to the surface. The problem has been that because underground buildings are not considered as independent real estate, they

F-.,,y

Figure 7. Proposed route for the Helsinki ring-road tunnel.

370 Tt~NELLINOANDUNDERGROUNDSPACETECHNOLOGY

Volume 9, Number 3, 1994

¢0

CR

FJ

Q

~D CD

i--i

F[

1.2 Construction methods and equipment for small rock caverns

1.1 Typical lay-outs for rock caverns (1993)

Construction Techniques for Small Rock Caverns

2.3 Waterproofing and frost isolation structures: their installation and fire protection (1993-1995)

2.2 Development of drainage channels in shotcreted structures and mechanised installation (1991-1993)

2.1 Development of grouting techniques and code of practice (1991-1994)

3.8 Corrosion on rock bolts (1991-1992)

3.7 Blasting vibrations and threshold values for structures and sensitive installations (1992-1995)

3.6 Drilling and blasting in long tunnel rounds

6.5 Principles and methods in rock mechanical design (combined with 6.4)

6.3 Interpretation of information registered during boring and core drilling (1992-1994)

6.2 Correlation between site investigations and real rock structure (combined with 6.4)

6.1 Deformation and strength properties of the bedrock (combined with 6.4)

Rock Mechsnlca and Site Investigations

3.5 Automization and guidance systems for explosives charging

5.3 Underground city planning technology

5.2 Standardisation of contract documents and risk-sharing systems

5.1 Development of cost management systems (1994-1995)

Utllisstion

Underground

6.4 Utilisation of site investigations in rock mechanics design (1992-1995)

4.3 Structural systems in underground facilities (1994-1995)

4.2 Construction techniques for radiation shelters (combined with 4.3)

4.1 Problems in construction works in underground facilities (1991-1992)

Economy and Management of

3.4 Utilisation of shafts in excavation of caverns and tunnels (1991-1992)

3.3 Integrated navigation system for drilling, location measurements and control of excavation profile

3.2 Utilisation of the information registered during drilling (combined with 6.3)

3.1 Effect of blasting and rock quality on the excavation profile

Excavation Techniques

Groutlng and

Dralnage Methods

Construction Works In Underground Facilities

7.4 Lighting in underground facilities

7.3 Energy balance in underground facilities (combined with 7.2)

7.2 Design of ventilation systems (1993-1995)

7.1 Problems in heating and ventilation (1991-1992)

Ventilation and Heating Systems

Table 2. Projects originally comprising the Rock Engineering 2000 Technology Programme. Some projects have since been combined to support the research effort.

can not be claimed as mortgages to back loans. Even questions concerning postal addresses present difficulties. However, not all underground constructions require town plans, because Finnish law lacks a definition of a new construction. A new underground construction is generally regarded as a space housing offices, or a public area such as a metro stations.

Building Law Development The essential building law is revised annually. The 1990 revision added a basis for ensuring sustainable development in principle (see Section 7, above). Because of the special nature of underground space town planning, minor modifications to the law and its regulations have been proposed. Majorrevisions are being prspared with a view toward E U needs. Developments concern the entire land-use planning system, local building regulations, and approval of building types and accessories at the national level. An Environmental Impact Assessment (EIA) is mandatory for all large projects. The town planning system also uses it, in a reduced mode, for smaller projects. Because our common environment is seriously threatened, ensuring the viability of an efficient, healthy and beautiful city requires that even "invisible" underground projects be presented to the public as early as possible in the planning process. This enables m a n y bodies to participate in the EIA, and allows those with the best available technology to prepare for project realization according to the sustainable development principle.

9. Rock Engineering 2000 Technology Programme Underground construction is currently undergoing significantdevelopment. The Finnish Tunnelling Association,together with the Association of Finnish Civil Engineers, has initiated a Rock Engineering 2000 Technology Programme. Some 50 companies and organizations are involved in the project,which includes 30 separate research projects. The programme cost is approximately Fire20 million, more than half of which is being contributed by the participating organizations. The technology programme for rock engineering was initiated in 1991 and will run through 1995. The main objective of the programme, which is divided into 30 separate projects, is to

cover the whole field of rock engineering and rock space utilization through an interdisciplinary approach. Since it began, the program has come to include other underground construction activities t h a t relate to the bedrock. The project aims to develop technology in various ways. It has seemed particularly advantageous to make more extensive use of the project resuits by compiling technical directives for integrated planning of subsurface construction. Adraft of this sub-project was drawn up in spring 1992; its implementation awaits financial backing from the Finnish Ministry for the Environment, on terms (50%) similar to those currently practised by the Technology Development Centre (TEKES) concerning the actual technology projects. Table 2 lists the projects comprising the original programme. Some projects have since been combined to support the research effort. Of the projects planned, 21 have been started and 7 are awaiting final approval. Projects now in the "active" stage are those in which financing companies have the most interest. Starting new projects in their full extent will require increasing financial resources from both TEKES and industry. Company and organization financing has almost doubled since May 1991, and this trend will probably continue during the next three years. In order to fully utilize all results and ideas gained from other projects, care has been exercised in the starting sequence of projects associated with the structural features of underground construction. The seven phases of the Underground City P l a n n i n g Technology project (Item 5.3 in Table 2) are: P h a s e 1: Collect information on the current technical basis and procedures for underground city planning, and on the main problmatic aspects of such planning. P h a s e 2: Conductageneralstudy on the technical, economic, ecological, physiological and human aspects of activities to be located underground. The aim of this phase is to orient the planning work properly. P h a s e 3: Develop s u r v e y a n d characterization methods of rock structure for different planning phases on the basis of the "engineering geological rock classification" principle embodied in projects 6.3 and 6.4. P h a s e 4: Compile standard layouts for directing area and space allo-

372 TtrNNELLINO AND UNDERGROUND SPACE TECHNOLOGY

cation for different kinds of rock caverns and tunnels. This aspect also includes application instructions for use of layouts in planning and for Phase 6 (see below). P h a s e 5. Compile standard layouts for normal procedures related to construction of these spaces (e.g., excavation, grouting, drainage) for use in planning work and implementation of Phase 6. P h a s e 6: Develop cost surveys according to the evaluation procedure for building components, on the basis of the standard designs of Phases 4 and 5. Easy and reliable updating of cost data will be an aim of this phase. P h a s e 7: This phase comprises the following tasks: 1. Formulate instructions for addressing technical and economic aspects of city planning for rock/ underground spaces, together with any necessary calculation procedures for the planning economics. This work will be based on the results of Phases 3 through 6. 2. Compile environmental impact assessment directives for beth positive and negative effects of rock/underground construction. 3. Issue recommendations for a uniform system of plan legends and m a r k i n g s for u n d e r g r o u n d spaces, consistent with other city plan marking systems. At various stages, attempts will be made to apply or test this development work in ongoing planning projects. In this respect, investment by the various municipalities in specific zone areas is essential. []

References City of Helsinki Real Estate Office, Geotechnical Department. 1989. "Geotechnical Map? City of Helsinki Real Estate Office, GeotechnicalDepartment. 1992. "Inner City Rock Resource Map." Finnish Tunnelling Association. 1986. Rock Engineering in Finland. Helsinki: Finnish Tunnelling Association. FinnishTunnellingAssociation. 1988. The Rock Engineering Alternative. Helsinki: Finnish Tunnelling Association. Finnish Tunnelling Association. 1992. "City Planners' Notions on Rock Spaces". Helsinki: Finnish Tunnelling Association. National Survey Board and Finnish Geographical Society. 1992. Atlas of Finland, books 123-126. Helsinki: Geologia.

Volume 9, N u m b e r 3, 1994