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Log In Sign Up. Lee Sheng Yew. This issue omits the Chapter on Specification and Bill of Quantities which was included in the earlier publication and the guardrail specification is now incorporated into the Standard Specifications for Road Works. Departmental policy on guardrail installation has been included in this issue. This Arahan Teknik will be continually updated from time to time and in this respect any feedback from users will be most welcomed.
Traffic barriers are highway appurtenances that provide a relative There is a need to provide highway design degree of protection to vehicle occupants engineers with a choice of safe and effective from hazardous roadside features and from guardrail and medium barrier systems.
The errant vehicles encroaching across a application of traffic barriers should result in median. However, guardrails have sometimes been misused, perhaps due to a ii. Traffic barriers are classified into two misconception of their function. Guardrails are basic groups according to functions: not installed to protect roadside objects or prevent accident occurance, but to protect a Longitudinal vehicle occupants from possible serious injury.
Longitudinal traffic barriers perform Therefore, if a guardrail is to be installed, the by redirecting errant vehicles away engineer must be satisfied that the severity of from the roadside hazard.
This document only covers Longitudinal traffic barriers. The purpose of this document is to give some introduction on the several types of traffic 1. Highway traffic review of existing installations. Sound barrier installations on shoulders prevent application of these considerations will facili- vehicles access to steep embankments or fixed tate the provision of appropriate traffic barriers objects, whereas median barriers are used to ensure roadsides incorporate a consistent and between the roadways of divided highways to economic degree of safety.
Types of barrier not described may be developed, or be found in use in other Barrier installations are therefore warranted countries. However, they should not be adopted or justified only at highway locations where within Malaysia without careful identification the consequence of an errant vehicle leaving of critical design features, investigation of the roadway is judged to be more hazardous performance records or preliminary testing.
Semi-rigid Barriers which are used where thousand vehicles leave the highway at a point. It can be classified into two Hence accident frequency is not a principal groups: factor in determining barrier warrants. For this reason,the highway designer performance is independent of impact point should make every effort to design without at or between posts and of soil properties, guardrail. This can be done by and 2 vehicle snagging on a post is virtually eliminated.
Flexible Barriers which relies on large b providing adequate clearances to dynamic deflections to redirect errant structures; vehicles gradually. It may be necessary to consider the The flexible barrier system is the multiple provision of safety barriers where the above wire rope beam mounted via measures cannot be applied or are offset brackets to post. Tests have shown considered impracticable. Rigid Barriers which are normally used where lateral deflections are not permitted,such as locations at narrow medians.
As hese systems must be essentially unyielding, they are almost exclusively constructed of massive sections of concrete. Roadways on high embankment and follows: embankment with steep side slopes, i. Establish "point of need" or "length of ii.
On highways with roadside obstacles and need" by warranting consideration as in hazards such as structures and sub-section 2. Based on the unobstructed space available iii.
Divided highways with narrow medians, for system deflection, select a barrier carrying large volume of traffic, system as in sub-section 2. For bridge rail selection, the system must be iv. Other conditions such as sharp horizontal structurally compatible with the bridge. Determine design particulars for the selected system, such as terminal The three principal features are A slopes treatments and adjustments for highway embankment, B roadside obstacles, and C curvature.
Other factors are iv. Make installation layout drawings. Note dependent on site conditions, traffic character- that for guardrails and median barriers, istics and accident experiences installations should be extended to a which are considered individually.
A method for establishing this necessary extension is Height and slope of roadway embankments presented in sub-section 2. For low, flat v.
Make a field review, near the completion embankments, out of control vehicles can "ride of highway construction, before setting the out" a slope with a hazard less than that final installation limits. Short gaps associated with striking a barrier. For high, between installations should be avoided. A dividing line between these extremes is as Traffic barrier warrants are decision criteria shown in Figure 2. This curve is independent that identify sites along highway needing traffic of accident frequency and embankment slope barrier installations.
These warrants are delin- material. Warranting criteria presented below have been developed from analysis of run-off-the-road accident statistics and are applicable to highways in general. If the 10m zone cannot j street lighting poles, be cleared of roadside obstacles such as bridge piers or permanent buildings, due to practical k railway tracks.
As most of these hazards extend a consider able length along the roadway, the probability Examples of roadside hazards that warrant of errant vehicles striking the hazards is higher. If this is not possible,traffic barriers b large boulders, are to be installed. When guardrails are used on embankments along shoulders they should be c permanent bodies of water with placed at a minimum distance of 1.
Warrants for these barriers are determined by median width and the averaged i. The obstructed space available for lateral daily traffic volume. The median barrier need deflection or maximum desired deflection can be determined as shown in Figure 2.
