Speed limit for the Southern Highway
Ananda RANASINGHE
The construction of the Southern Highway has made a significant
change to our road network system. We never dreamt of having a dual
carriage highway in Sri Lanka at least for the next decade. However,
with the change in the government along with the resulting end to the
ongoing conflict, a vast development programme has taken place with the
prominent Southern Highway project taking pride of place.
However, I am quite sure that our drivers are not used to driving on
a highway as we still have people who continue to drive on the right
side of the road instead of the left. Quite often cyclists have taken it
for granted that they could ride any way they like even on a highway.
Sometimes I have noticed people doing these mistakes even in the
presence of traffic police who do not take serious note of such
violations.
Although covering trucks or lorries when carrying loads is mandatory
in public highways, this has been done merely as a camouflage by such
vehicle owners, whereas these do not safeguard the rights of pedestrians
and other road users.
Southern Highway to spur development |
Road users
A few decades ago the Police were very serious about stray cattle on
the roads and quite correctly this is a serious threat for the safety of
road users. I have come across situations where even within the town
limits stray cattle are a common sight on the streets. Such type of
obstacle can be a potential death trap in a high-speed highway. I am not
certain as to what measures have been taken on the Southern Highway to
prevent stray cattle from entering the roadway.
I have also been made aware that the speed limit in the Southern
Highway has been set at 120 KMPH. This is rather a high speed limit
where the braking distance might be a few metres. Therefore by the time
one reacts to an emergency one may have travelled a long distance and
the repercussions of this travelling distance could be quite disastrous.
Most traffic engineers believe that speed limits should be posted to
reflect the maximum speed considered to be safe and reasonable by the
majority of drivers using the roadway under favourable conditions.
Procedures used to set speed limits have evolved through years of
experience and research. Most countries set safe and reasonable maximum
speed limits based on the results of an engineering and traffic
investigation. At the same time, the engineers use the 85th percentile
speed as a major factor in selecting the appropriate speed limit for a
given street or highway, other factors such as roadside development,
accident experience and design speed are often subjectively considered.
Fixing speed limits
The 85th percentile is a major parameter used by traffic engineers
and transport planners and is defined as: “The speed at or below which
85 percent of all vehicles are observed to travel under free flowing
conditions past a nominated points.” Free Flowing is defined as: “A
vehicle is considered to be under free flowing conditions when the
preceding vehicle has at least four seconds headway.” Therefore a
detailed study has to be done before fixing speed limits and it
shouldn’t be an arbitrary decision of an individual.
Our drivers still have the habit of stopping or slowing down at the
centre of the lane without any warning, using signals improperly when
overtaking, sight-seeing when travelling, using cell-phones while
driving, not wearing seat belts, overloading etc. Some vehicles even
with damaged lights still continue to be driven on public roads. Their
tyres are not tested and they may not be good enough for driving at high
speeds. All these add up to serious accidents on public highways. Sri
Lanka has a death rate of six persons per day on highways. Therefore it
could have been much better had we started the speed limit from about 85
KMPH and observed the accident rate before increasing the speed limit up
to 120 KMPH which is extremely high even on a highway especially for Sri
Lanka.
Road construction
The commencement point of the Southern Highway according to the
information available is somewhere around the Kottawa area. Therefore,
link roads leading to Kottawa have to be done in order to gain the
maximum benefit of this highway. Presently, the Old Kottawa Road is
being widened in order to take more traffic. This should have been done
at the commencement of the construction of the Southern Highway.
Widening involves not only road construction, but there are a lot of
additional work that has to be done. For e.g. service lines have to be
laid or shifted to the side of the road.
In some countries they provide a separate area parallel to the new
road in order to lay the service lines to minimize damage to the new
highway. It is also important that at suitable intervals ducts or pipes
have to be laid in order to connect the services from one side of the
road to the other. Therefore proper planning has to be done before
commencement of any roadwork.
