Highway planning

PART III
1. Planning surveys and interpretation
1.1. Planning surveys: studies for collecting factual data for highway planning.
It consists of the following studies:
1. Economic studies
2. Financial studies
3. Traffic or road use studies
4. Engineering studies
 Economic studies:
The details to be collected are:
i. Total population and classified distribution of different population groups based on
occupation ,income ,etc. .in each village , town or other locality and the area of settlement of
each classified in group.
ii. Trend of population growth of various population groups
iii. Agricultural and industrial products and their listing in classified groups , area wise
iv. Industrial and agricultural development diversifications if any and future trends.
v. Existing facilities with regard to communication, education,banks,hospitals,post office,
recreation facilities etc.
vi. Per capita income
 Financial studies
The details to be collected are:
i. Sources of income and estimated revenue from different types of taxation including revenue
from road transport sector.
ii. Standard of living of different population groups and the trends in changes
iii. Resources at local level ,toll taxes, vehicle registration and fines
iv. Anticipated development in the area and generated income
v. Future trends in financial aspects
 Traffic or road use studies
Traffic surveys should be carried out in the whole area and on selected routes and locations to
collect the following data:
i. Classified traffic volume in vehicles per day, annual average daily traffic ,peak and design
hourly traffic volumes
ii. Origin and destination studies based on detailed home interview method
iii. Traffic flow patterns
iv. Mass transportation facilities
v. Accidents ,their causes and cost analysis
vi. Future trends and growth in traffic volume and goods traffic ,trend in traffic pattern
vii. Growth of passenger trips and their trend in choices of modes.
 Engineering studies:
i. Topographic surveys
ii. Soil surveys
iii. Location and classification of existing roads
iv. Assessment of various other developments in the area that are likely due to proposed highway
development
v. Road life studies
vi. Special problems in drainage ,construction and maintenance of roads.
2.2.Preparation of Plans
Plan I: General area plan showing most of existing details,viz,
a) Topographical details on a contour plan showing rivers ,canals,
small streams, valley etc.
b) Existing road network and cross drainage structures
c) Towns and villages with population
d) Agricultural commercial and industrial activities
Plan II: Plan showing the distribution of population groups in accordance
with the categories made in the appropriate plan
Plan III: Plan showing the locations of places with their respective
quantities of productivity
Plan IV: Plan showing existing road network with traffic flows and desire
lines obtained from traffic volume and origin destination studies
Proposals received from different sources may also be shown in this plan.
 2.3.Interpretation of results of planning
surveys:
The data collected could be interpreted and used for the following important purposes:
a) To arrive at the optimum road network which has the maximum utility out of the several
alternate possible systems considered
b) To fix up priority of the construction projects
c) To assess the actual road use by studying traffic flow patterns
d) Based on the traffic type and intensity and the performance of existing types of pavement and
cross drainage structures, new structures may be designed using data and past experience.
e) Comparison of the areas may be obtained on the basis of their economic activities.
f) By appropriate statistical analysis the data obtained may be analysed to predict the future
trends in development of an area. This information maybe useful in future planning.
2.4.Preparation of master plan
Target road lengths: Master plan is the final plan for a study area, in India target road lengths were
fixed during first three 20 year plans:
Nagpur road plan:16km per 100 sq. km
Second 20 year road development plan: 32 km per 100 sq. km
Third 20 year plan: 82 km per 100 sq. km
 Determination of optimum road lengths:
Saturation system: In this system the optimum road length is calculated for an
area based on concept of maximum utility per unit length of road
The factors taken are:
a) Population served by the road network
b) Productivity served by the network-the productivity served may further
divides as:
i. Agricultural products and
ii. industrial products
Step i:Population units

Population Utility unit

Less than 500 0.25
500 to 1000 0.5
1001 to 2000 1.0
2001 to 5000 2.0,etc
Step ii: productivity units: the total agricultural and industrial system should be worked out.

The productivity served may be assigned appropriate values of utility units per unit weight.
For example:1000 tonnes of agricultural products may be considered equivalent to one unit.

Step iii: utility per unit length of road:

=(population units+ productivity units) divided by total road length of each system

Maximum value is considered

Example 1: An imaginary area with existing roads is shown in fig.1.there are four alternate
plan proposals P,Q,R and S with different road length by adding extra road links to the
existing roads in the area and the details of the population and products served are given
below:
Proposal Total road length, Number of towns and villages served Total agriculture and
km with population range industrial products
served, thousand tonnes
1001- 2001- 5001- >10000
2000 5000 10000
P 300 160 80 30 6 200
Q 400 200 90 60 8 270
R 500 240 110 70 10 315
S 550 248 112 73 12 335
Work out the utility per unit length of each system and indicate which system is
considered to be the optimum with maximum utility per unit length. Assume utility units
of 0.25,0.5,1.0 and 2.5 respectively for villages served with population ranges (1001-
2000),(20001-5000),(5001-10,000) and higher than 10001. The utility unit assigned to
1000 tonnes of productivity is 1.0.
Fig.1
Solution:
Road Road No of towns & villages served with Total units Utility Priority
plan length population in thousand per unit based on
proposal km length utility
1-2 2-5 5-10 >10 Population Productivit
y
P 300
Q 400
R 500
S 550
Solution:
Road Road No of towns & villages served with Total units Utility Priority
plan length population in thousand per unit based on
proposal km length utility
1-2 2-5 5-10 >10 Population Productivit
y
P 300 160×0.2 80×0.5 30×1 6×2.5 125 200 325/300 II
5 =1.083
Q 400 200×0.2 90×0.5 60×1 8×2.5 175 270 445/400 I
5 =1.112
R 500 240×0.2 110×0. 70×× 10×2.5 210 315 525/500 III
5 5 1 =1.050
S 550 248××0. 112×0. 73×1 12×2.5 221 335 556/550 IV
25 5 =1.010
It is seen that the plan proposal Q with total road length of 400 km has the maximum
utility per unit length of road
Therefore optimum road length in this area is 400 km.