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Building a Transport GIS In Manipur

Manipur is one of the seven North-Eastern States in India with a total area of 22,327 sq. km.and a population now of just over two million. Imphal, the centrally located capital has an elevation of about 800m above sea level .To the east and south east of Manipur is Myanmar, to the north is Nagaland; to the west is Assam and to the south-west is Mizoram. In 1991 the population of Manipur was 1,837,149. There are nine Districts: –

Valley:

Imphal (East pop 330,480) & (West pop 380,801), Thoubal (pop 293,958), and Bishnupur (pop 180,773)

Hills:

Senapati (pop 208,406), Ukhrul (pop 109,275), Chandel (71,014), Churachandpur (pop 176,184) and Tamenglong (pop 86,278)

The Imphal Valley (1,843 sq km) is surrounded by hills which rise in places to 3,000 m. Another smaller valley at or near sea level lies on the western border between the Barak and Jiri rivers (395 sq km). Whereas the valleys comprise about 10% of the land area they are the home to over two thirds of the people. Loktak Lake – the largest in NE India lies in the Imphal Valley varies in size from 60 to 260 sq km depending on the season.

The climate is pleasant with temperatures ranging from 0 to 38 degrees. Rains occur during the south-west monsoon generally from June to September and weather is cooler and drier for the remaining months. At the airport the rainfall May through August averages 225mm compared to 35mm November through March. In the hill regions the steep gradients create fast run-off of surface water leading to low water retention in the soil and also to landslips interrupting transport communications. Due to poor drainage the rains cause many roads to become impassable.

The oldest rocks in Manipur include shales, slates, siltstone, sandstone and quartzites. Geologically, Manipur can be said to belong to recent formation, which has implications on the prospect of mineral exploitation. The surface rock is loose and soft in nature and, therefore vulnerable to the weathering process. This peculiar characteristic also accentuates erosion, silting and sedimentation.

Hill soils being acidic are not suitable for much plant growth and traditional shifting cultivation together with indiscriminate cutting and burning of forest (jhum) over the years have seriously affected the ecological balance leaving the soil barren. In the valley region the deep soils are poorly drained and low in available phosphorus content. They are also susceptible to flood hazards. Peat soils are found in the low-lying areas and marshy lands around Loktak Lake.

In 1987 the total length of surfaced roads including National and State Highways, Major and Other District Roads and Inter-Village Roads was 4,279 km.

Manipur is one of the least industrialized states in India. Limited infrastructure and inadequate power supply do not help this situation.

The PCCS Project (Project Co-ordinating Consultancy Services)

The Government of India is proposing, with the help of a World Bank Loan to prepare a major state’ roads upgrading, major maintenance and rehabilitation program with the aim to stimulate economic development by improving accessibility.

The project started with the Strategic Options Study; the result of which was the identification of 1,300 km of State, Major District and Other District road to be assessed in more detail in the Feasibility Study, which is now in progress. (National Highways, Inter-Village and Village Roads are excluded from the project). To assist this work a comprehensive Transport GIS has been built.

Major Components of the GIS

The major components of the GIS are:

  • Road Network
  • Towns, Villages
  • Public Transport
  • Earth Sciences
  • Raster Images including Topographical Mapping
  • Other

Before looking at each of the above components the choice of software, the method of digitizing and the use of handheld GPS are discussed.

Choice of Software

Some of the reasons, not necessarily in order of importance, for choosing MapInfo were

  • its successful application on other similar projects
  • SQL processor with string, numerical functions for analyzing geographic and non-geographic data.
  • Availability of ProViewer a MapInfo facility to provide mapping and information on a CD that can be viewed but not changed.
  • Interfaces with MS Office (Excel & Access), AutoCAD, ArcInfo
  • Buffer facility
  • Facility for heads-up digitizing (see below)
  • Ability to include photographs (or indeed other raster images in a table)
  • Ease of use to refine the digitizing of roads etc as the project progresses)
  • MapBasic – application language
  • Same “feel” as many Windows programs making it easier for senior staff to use.
  • Raster image processing
  • People, once trained in ArcInfo or AutoCAD, often move jobs to capitalize on their “new” skills

Method of Digitizing

The main methods of digitizing are:

  • Using A Digitizing Tablet (A0, A1 or A2),
  • Heads-Up i.e. displaying a registered raster image on the computer screen and then using a mouse trace a road or river or to pinpoint the centroid of a village or to pinpoint the location of a bridge or to specify the an area of say a District.
  • Manually from map sheets such as the 1:50,000 or 1:250,000 (usually limited to point objects)
  • Output from a handheld GPS. (Global Positioning System).

