INTERSECTIONS & ITS TYPES: - At
the intersection there are through, turning and crossing traffic and these
traffic movements may be handled in different ways depending on the type of
intersection and its design. Intersection may be divided into two groups:
[1]
Intersection at grade: - These
include all roads which meet at more or less the same level. The traffic
maneuvers like merging, diverging and crossing are involved in intersection at
grade. These intersections may be further classified into Unchannelized,
channelized and rotary intersections.
(i) Channalized intersection: -Channelized intersection provides
more safety and efficiency. It reduces the number of possible conflicts by
reducing the area of conflicts available in the carriageway.
(ii) Unchannalized Intersection: - The
intersection area is paved and there is absolutely no restriction to vehicles
to use any part of intersection area. Hence the unchannalized intersections are
the lowest class of intersection, easiest in the design.
(iii)
Rotary Intersection: -
Rotary Rotary intersections or
round abouts are special form of at-grade intersections laid out for the
movement of traffic in one direction around a central traffic island.
[2] Grade separate intersections: - Grade separated intersection design is
the highest form of intersection treatment. This type of intersection causes
least delay and hazard to the crossing traffic and in general is much superior
to intersection at grade from the point of view of traffic safety and efficient
operation.
CAUSES
OF ACCIDENTS: - Various causes of accidents may hence
be listed as given below:
(1)Drivers: - Excessive speed and rash driving,
carelessness, violation of rules and regulations, failure to see or understand
the traffic situation, sign or signal, sleep or alcohol.
(2) Pedestrians: - Violating regulations, carelessness in
using the carriageway meant for vehicular traffic.
(3)Vehicle defects: - Failure of brakes, steering system, or
lighting system, tyre burst and any other defect in the vehicles.
(4)Passenger: - A lighting from or getting into moving
vehicles.
(5)Road Condition: - Slippery or skidding road surface, pot
holes, ruts and other damaged conditions of the road surface.
(6)Road Design: - Defective geometric design like
inadequate sight distance, inadequate width of shoulders, improper curve
design, improper lighting and improper traffic control devices.
(7)Weather: - Unfavourable weather condition like,
mist, fog, snow, dust, smoke or heavy rainfall which restrict normal visibility
and render driving unsafe.
(8)Animals: - Stray animals on the road.
(9)Other Causes: - Incorrect signs or signals, gate of
level crossing not closed when required, ribbon development, badly located
advertisement boards or service station etc.
TYPES
OF ACCIDENTS: - Road traffic collisions generally fall into one of four common types:
[A] Lane departure
crashes, which occur when a driver leaves the lane they are in and collide with
another vehicle or a roadside object. These include head on collisions and run-off-road
collisions.
[B] Collisions at
junctions include rear-end
collision and angle or side
impacts.
[C] Collisions
involving pedestrians and cyclists.
[D] Collisions with
animals.
[E] A moving vehicle collides with a parked vehicle.
[F] Two vehicles approaching from different directions
collide at an intersection.
[G] Head on collision of two vehicles approaching from
opposite directions.
[H] A moving vehicle collides with a stationary object
like an electric pole, tree or a rigid structure.
METHODS
OF PREVENTION OF ACCIDENTS: - To prevent or minimize accidents, the road engineer,
the road user and the legal authorities will have to go hand in hand. The road
engineer will design the pavement in such a way so as to minimize all possible
chances of accidents by providing the following facilities to pedestrians and
vehicular traffic:
1.
Providing traffic signal
for pedestrians.
2.
Installation of
pedestrian in islands.
3.
Improving street
lighting.
4.
Construction of under and
over bridges where essential.
5.
Proper design and marking
of cross walks.
6.
Efficient layout of
crossings, junctions and corners.
7.
Providing proper cross
section of road.
8.
Providing suitable super
elevation and transition curves at all curves.
9.
Provision of non skid and
uniform surface.
10.Providing traffic segregation where possible.
The road users should realize their
responsibilities towards each other. A road user must realize the difference in
speed between the pedestrian and vehicular traffic especially pneumatic
traffic.