Well, our country has a challenging geological construction. for example, if you look at the capital itself, the roads have mostly 4 lanes.2 on each side. the vehicles are overcrowded and especially nowadays the sale of the 4 wheel drive has increased.
traffic signals are the way to manage the flow of traffic. first of all the cost of it is too high, and the other thing is the maintenance of the signal, as it is run 24 by 7 days a week. the roads are not equipped to handle so much of the traffic.
I remember once there was a signal for the pedestrians to cross the road, but the traffic police himself let them cross the road before the timer has even stopped. upon asking him then what is the use of the signal he simply replied that pedestrians are being chocked by the dust. in the capital, there are signals installed in most areas, but as I said due to the limited lane it was not working for the smooth flow, rather it did the opposite. since then the government hasn’t worked on installing more but rather they have deployed more traffic officers in most of the junctions.
My suggestion would be to add these signals in the terai region rather than the hilly region. the roads of the terai area are broader and they won’t face the bottleneck issue.
until the government doesn’t find other solutions to more traffic congestion, the manual will be the best option. one idea would be having overhead bridges in the major junctions than investing in the pedestrian overhead bridge, and also people have to be educated much more about the safety of the driving. mostly in the capital people always tend to be in a rush. they squeeze two wheeler s in every possible entrance as possible just to be ahead.
I myself travel 7 km in a two-wheeler one way to the work and there are two major areas I have to come across where the possibility of being stuck in the jam.
The traffic signal is programmed in certain times but if done manually by the traffic police he uses his common sense as the cases might be of two way are jammed packed and the other two way has the neutral traffic, the signal will work as it is, even though there are any vehicles left to pass by where as the other two’s time s not enough to clear up the jam.
There might be many other reasons as well but this is my own personal experience I am telling you.