The Department of Earth Sciences, University of Manipur when they have undertaken digitizing for us has mostly used an A0 digitizing tablet. Tables (layers) digitized in this way were the transport network in NE India and 100 meter contours in the Imphal Valley and surrounding foothills. Before starting the digitizing the features – roads, contours are often traced and the tracing sheets placed on the A0 digitizing tablet. In this way the information such as contours or rivers from a number of 1:50,000 top sheets can be consolidated on one A0 tracing.

Most of the geographical data in the GIS was generated using the Heads-up Method. A big advantage is that with a notebook this method can be deployed anywhere – office, home, airport waiting room, in the garden or near the beach. Furthermore every computer in an office can be a “digitizing work station”. It is also possible to digitize initially by viewing top sheets at say a scale of 1:100,000 to get the GIS up and running and the refine the digitizing by viewing at a scale of between 1:25,000 and 1:50,000. Of course the ability to use this method requires maps to be scanned. The valley toposheets have been scanned using large format commercial scanners and the other maps available to us using a Logitech “Freescan” Scanner. Using the latter method toposheets are scanned as three strips. Large hand drawn or annotated blueprints can also be readily scanned.

The information that was initially digitized manually from toposheets was the locations of bridges and culverts – objects were assigned unique identifiers of the form G16.85 i.e. the 85th bridge/culvert identified on toposheet G16. It must be added that this process also served to familiarize staff to the co-ordinate system.

A hand-held GPS displays X and Y co-ordinates, altitude and trip distance. Whilst out on site the above information (excluding altitude which I have found to be unreliable in any event) can be automatically recorded as waypoints and downloaded back in the office. This method has been used to record the location of photographs – road condition, adjacent land coverage and the precise location of potential quarry sites. It has also been used to convert data such as roughness and strip plans that are recorded on a chainage basis to road links in the GIS. (Another application is to use the tracking facility to record the alignment of say, a road through the hills – the BCEOM team working on the Imphal – Ukhrul Road Project used this facility.)

Road Network

The road network is the “raison d’aªtre” of the GIS. Specifying the road network prior to digitizing was commenced on the first day of the study – end of May 1999. The source material was the list of road sections comprising State Highways, Major and Other District Roads together with a blue print (approximately 1:250,000 scale) with roads hand-colored – National Highways (NH) – black, State Highways (SH) – red, Major District Roads (MD – blue, and Other District Roads (OD) – green. The map also contained some Inter-Village Roads (IV) – yellow. The same color coding scheme was adopted in the GIS until recently when Inter-Village Roads are now shown with a black dashed line to facilitate photocopying the A1 size Manipur and individual district maps. The colored blueprints did not show the precise specification of all the road sections on the list.

Being blueprints the base maps had become distorted over time. Furthermore the alignment of the roads was imprecise – one only has to look at the alignment of roads on the 1:250,000 Map Sheets compared to the same roads on the 1:50,000 toposheets.

The first task was to sub-divide the specified Road Sections into links. Each link was allocated a Unique Link Identifier referred to as the LinkID. e.g. SH10.12 a link that is part of the Road Section numbered 10 in the list of State Highways. For example links making up SH10 were allocated LinkIDs – SH10.10, SH10.12, SH10.14 ‘¦’¦’¦’¦’¦ SH10.24 from start of the section (SH10.10) to the end of the section (SH10.24). The numbers start at 10 and increment by 2; incrementing by 2 allows an additional link to be inserted between two original links without affecting the sequence.

