Page 1 of 8 CJ Technical Updates - Issue No. 1 (1/2016)

JKR 20400-0102-16 Website: http://www.jkr.gov.my ISSN 2231-7988

Issue No.

1 1/2016

Theme of the month:

Development of Design Guidelines for Emergency Escape Ramp

Cawangan

Jalan

CJ Technical Updates Bulletin on lessons learnt in:

Road Safety

BACKGROUND On the 21st of August 2013, Malaysia recorded the worst ever single vehicle accident in the history of motoring in the country. Thirty-seven (37) people died and sixteen (16) others were injured when a daily bus on a routine trip back from Genting Highland plunged about 60m down into a ravine. The runaway bus failed to take advantage of an emergency escape ramp prior to the location where the incident took place. An existing rubble pitching wall that was supposed to stop the vehicle in time was also smashed into pieces. Much hype was circulated among the public as to the cause of the crash. Among it were the driver’s driving attitude, vehicle brake failure and the installation of the wrong type of barrier. With a quite comfortable road width, the bus was said to be travelling at high speed downhill along a very winding road alignment. Prior to the final lap is an emergency ramp that had been constructed to be utilised by runaway vehicles which, unfortunately, was not taken advantage of in the crash. Questions were raised regarding some of the engineering aspects of the ramp especially the appropriateness of the siting and some features of the ramp.

Fig. 1: The horrific Genting Highland bus crash on 21st August 2013 The lack of relevant references has prompted Cawangan Jalan JKR to look into the development of a technical guideline on the design of emergency escape ramps. This paper presents a technical update on issues relating to the causes of road crashes due to runaway vehicles and some pertinent points in the development of the guideline.

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REVIEWING THE PROBLEMS In the development of appropriate measures to alleviate the potential risk of crash due to runaway vehicles, it is important to identify and understand the possible causes of such crashes. Each cause should be examined and evaluated before proposing suitable countermeasures. The causes of road crashes due to runaway vehicles can be attributed to three common known factors namely:

a. Human factor The capability of drivers to control their vehicle during the descent is of paramount importance. Any misjudgment in speed may risk in losing control on the long steep downgrades. Inability of drivers to control vehicle speeds on downgrades is not only hazardous but it can also have costly consequences, ending up in ravines or crashing onto slopes or populated built up areas. Drivers must always know the current condition and fitness of their vehicles before and during any journey. Apart from having some knowledge about vehicles, drivers must also know how to operate and control their vehicles in different road conditions. The need is more critical when travelling on roads situated in mountainous terrain especially during long downward descent. Equally required are guidance and facilities for drivers travelling on such roads which are the responsibilities of the road authority.

b. Vehicle factor

Heavy commercial vehicles and long haul transport buses need special attention particularly when travelling on roads in rolling and mountainous terrain due to the risk of losing control on these long steep downgrades. Apart from their physical and mechanical fitness, safety aspects relating to gear and braking system are also equally important. During a long descent, there will be a continuous use of braking and gear control. The prolonged use of braking may develop excessive heating on the brake system that usually ensues in a phenomenon known as brake fading. Brake fade is a term used to describe the partial or total loss of braking power due to high temperature generated during braking which can happen on motorcycles, cars, buses and heavy commercial vehicles.

c. Road engineering factor

Roads through rolling and mountainous terrain are sometimes designed under constrained circumstances which results in adverse road geometric features. Among such features is the design of substandard vertical profiles featuring long steep downgrades that may present serious mechanical problems mainly to heavy commercial vehicles including buses.

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MITIGATING MEASURES The adverse effects of the factors above need to be addressed or at the very least reduced in order to improve the safety features of the road section in question, particularly long downgrade sections. If all these fail, the final mitigating measure at the last few seconds before a crash happens may be necessary, i.e. the emergency escape ramp. It can be generally concluded that improvements on safety on long downgrade sections of a road can be categorised into the following:

a. Installation of warning and guide signs Before entering the downgrade section, drivers shall be presented with a number of advance warning signs including distances to related facilities. This is to allow drivers to make preparation mentally and also physically.

b. Construction of relevant facilities

Existing roads usually lack some of the important facilities before drivers enter the downgrade section such as the brake check and rest areas. These areas are basically parking space for vehicles to allow drivers to conduct a final check on their vehicles before making the descent. It also allows the brake system to cool down after making the previous descent.

c. Construction of escape ramp At the final seconds before a crash, a runaway vehicle needs a special exit facility to enable the vehicle to reduce its speed and regain control without causing serious casualties or affect other road users. The facility is a special ramp that needs to be properly located and adequately designed to ensure that it can be used effectively. Sufficient ramp length and correct entry alignment enhanced with suitable alerting feature, are some of the design elements of an emergency escape ramp including the use of proper arrester bed material and containment features.

The above transcriptions are generally the basis in the development of the guideline on the design of emergency escape ramp. More detailed explanations are given in the guideline document. DESIGNING THE RAMP

The main highlight of the document is the design of the emergency escape ramp. It covers every aspect of the escape ramp elements including the maintenance requirement for the ramp to continuously operate effectively. The outline of the guideline covering the design of emergency escape ramp is described as follows:

1. Types of ramps: gravity escape ramps, arrester bed (descending grade, horizontal grade and ascending grade), sand pile escape ramps and mechanical arrestor escape ramp

2. Determination of need: sequential decision approach such as review signs, provide brake inspection area, install emergency escape ramps and banning of selected vehicles

3. Design consideration: location, signing and marking, supplemental features such as brake inspection and rest areas, variable message sign and misuse of escape ramps

4. Emergency escape ramp design: ramp alignment, approach to ramp, ramp grades, ramp length, ramp width, attenuation and side barrier

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5. Ramp structure: layout for escape ramp, arrester bed material, bed material depth and drainage

6. Design process: Fig. 2 shows the steps involved in the escape ramps design process. 7. Maintenance of Escape Ramp:

a. It is essential that the aggregate bed be reshaped as soon as possible after a vehicle has been removed from the gravel.

b. The gravel should be loosened up/scarified after each use of ramp/every six (6) months, whichever occurs more frequently.

c. Another indicator that the aggregate is becoming contaminated is when the vehicles using the ramp travel increasing distances along the ramp.

d. After each use, the single size aggregates at the escape ramp should be reshaped using manual means to the extent where possible and the aggregates scarified as necessary.

