Road
network can be laid in various patterns. These patterns in which the road
network is laid could be
1)
Rectangular
or Block pattern
2)
Radial
or Star and block Pattern
3)
Radial
or Star and Circular Pattern
4)
Radial
or Star and Grid Pattern
5)
Hexagonal
Pattern
6) Minimum Travel Pattern
1)
Rectangular
or Block pattern:
In this pattern, the whole area is divided into
rectangular blocks of plots, with streets intersecting at right angles. The
main road which passes through the center of the area should be sufficiently
wide and other branch roads may be comparatively narrow. The main road is
provided a direct approach to outside the city.
Advantages:
1)
The
rectangular plots may be further divided into small rectangular blocks for construction
of buildings placed back to back, having roads on their front.
2) In this pattern has been adopted for
the city roads.
3)
The
construction and maintenance of roads of this pattern is comparatively easier.
Limitations:
1)
This
pattern is not very much convenient because at the intersections, the vehicles
face each other.
Example:
Chandigarth has rectangular pattern
2)
Radial
or Star and block Pattern:
In
this pattern, the entire area is divided into a network of roads radiating from
the business outwardly. In between radiating main roads, the built-up area may
be planned with rectangular block.
Advantage:
1)
Reduces
level of congestion at the primary
bottleneck location.
2)
Prevents
traffic from accessing local flow routes in the direction of the event venue
that operate in favor of egress traffic flow.
3)
If
one is block then other side traffic can move.
4) Vehicles face each other less than block
pattern.
Limitations:
1)
Proves
particularly effective if two-lane ramp traffic does not have to merge at
downstream end of ramp.
2)
Safety
appurtenances such as guide rail transitions, crash attenuators, and post
support bases have not been designed to provide adequate protection at
hazardous locations from the opposite direction of travel.
Example: Chandigarth has rectangular pattern
3) Radial or Star and Circular
Pattern:
In this
system, the main radial roads radiating from central business area are
connected together with concentric roads. In these areas, boundary by adjacent
radial roads and corresponding circular roads, the built-up area is planned
with a curved block system.
Advantages:
1) At traditional intersections with stop signs
or traffic signals, some of the most common types of crashes are right-angle,
left-turn, and head-on collisions. These types of collisions can be severe
because vehicles may be traveling through the intersection at high speeds. With
circular pattern, these types of potentially serious crashes essentially are
eliminated because vehicles travel in the same direction.
2)
Installing
circular pattern in place of traffic signals can also reduce the likelihood of
rear-end crashes.
3)
Removing
the reason for drivers to speed up as they approach green lights and by
reducing abrupt stops at red lights.
4)
Because roundabouts improve the efficiency of traffic
flow, they also reduce vehicle emissions and fuel consumption.
Limitations:
1) Center lines
of roads leading to circular pattern should be properly aligned with the
central island.
2)
Approach
roads should be sufficiently curved, far enough in advance of circular pattern,
to reduce vehicle speeds of entering drivers.
3)
Islands
separating the approach and exit lanes, known as splitter islands, should
extend far enough to provide pedestrian refuge and to delineate the roundabout.
4)
Traffic
signs, pavement markings, and lighting should be adequate so that drivers are
aware that they are approaching a roundabout and that they should reduce their
travel speed.
5)
For
older drivers declines in vision, hearing, and cognitive functions, as well as
physical impairments, may affect some older adults' driving ability.
Intersections can be especially challenging for older drivers.
Examples:
 |
| Before |
 |
| After |
Intersection
with traffic signals converted to a circular pattern in Asheville, North
Carolina
4) Radial or Star and Grid
Pattern :
Change
in direction, and because street patterns are the most enduring physical
element of any layout, it could potentially contribute to systematic site
planning and, consequently, deserves a closer look. Though the network is
entirely interconnected, north-south movement becomes circuitous, indirect, and
inconvenient, making driving an unlikely choice and vividly illustrating that
interconnectedness by itself is insufficient to facilitate movement.
Advantages:
1) Keep vehicular traffic safe with a
high proportion of 3-way intersections.
2) Reduce cut-through traffic by similar
or other means.
3) Improve traffic flow in both
directions using Savannah’s cellular structure.
4) Improve land use efficiency and unit
density.
Limitations:
1) Islands separating the approach and
exit lanes, known as splitter islands, should extend far enough.
2)
Traffic
signs, pavement markings, and lighting should be adequate so that drivers are
aware that they should reduce their travel speed.
Examples:
The Nagpur road plan formulae were
prepared on the assumption of Grid pattern.
5) Hexagonal Pattern :
In this pattern, the entire area is provided with a
network of roads formatting hexagonal figures. At each corner of the hexagon,
three roads meet the built-up area boundary by the sides of the hexagons is
further divided in suitable sizes.
Advantages:
1) Three roads meet the built-up area
boundary by the sides of the hexagons.
Limitations:
1)
Traffic
signs, pavement markings, and lighting should be adequate so that drivers are
aware that they should reduce their travel speed.
6) Minimum Travel Pattern :
In
this road pattern, city is contented by sector center, suburban center and
neighborhood center by the road which required minimum to connect the city center.
Legend:
City center – encircled dot- sector center - * suburban center - * neighborhood center - * representation of a
Minimum Travel city
Advantages:
1)
these
types of potentially serious crashes essentially are eliminated.
Limitations:
1)
Traffic
signs, pavement markings, and lighting should be adequate so that drivers are
aware that they should reduce their travel speed.
2)
Intersections
can be especially challenging for older drivers.