The links in the road network are stored in two tables – MAINroads – NH, SH, MD, OD and IVroads – InterVillage Roads. Nodes have been specified at the end of or at the intersections of roads in the Main Road Network. Nodes are not specified on Inter-Village Roads. The fields in the MAINroads table are: –

  • DIST – District
  • CLASS – Class (NH, SH, MD, OD)
  • RS – Road Section
  • RSdesc – Road Section Description
  • RSlength – Road Section – Length (as specified on the list of roads)
  • RStype – Road Section – type of construction
  • RScond – Road Section – condition of road (from PWD records)
  • RSwidh – Road Section – road width
  • LinkID
  • NA – node number at start of link
  • NB – node number at end of link
  • LEN – Length of link derived from the GIS. (using the function SphericalObjectLen)
  • GPSlen – Length of Link derived from GPS outputs from a drive along the Road Section)
  • Terrain – Type of Terrain
  • Flow – Traffic Flow
  • Capacity – Link Capacity
  • Rwidth – Road Width (from Strip Plan Survey where available)

In the table IVroads the fields RS, RSdesc, RSlength, RStype, RScond, RSwidth are dummy variables and are blank. As nodes are not specified on Inter-Village Roads NA and NB are also dummy variables and are blank.

The initial link digitization was based on 1:250,000 scale blueprints, this was later refined using individual district blue print maps. These maps proved to be inconsistent and the current digitization is based on the 1:50,000 toposheets. The roads having been drawn on photocopies of the toposheets .by the PWD Engineers with the most detailed knowledge of the districts. Checking and amending road specifications is a continuous process. The Road Network is shown in Figure 2 and the detailed coding in Figure 3.

An additional table – LinkIRI has been created from the Bump Integrator Survey, which was carried out along the Road Sections selected for the Feasibility Study on a chainage basis – one estimate of IRI for each kilometer was recorded. In LinkIRI the average IRI for the link together with range of IRI values along the link are stored.

A further table STRIPplans relates Strip Plan Drawing Numbers to LinkIDs.

Public Transport

The GIS includes information on Inter-State Bus Services, State-wide Services and District-wide Services. The main sources of information were: –

  • Directorate of Transport (responsible for regulation)
  • Interviewing private firms – mainly for Inter-State/ Tourist and the Sumo Services to extremities of the State.
  • Interviewing officials, bus/truck/jeep/van/auto-rickshaw drivers and passengers, other members of the public whilst on traffic surveys and road reconnaissance tours.
  • Meetings in Towns and Villages
  • Ad hoc meetings with PWD engineers, NGOs and members o the public in our office or at presentations.

Each State-wide service was allocated a Unique Identifier such as DML1, DML2, BSR1 where DML and BSR are the standard abbreviation of the “lines” and each District Service was allocated a Unique Identifier such as IMPL1, IMPL2 where IMP is the standard abbreviation for Imphal District and L indicates a local service. There are only two Inter-state services, which were assigned codes EXT1 – Imphal to Dimapur/Guwahati & EXT2 – Imphal to Silchar.

The whole public transport system comprises two tables – PTservices and PTroutes. PTservices contains a row for each service containing the Unique Route Identifier, the Operator, Description (e.g. Chandel to Sugnu), and Mode – bus, mini-bus, truck, jeep/gypsy, van, auto-rickshaw, sumo, and the number of vehicles plying the route per day. PTroutes contain for each stop on a route the Unique Route Identifier, the Unique LinkID of each link in the road network that the bus route serves and the sequence of that link along that route (i.e. first link, second link etc.). The Unique LinkIDs enable public transport information such as individual routes, the number and type of vehicles traversing/ servicing each link to be displayed geographically. Figure 4 shows the public transport route system using the Table containing village demographic information the accessibility (or non-accessibility) to public transport can be assessed.

Towns and Villages

The 1991 Census of India publishes eight volumes – one for each District (Imphal East & West are combined in a single volume). There are 2262 places – towns or villages. Each place has been allocated an Unique Identifier – PlaceID e.g. BSP.1V.12 where BSP is the standard district abbreviation in this case Bishnupur, 1 is the number allocated to the development block in the Bishnupur Volume, ‘V’ indicates the place has been designated a village (‘T’ indicates a Town) and 12 is the serial number allocated to the village in the appropriate census volume. The location of the villages was determined from the 1:50,000 toposheets, PWD District Maps and the maps in the Census Documents. The locations were digitized using the heads-up method with the 1:50,000 toposheets displayed on the screen.