It is for a guardrail, suggested that this daily traffic volume be based on a 2-year projection. Median barriers ii. The roadway or bridge structure are not warranted if median width exceeds 15 cross-section, and metres except on the basis of adverse accident experience.
It is noted that although accident iii. The installation and maintenance costs. Deflection, an important characteristics of a system to the space system characteristic, is the maximum lateral available at the highway site. For the systems deflection that a system experiences during to perform in a similar manner in actual impact and redirection of a selected vehicle.
Where barriers can cause errant vehicles to vault a barrier or to are installed on superelevated sections of strike it so that the vehicle overturns. Optimum highway, the vertical axis of the barrier should barrier system performance is provided by a be inclined in order to remain perpendicular to level surface in front of the barrier. Preferably, the pavement surface. This is particularly face of barrier should be aligned above the face important for slope-face.
This is particularly of kerb; if however kerbs must be in front of important for slope-face concrete barriers. However, cost of vehicle damage is higher for 4 interaction of the barrier or supports more rigid system. If two or more guardrail with any subsurface rock, services, systems satisfy lateral deflection requirements, or drainage structures or with surface final system selection can be made on the basis drainage paths, and of: 5 ease and frequency of maintenance and repair including effects on traffic operations.
It is not necessary encroachment distance. Height of rail with respect to local grade is held constant. A Short sections of guardrail' should be avoided minimum offset of 1. An isolated length of guardrail 3 metres should be used.
The flare should be on an embankment should not be less than 30 gradual to flatten the angle of impact by metres. For high speed facilities, a minimum of vehicles leaving the road. As a guide, the 75 metres is desirable. Short length of guardrail length of flare, should not be less than ten is only useful as a warning of the presence of times the offset obstruction or hazard but is inadequate as a physical protection.
The beam may be employed, a typical installation is composed of twisted 90 within the ramp section and is three components: generally anchored at-grade to a concrete footing. To prevent an errant vehicle from striking the warranting feature, the installation must be extended a considerable distance upstream.
Furthermore, terminal sections must be added to both ends to anchor the system in order that redirecting force can develop in the rail. There are three general types of guardrail terminal treatments: i. However, for economic consideration and ease of maintenance, standard systems are adopted 2. Rigid guardrail adopts the New consideration and an improper designed end Jersey design as shown in Figure 2. Guardrail ends must be strengthened to prevent excessive ii.
Semirigid guardrail follows the existing deflection and the possibility of the rail end practice of corrugated sheet steel beam penetrating the vehicle occupant compartment.
In rural areas, timber posts of launch an errant vehicle and the flare increases either Chengal or Berlian can be used. To remove this danger, the approach ends must be anchored to iii. For terminal sections, flared terminal the ground to give the needed stability to treatment is used. In case where space is adjoining sections and should be flared well not available, ramped terminal can be away from the travelled way to prevent used.
Straight extension terminal is used vehicles from striking the anchored ends with a only where terminal is pointing away resulting over-ride or roll-over. If the approach from one directional traffic flow.
Return ends are not flared back, then they should be section terminal is used at narrow blended into the approach environment. On approaches to structures, the guardrail must be securely attached to the structure in order to give maximum protection and to develop full strength of the rail in tension and provide a relatively smooth configuration on the traffic side. For all new semi-rigid guardrail installations,corrugated sheet steel beam 3.
Timber posts may be used on rural roads of R3 standard and below. The timber The corrugated sheet steel beam guardrail posts shall be of heavy hardwood only of commonly used consists of sheet steel beam of either Chengal or Bilian. W-shape cross-section attached to block-outs or spacers supported on posts.
Arahan Teknik (Jalan) 2C-85 - Temporary Signs and Zones Control
P R E F A CE The purpose of this manual is to establish uniformity in design and application of all traffic signs and control devices in Malaysia for the benefit of road users, road and traffic authorities, and manufacturers of traffic signs. The Manual is now divided into the following parts: 1. Standard traffic signs drawings for Regulatory, Warning and Guide signs are illustrated complete with dimensions. A color chart for all the traffic signs indicates acceptable colors for each sign.
Arahan Teknik (Jalan) 2A-85 - Standard Traffic Signs
The Manual is now divided into the following parts Standard traffic signs drawings for Regulatgry, Warning and Guide signs are illustrated complete with dimensions. A colored chart for all the traffic signs indicated acceptable colors for each sign. It consists of, with the exception of Temporary signs, design cri teria and location requirements for all traffic signs. It consists of standard temporary sign drawings and their application in the work zones. Standard road line paints, road markings and delineators are identified together with guides on their applications.