Road Classification System - A Primer
By Mick
People travel everyday to work, shop and do many other chores. Everyone wants to get to their destination quickly, safely and hopefully with few traffic jams. We do not understand roads – why there are so many cars and why its always jammed up – especially when we are in a hurry! A good transportation system makes a good city.
What is a transportation system? Simply it’s the manner roads connect to each other, its geometry and the way it is aligned with reference to land use. Large cities comprises many kinds of roads, while smaller towns probably has fewer road types (categories or class).
A road system comprises a number of road classes – such as Expressways, Highways, Trunk Roads, Arterial Roads, Collector Roads, Streets, Lanes, Cul-de-sacs. Such a hierarchical classification system allows Traffic/Transportation Engineers and Town Planners to properly design roads. Each class (category) of road has certain design guidelines. These guidelines ensure safety, ease of maneuverability and therefore dictates the cost of construction.
 Trail A Trail is a walking path. These are normally found in Kampongs (linking one house to another) and hills and mountains. Campers and trekkers walk on these to access the mountains. Trails are very narrow with shrubs and tall grass on both sides of the path in open space. Trails in forest will have little or no shrubs or lalang on the sides due to the canopy blocking out sunlight to the ground. Up high hills or mountains, there is also very little lalang and even trees as the weather is colder. This is the montane or upper montane region as geographers call it. |
|
These are dirt roads, non tar. It is suitable for bicycles, motorcycles, 4-wheels, all terrain vehicles and trucks (lorries). |
 Residential Streets The roads within a residential suburb (Taman) are normally called streets (Lorong, Jalan). Normally streets allow two way traffic and are connected to other streets at each end. However, there are also streets that appear to be dead end. These are called Cul-de-sac. Cul-de-sac began as an old French hunting term and translates literally as "bottom of the bag". Its purpose is to reduce and limit access to people who have business to be there. It prevents thoroughfare thus reducing traffic and vehicle speed. Hence traffic noise is reduced, and safety increased. A similar situation exists in Commercial Centers (do not confuse with Shopping Complex). Commercial Centers comprises rows of shops. These are also called streets. And no, we do not call them Commercial Streets! Locally, these are the Jalan(s) and Lorong(s). The characteristics of streets are – low vehicle speed, sharp turns (right angle turns) and very little road shoulder. Road shoulder is the patch of grass at the edge of the road to the drain on both sides of the road. All roads have shoulders. The emergency lane is part of the road shoulder for Highways. Road shoulders purpose is to allow for service & emergency vehicle access. Road shoulders serve to increase the serviceability of the road and safety. The higher the permitted vehicle speed permitted on the road the wider the shoulder is. There is no restriction on road gradient (slope of road) and therefore line of sight. Such roads may be level or may be quite steep. There are no traffic lights. Streets are non divided. |
 Collector Roads The word Collector means to collect. This road collects traffic from all other streets. Its purpose is to channel traffic to other Collector Roads or higher class roads. Characteristics of Collectors Roads are – wider than streets, higher speed limit, divided road, little or no sharp bends and lower road gradients. These roads are usually not divided. Generally there are no traffic lights on these roads. However in very large townships (Bandar), there may be a few traffic lights due to the high traffic volume. In addition, the road may be a 4-lane dual carriageway. Due to the relative low vehicle flow rate and proximity to home/office, drivers tend to use their mobile phone more. Police frequently enforce the law regarding mobile phone usage on these roads. Red Light Cameras are usually placed on these roads too. |
Arterial Roads
The Collectors Roads in turn empties its traffic onto Arterial Roads at graded intersections (Traffic lights). A graded intersection is an intersection of two or more classes of roads. An intersection is a meeting of two or more roads (class of road irrelevant). It serves to link two or more suburbs together. There are numerous traffic lights on these roads which serve to throttle the vehicle flow rate. Sometimes you will find that a street or lane connects directly onto an Arterial Road. This should not happen in well designed transportation system! But it does! This is due to lack of enforcement, oversight, poor town planning or lack of funds. There is no traffic light too. You have to wait for ages in order to turn into the Arterial Road. This is an exception to the rule and cannot be avoided.
Arterial Roads have low road gradients, smooth bends (less than 60 degrees), allows for higher vehicle speed, 4-lane dual carriageways and have lots of intersections and traffic lights. A carriageway is a divided road. Such roads are wide, smooth in curvature and fairly straight, so drivers are always tempted to drive at higher speeds and therefore there are frequent speed traps on these roads. There are also Red Light Cameras on these roads.
Other Highways
Highways are designed to link townships together and allows for high speed travel. These roads are usually 4 or 6 land dual carriageways. Such roads may be wider (6-lanes) on some stretches and narrower (4-lanes) on other stretches. When townships are far apart and traffic flow rate is not high, 4-lane would suffice, otherwise it will be 6-lanes. The curvature is very smooth, usually less than 60 degrees. A first class Highway would have bends no more than 45 degrees. Forty-five degrees curvature requires lots of land and is very costly, so they are constructed at a compromise between 45 and 60 degrees. U-Turns are not allowed.
Major Highway
A major Highway is very much a Highway and there are no traffic lights and definitely no kampong roads can connect onto it. Connection between a Major Highway and other Highways or Arterials is by entry and exit ramps only except for Toll. There are lots of facilities along such Highways such as rest stops, petrol, food and even lodging (there is a hotel named Highway Hotel along the North-South Expressway before Melaka, and one closer to KL called the Mint Hotel). Such Highways also traverses beautiful countryside and scenic areas. In countries like Australia, USA, etc, there are lay-bys where you can park the car to take photographs of the beautiful scenery. Generally, there are no direct U-turns on these roads, but on most highway, U-turns is achieved by way of specially constructed underpass. On the NSE at the Sg Buloh exit, you can exit and then get onto the underpass and come out the opposite of the highway – essentially making a U-turn. Alternatively, U-turns can be achieved via exit and entry ramps – there are a few full Diamond interchange along the Highway to Putrajaya. You can exit the Highway via one leaf, pass the Highway below and down the opposite leaf and travel in the opposite direction. A full Diamond interchange is one where there are 2 loops one each side of the Highway. If you exit the highway on one leaf and traverse all four leafs you will end up on the same side of the Highway you originally exited from and traveling in the same direction. Just for information, a full Diamond interchange requires at least 50 acres of land!
Epilogue
Roads are categorized into class type for design purposes. Each class has a different design specification. Roads are categorized to allow a systematic approach to its design and construction. By design, some roads will have more traffic than others and therefore we require a graded interchange (traffic light) to regulate/throttle traffic flow.
Due to variance in politics, existing neighboring land use and level of funds available, certain specifications may be altered or amended to suite local requirements. In developed nations, Highways and Roads are designed with the prime objective of ensuring free flow of traffic. Each country has its own set of guidelines for roads and Town and Country Planning.
Sometimes design do not go the way as planned. When everything looks alright, a new township springs up adjacent to your taman! This has a pull effect and residents will take shortcuts via narrow residential roads to get to the shopping centers, etc. The well designed Collector and Arterial roads now seem quiet. The once peaceful residential streets now becomes a nightmare. In the end – nothing can substitute for proper intelligent town planning.
About the Author
Mick has a great deal of legal experience acting for local governments as well as state and national development companies on a broad range of local government, town planning and environmental matters. Mick also has practical experience as a town planner, having worked as a planning officer for the Brisbane City Council. He holds qualifications in Environmental Science, Urban and Regional Planning and Law.