Initially only a small number of the items of information contained in the census document were keyed into the computer. Now practically all the information has been keyed:

  • Amenities
  • Education
  • Medical
  • Drinking Water (Potable)
  • Post & Telegraph
  • Communications (Bus Stop)
  • Approach to Village (type of road construction)
  • Nearest Town & distance by road to nearest town
  • Power Supply
  • Demographic
  • Number of Residential Houses
  • Number of Households
  • Total Population (Male & Female)
  • Population in 0-6 year age group (Male & Female)
  • Scheduled Castes (Male & Female)
  • Scheduled Tribes (Male & Female)
  • Literates (Male & Female)
  • Total Main Workers (Male & Female)
  • Cultivators (Male & Female)
  • Agricultural Laborers (Male & Female)
  • Livestock, Forestry etc workers (Male & Female)
  • Mining & Quarrying workers (Male & Female)
  • Manufacturing, Processing and Repairs in Households (Male & Female)
  • Manufacturing, Processing and Repairs not in Households (Male & Female)
  • Construction (Male & Female)
  • Trade & Commerce Workers (Male & Female)
  • Transport Storage & Communications (Male & Female)
  • Other Services (Male & Female)
  • Marginal workers (Male & Female)
  • Non-workers (Male & Female)

Using the “Info” tool the census data for a specific town or village can be displayed on the screen simply by ‘clicking on’ the village.

In addition the amenity and/ or the demographic information relating to people living within say 3 km of a selected road section(s) can be readily summarized and/ or accumulated.

The villages contained in the census sometimes comprise two or more small settlements. To assist social, environment and other surveys the location of settlements within two kilometers (crow-line distance) of the center-line of road sections being evaluated in the Feasibility Study have been digitized from the 1:50,000 toposheets.

Earth Sciences

This major component owes much to Dr Arun Kumar and his GIS team in the Department of Earth Sciences, University of Manipur (MU). The co-operation between us started early in our work. We had digitized the road network from a 1:250,000-map base and MU provided us with the following vector tables (layers): –

  • Geological formation
  • Soils
  • Main Rivers
  • Waterbodies
  • Epicenters
  • Faultlines
  • Relief (250m increments)

which they had digitized from a 1:250,000 map base. Figure 5 shows the Epicenters and Faultlines overlaid by the main roads in the District of Tamenglong.

More recently we have ‘re-digitized’ the rivers using the 1:50,000 toposheets as a base.

In the Imphal Valley and the surrounding foothills we have together digitized the contours (100 m).

The locations of and information about recent landslides were obtained from PWD and supplemented by searches through past copies of the local newspapers.

– Dr Arun Kumar and his team are currently processing satellite images acquired by PCCS from IRS to prepare land-use/ land cover maps.

Raster Images

Raster images have two main roles in the GIS. The first is to provide the base mapping on the screen for heads-up digitizing and the second is to present information that is not, or not yet, available in vector form. (Photographs fall into the second category)

There are five folders of raster images in the GIS.

– Map250000 – 1:250,000 scale maps

  • Survey of India 1:250,000 scale maps of areas adjacent to Manipur available as gray scale as well as color
  • Original Blueprint with roads drawn on provided by PWD – Road Tracings – these were prepared by tracing the roads and rivers on the 1:50,000 toposheets. Additional village names from the District Maps were added.

– Satellite Photographs – obtained from IRS.

– Toposheets – 1:50,000 Topographic Map Sheets

– Various – The Development Constraint Maps (19 in all) from the “Zoning Atlas for Siting of Industries” prepared by the Central Pollution Control Board. Photographs, mostly of the roads, taken on the road observation tours. Pages from Manuals etc for use in training/ presentation.

Other

Road Accidents

Information on all road accidents in the five years 1994-1998 was prepared by the Police or the Director of Transport. Only personal injury accidents were recorded. The locations of the accidents are written descriptions. From these we were able to identify on which road link in the Road Network the accident occurred in three out of four cases. For economic assessments and to guide road safety campaigns additional data on injuries received in road accidents were obtained from the Hospital.

Historic Sites

The location of important historic sites was obtained from local literature.

Hospitals and Major Health Centers

Information on health facilities were obtained from the Dept of Health and the 1991 Census.

Acknowledgements

Without the encouragement and support of E. BinoyKumar Singh (ex-Chief Engineer, PWD), A. Nilamani (Project Director, PWD), R Riding (Team Leader) and the co-operation of Dr Arun Kumar the GIS would not be so comprehensive. Further without my Manipuri GIS Team – Tarun, Subho, Jeetu, Oken, Biswajit and Tampha, little of the above would have been possible.

*The article is written by Keith R Johnson

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