Here is how speed limits are set

Thursday June 27 2019

When you are about to drive into a busy trading

When you are about to drive into a busy trading centre, a speed limit sign will be erected such as this one on Ishaka-Kagamba road. Photo by Abubaker Lubowa. 

By Roland D. Nasasira

Different Ugandan roads have different speed limits. While there are motorists who actually observe these limits, there is also a category of those that do not.
Kenneth Sunday Kasenene, a road safety officer with the Ministry of Works and Transport, says speed limits are road design aspects. Technically, speed limits are also known as design speeds. As such, a number of factors determine what speed limit you drive along certain roads.
“A speed limit is a warning and an assignment to watch your driving speed. When you see one that reads 50km per hour, it is a warning that you will meet something such as a junction or curve ahead. It is a warning that you must not drive above 50km per hour,” Kasenene warns.

Overtaking sight distance
Your car speed pickup is one of the most important aspects that Charles Ssebambulidde, the spokesperson of the traffic directorate, warns you should be sure of before overtaking. Besides car speed-pickup, other important overtaking aspects you must understand include the distance within which you are overtaking and the speed of the oncoming vehicle on the opposite side.
“While the overtaking distance may appear to be long, you need to understand the rate at which your vehicle picks up speed from the onset of stepping on the accelerator. You do not wish to overtake and get stuck somewhere. This might end up causing a head-on collision or a crush between two vehicles because your car did not pick up speed and you were not successful in overtaking,” Ssebambulidde advises.

Curves
Curves along certain road, especially along highways determine your driving speed. These, according to Kasenene, are classified into vertical and horizontal curves. They can either be in form of corners where you do not see what is ahead of you, or curves where you see where you are driving to at a distance but have to drive down and up the hill through valleys.

Terrain of the area
When driving in hilly areas such as Kabale, Ntoroko, Kyenjojo, Kapchorwa and Kisoro, it will be natural that you drive within a certain speed as indicated on speed limit signs compared to smooth terrains such as Gulu Road. This is because roads in these places were constructed along degrading hills to attain a certain level. This, therefore, involves limiting the speed at which you drive in such areas.

Road environment
According to Kasenene, the environment of the road is mostly in terms of its width. It also includes the number of lanes on the outgoing and oncoming traffic and vehicle interaction on both sides. For example, while Jinja to Kakira is a four-lane road (two lanes both incoming and outgoing traffic), Jinja to Malaba Road is a two-lane road because of its high traffic volume.
“If it is a one way road, it will be assigned higher speeds since all vehicles are facing and moving towards the same direction. If it is a double lane road, the speed limit will be low because not all vehicles are moving in the same direction,” Kasenene clarifies.

Type of road
In Uganda, road types are categorised into expressways, two lane roads as well as rural and urban roads. With urban roads, speed limits are normally low because of heavy traffic movement. However, roads such as Jinja Road from the Wampewo Avenue roundabout to Nakawa may have been constructed to allow fast driving but the speed limit gives you an assignment to keep within a prescribed speed because of high traffic and junctions.
With rural roads, they are always characterised with low traffic. In this case, they are sometimes assigned higher speeds except at trading centres that have a lot of pedestrian movements. Here, you are assigned low driving speeds.

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Junctions
Junctions are in most cases unknown and hard to identify, especially along roads you are not familiar with. According to Kasenene, it is at this point that speed limits weigh in to alert you.
“Assignment of speed limit goes with safe stopping so that by the time you see a speed limit sign, you have ample time to reduce speed,” Kasenene explains.

Features of the road
Some of the features used to determine speed limits include junctions, roundabouts and signposts.
“By the time you interact with a sign post, there is a provision of how further you can drive before stopping,” Kasenene says. Other factors that determine speed limits include the condition and the class of a particular road. This is because some roads have design speeds of 80km/hour but can go up to 100km/hour depending on its classification.

The speeds
According to the Uganda Highway Code 2006, if you are driving at 30km/hour, you can be able to stop your car in 12 metres, which is a three car length. If you are driving at 50km/h, you are able to stop the car within 23 metres, which is approximately a six car length. If you are driving at 80km/h, you are able to stop the car within a 53 metres distance, which is equivalent to a 13 car length, while you will be able to stop your car within 73 metres or an 18 car length if you are driving at 100km/hour, all after interacting with a speed limit.

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