Fig. 2: Escape Ramps Design Process

S1: Identify suitable location of ramp

S2: Determine the vehicle entry speed

S3: Design entry alignment

S4: Determine the types of facility

S5: Determine the pavement surface of the facility

S6: Design facility length

S7: Design the facility

S8: Design end treatment

S9: Design delineation

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PILOT PROJECT During the development of the guideline, JKR was given the task to identify locations throughout the country where escape ramp facilities are required. The first project was located at Section 10, F0185 Jalan Aring – Kenyir - Kuala Jeneris, Hulu Terengganu, Terengganu. This existing road has a gradient of more than 10% with a 30 m deep ravine on one side and has recorded quite a number of crashes due to runaway heavy vehicles. In 2014, with the cooperation of Road Facilities Maintenance Branch, the project was constructed by Roadcare Sdn. Bhd under the supervision of the District JKR. Roadcare Sdn. Bhd. is the maintenance concessionaire for the eastern zone of Peninsular Malaysia. The type of escape ramp that was constructed is a 7 m wide by 80 m long ramp consisting of 450 mm thick arrester bed on a descending grade while the length of the approach to ramp is 50.5 m long. 40 mm single size aggregates are used as the arrester bed material to provide sufficient drag for the runaway vehicle. To protect vehicles from falling at the side, a concrete barrier with a height of 1.5 m was also constructed. The end of the ramp is closed with W-beam guardrail which also acts as a low attenuation device to stop any vehicle that may travel beyond the length of the ramp. Summary of the ramp design parameters are given in Table 1. According to the information from the District JKR and maintenance concessionaire, there have been more than ten (10) incidences of runaway heavy vehicles experiencing brake problems using the ramp since its completion in 2014. Therefore, it can be concluded that the construction of the escape ramp at the location is proven to be a right decision. It has also successfully avoided serious mishaps and has worked seamlessly effective. It should be noted that the escape ramp seems to work well even though the design of the ramp does not fully meet all of the required design criteria.

Fig. 3: Pilot Project Section 10, F0185 Jalan Aring-Kenyir-Kuala Jeneris, Hulu Terengganu,

Terengganu

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CONCLUSION The development of the guideline on the design of emergency escape ramp has been quite an interesting experience where the implementation can be seen from theory into practice. Successful implementations of such facilities are highly dependent on the appropriate location of the site for the escape ramp where many lives can be saved.

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Table 1: Escape Ramps Design Parameters

Types

Gravity escape ramps Arrester bed Sand pile escape ramps Mechanical arrester escape ramps

Ramp alignment ≤ 5°

Approach to ramp ≥ 150 m

Ramp grades

Bedding material

Portland cement concrete Asphalt concrete Gravel, compacted Earth, sandy, loose Crushed aggregate, loose Gravel, loose

Entering Speed (km/h) 130 - 140 𝑉𝑓2 = 𝑉𝑖

2 − 254 𝐿 (𝑅 ± 𝐺)

Ramp length

𝐿 = 𝑉2

254 (𝑅 − 𝐺)

Ramp width ≥ 8 m

Attenuation Crash cushion Wire rope Granular-filled barrel

Side barrier ≥ TL4

Arrester bed material 40 mm is recommended

Bed material depth ≥ 750 mm

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Fig. 4: Typical Escape Ramps Design

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REFERENCES

1. A Policy on Geometric Design of Highways and Streets, 6th Edition, 2011. 2. C. D. Bartell, Design Guide for Truck Escape Ramps, 1986. 3. ITE Technical Committee 5B-1, Proposed Recommended Practice: Truck Escape Ramps. 4. Earl C. Williams and C. Franklin Horne, Runaway Truck Ramps Are Saving Lives and

Reducing, 1979. 5. Road Planning and Design Manual Chapter 15: Auxiliary Lanes, 2002. 6. Nevada Truck Escape Ramps, 2012. 7. Transmission Gulley Project, Assessment of Environmental Effect, Technical Report

No.1 (Road Design Philosophy), July 2011 8. Department of Transportation, Division of Traffic Engineering, Traffic Bulletin No. 24,

Design of Truck Escape Ramps, October 1986 9. AASHTO - A Policy on Geometric Design of Highways and Streets, 2004, 5th Edition. 10. Runaway Truck Escape Ramps Are Saving Lives and Reduce Damage, ITE Journal, May

1979, Earl C. Williams and C.Franklin Home 11. Geometric Design Guide - The Council for Scientific and Industrial Research (CSRI),

South Africa. 12. Design Guide for Truck Escape Ramps, 1986 - Edward J. Tye, Department of

transportation, State of California. 13. ROAD TALK - Ontario's Transportation Technology Transfer Digest - Fall 2009 - Vol.

15, Issue 4 14. Guide to Geometric Design of Rural Roads, AUSTROADS Part 8. 15. Truck Escape Ramp (TER) – Richard C. Hanley, P.E., Connecticut Department Of

Transportation.

Prepared by: Bahagian Kejuruteraan Forensik Pakar Kejuruteraan Jalan & Jambatan Cawangan Jalan JKR Malaysia.