Expediting work during the day and night is a good thing but it does
not mean that one should do planning hurriedly or ignore proper
planning. In most of the major roads or road widening projects that have
already been constructed, there is the problem of maintaining services
or introduction of new services as no solutions had been made for this
purpose at the planning stage.
Shifting a water line, or for that purpose a telecommunication cable,
is extremely expensive and time consuming. The author has experienced by
his work abroad that cables have sometime to be ordered or fabricated as
telecommunication cables are not readily available in the market and
therefore roadwork might have to be interrupted for a few months until
the cables are relocated. This emphasizes the importance of planning a
project, and at the same time it is also important that once the design
work is done it has to be studied by experienced engineers since quite
often designs are done by junior engineers.
Dangerous intersection
A good example of this is the roundabout at Parliament Road near the
‘Water’s Edge Hotel’ intersection. Although the earlier road was not as
wide as the present one it had a user-friendly roundabout by which to
negotiate and travel safely. After reconstruction however, the
roundabout has now been replaced by a sharp bend which acts as a
bottleneck, thereby causing a situation where vehicles coming from both
directions have to face each other thus creating a dangerous
intersection. As a result of this it has now become always necessary for
a Police Constable to direct vehicles at this intersection. This shows
that road improvements can also be counter productive if no proper
planning has been done.
The author has also observed road widening being carried out at the
High Level Road which is an access road to the Southern Highway. This
may involve relocation of a substantial amount of services such as
electricity, water, telephone lines etc. These relocations cannot be
done overnight and it might sometimes take a few years. Therefore, it
would have been much better had such relocations been commenced at least
a few years back.
Sometimes, for planners it is just a matter of calling for a
relocation of a water line but for a water supply engineer this could
mean a major job where planning has to be done with pipes and other
fittings that need to be imported, maintenance of existing services
while the line is being relocated, land acquisition, preventing
disruption to other existing services, etc. Therefore, when widening a
road the highway engineer has to allow for all these eventualities. Once
a retaining wall is constructed at exorbitant cost it cannot be
relocated for further widening.
Therefore any structure that a highway engineer builds on the road
has to be well thought out. While highway engineers were constructing
the intersection in front of Water's Edge, as a driver who used this
road quite often I am sure I have not been alone in observing that there
was something wrong with the planning of this intersection.
I have also observed that a massive retaining wall is being built in
front of the Dharmapala College on the High Level Road. Once such
structures are built, widening of the road is restricted as one could
widen only up to the retaining wall. Therefore when taking such
decisions one has to look into the necessary width of the road and the
requirements for future expansion etc. Also, when spending money on such
work utmost care should be taken before construction commences. There
are many multi-billion Rupee projects which have been constructed which
people still believe have been done at the wrong locations.
Since Sri Lanka drivers are not used to driving in lanes or are not
bothered to drive within a lane, this attitude could be quite dangerous
for people driving on a highway at very high speeds. Overtaking is also
done in a very haphazard manner and on many occasions these traffic
violations continue without being penalized by the authority. Flashing
lights and taking right turns are very common practices used by some of
the drivers. There is no such signal in the highway code. However, some
drivers think that they could violate any rule by merely flashing their
lights at an oncoming vehicle. Therefore drivers have to be disciplined
before they are expected to observe very high speed limits. I have seen
recently in many locations on the public highways where there are
damages at the centre of the road into which a passer-by with good
intention may plant a branch of a tree in order to warn road users of
impending danger. However, if there is a potential danger due to the
failure of the roads, such area should be immediately cordoned off by
the authorities and illuminated especially at night.
Sadly this does not happen often enough either due to ignorance or
they have less value for human life.
The above practices indicate that we are still far away from applying
speed limits of well over 100 KMPH in our highways.
The authorities who fix these speed limits may have not gone deep
enough into the statistics to evaluate how dangerous these speeds can be
to travellers. Therefore, I believe that a fair amount of study has
still to be done before extending our speed limit to more than 85 KMPH.
The writer is the President-Elect, Institution of Engineers, Sri
Lanka |