Prefeasibility Studies

An international consultant, SOFRETU, was engaged in 1992 to carry out a prefeasibility study. Prefeasibility studies have been accomplished in 3 stages:

1. Evaluation and correction the existing studies.
2. Determining the main transportation corridors in present year and planning year.
3. Determining suitable transport system which can respond to the public transport need in planning year.

Feasibility Studies

An international consultant, PPK from Australia, was engaged to carry out a feasibility study in 1996.
Data from the prefeasibility studies formed the base data for input into the feasibility including types of modes, main transport corridors, and forecast demands in those corridors based on future population, employment and car ownership. This data was reviewed, updated and expanded during the feasibility.

The objectives of the studies were:

• To carry out a study to investigate the feasibility of a suitable rapid mass transit for the City of the Esfahan and the region.
• To complete the preliminary design of the priority line within the city and one within the region.
• To carry out a more detailed economic and financial evaluation of the priority lines;

Corridors identified in the prefeasibility to be studied for the introduction of rail or exclusive bus way assessed and a preliminary alignment developed using existing survey and geological data. The feasibility studies compared a total of 22 different alignment options and modes within each corridor, examined the constraints to those alignments and presented a proffered preliminary alignment for each mode of transport studied.

The corridors studied pass world significant and ancient heritage buildings, traverses along both grand boulevards and narrow streets, and pass through planned satellite cities and open rural areas. Throughout the study area the well developed infrastructure provides a constraint to the mass transit development. The alignment which was developed is in sympathy with the high heritage quality of the city and its regions.

The alignments were chosen so as to minimize the impacts with known Master Plan objectives of the Regional cities. These objectives had to be balanced by constraints to capital or operating costs. The main objectives were, therefore:

• To allow minimal building and streetscape impacts in the inner city district by using only below ground alignments.
• By incorporating where possible aspects of the Master Plans of the cities in the region but avoiding expensive and sometimes practically infeasible spurs into city centers.
• This was achieved by locating interchanges at the edges of the regional cities with car and bus feeders to these interchanges.
• By developing technical solutions which minimized construction difficulty and cost impacts of the adverse geographical features such as the mountainous area such as Poolad Shahr and the shallow water laden natural gravels below and either side of the Zayandeh Rud.
• Taking note of and allowing for utility relocations, storm water and sewer lines and existing road and bridges in the conceptual design of the alignment alternatives.
• Minimizing property acquisition and social disruption by constructing high level tunnels in the inner city, and elevating rail viaducts in the outer city within existing or proposed road reserves.

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Transport Demand

The input into the transport demands studies were the trip tables of future traffic estimate produced as part of the prefeasibility work. These were reviewed and updated and compared against existing on street traffic. External traffic and freight traffic were also estimated and included in the modeled flows.

The major task of the traffic demand work was to estimate the amount of traffic which would divert to the new mode (rail or bus way) when it was introduced. Because this is a new mode in Esfahan (and Iran generally) there was no historical data to use. A stated preference survey was, therefore, carried out in Esfahan to determine under what conditions of cost and time savings or increases people would transfer to the new mode from cars, taxis and other vehicles. The data so obtained was then modeled in order to calculate demand for the new mode under varying conditions and in the different transport corridors.

The entire transport network was modeled both with and without the new mode and the traffic assigned to the network links. The year 2011 was used as the forecast year, however, traffic growth and link flows were extrapolated up to year 2020, and assumed as 20 years after start of construction. 22 different transport networks were compiled to give a range of alignment and mode combinations. These included both complete and partial networks so as to give a program of staged construction for final recommended network.

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Multi Criteria Analysis

The method used in this study was to evaluate each network against a set of objectives to be achieved, such as maximizing economic benefits or ionizing adverse environmental impact, and to rank each network alternatives based on how it achieved those objectives. The criteria selected were:

• Economic Worth
• Financial Worth
• Strategic Development
• Future Growth of the system
• Regional Development
• Regional Equity
• Heritage Conservation
• Environment
• Iranian Input

Quantitative criteria such as economic worth and meeting transport demand were measured directly from the results of the demand modeling. Qualitative criteria were assessed by the Consultants and counterparts by examining each of the 22 networks together and rating them in terms of their achievement of each criterion.

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Geological Studies

:: Geological Setting
The majority of the study area is relatively flat and is underlain by Quaternary deposits (described as “recent terraces and recent alluviums “) and then by lower Jurassic (Lias) bedrock deposits comprising Shale containing ammonites with intercalation of conglomerate, sandstone, radiolarite limestone and volcanics. The topography of the area changes from level plains to areas characterized by hilly and mountainous ground, to the south of the city. The geology also changes in this area with the absence of alluvial and Lias bedrock deposits and the occurrence of Lower Cretaceous limestone, conglomerate and sandstone dominating the geological setting. As the Quaternary deposits vary across the city and because they are a critical consideration in assessment of possible tunneling options, a slightly more detail summary of their composition is given below.

The Quaternary deposits in the Esfahan City area consist of the following formations:

:: Fan Deposits or Alluvial
These deposits comprise silty clays, angular/sub angular gravel and sand. Some cobbles and lenses of fine grained deposits with different percentages of sand and gravel also occur.
Information on the minimum and maximum particle size of the granular deposits (particularly the cobbles) could not be found. These deposits evidently generally occur in the southern parts of the city.
The central and northern parts of the city are underlain by the Zayandeh Rud deposits which are discussed below.

:: Zayandeh Rud
These deposits generally consist of either fluvial or flood plain deposits. The thickness of these deposits generally increases from around 15 meter and their southern extremity to what is described as “considerably increasing towards the north of the city”.
No comment as to the likely maximum thickness of these deposits has been given. The fluvial deposits are mostly clean (i.e. little fines) coarse grained deposits (i.e. well poorly graded, surrounded to rounded gravel and sand with some cobbles). These deposits also contain some lenses of fine sand (quoted as occasionally being of considerable thickness) and some lenses of silty and/or clayey deposits.

These fluvial deposits can apparently form a semi hard to hard conglomerate lenses amongst the uncommented clean particles, by local cementation of the soil particles by a calcium carbonate matrix.
The size and proportion of cobbles within these deposits needs to be established, since they may have a significant impact on the feasibility of certain methods of construction.
The flood plain deposits comprise silt and clay of low to high plasticity, with some sand and gravel in varying proportions. Apparently, the Quaternary deposits are generally covered by agricultural soils which are under cultivation in undeveloped areas. Some central city areas are also covered by fill (maximum 4-5 meter thick) which comprises fine grained soils with coarse particles and building waste.

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:: Ground Water
The supplied geotechnical cross sections indicate that in some instances this means that the surface of the ground water table occurs within the near surface fine grained clayey soils. It is uncertain whether this means that the clays are therefore saturated and presumably soft or whether the ground water level shown on the cross sections is actually a line of piezometric head.
If the latter is the case, it would suggest that the upper gravel aquifer is running with an “ artesian head “. This aspect needs to be further clarified prior to finalizing our analysis and comments. Up to 3 separate aquifer have been identified within the Quaternary soil profile.
A shallow aquifer ( of variable thickness but up to 30 meters maximum) exist in the upper level clean coarse grained Zayandeh Rud deposits. This is an unconfined whose base is defined by the lower level fine grained silty/clayey soils of the Zayandeh Rud deposits.

The permeability coefficient of the coarse grained deposits is estimated to be approximately 0.01 m/s. This corresponds to a transitivity of approximately 0.3 m2/s for a 30 meter thick aquifer. The second aquifer is a confined aquifer which exists between 2 layers of silty/clayey soils in the lower level of the Zayandeh Rud deposits.
This aquifer generally occurs below 30 meter depth and extends to the northern and western parts of the city. The thickness of these aquifer is also variable but can be up to 30 meter thick.
The permeability coefficient of the coarse grained deposits is estimated to be approximately 0.01 m/s. This corresponds to a transitivity of approximately 0.3 m2/s for a 30 meter thick aquifer. A third unconfined aquifer has been identified in the southern parts of the city, and occurs near the base of the alluvial deposits and is only 5 meter in maximum thickness.

Apparently the upper levels of the Jurassic bedrock also contribute to this aquifer due to its relatively high permeability associated with open fractures and weathering. However , it appears that the lower level bedrock is less permeable and forms the base of this aquifer.
The permeability of this aquifer is significantly less than the above mentioned aquifers with a permeability coefficient of approximately 1µm/s and transitivity of 5 µm2/s (5 m thick aquifer).

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