ASIAN HIGHWAY DESIGN STANDARD FOR ROAD SAFETY DESIGN GUIDELINES October 2017 This document consists of recommended guidelines related to the “Asian Highway Design Standard for Road Safety” to the Intergovernmental Agreement on the Asian Highway Network. While the guidelines are not mandatory in nature, the member countries of the Asian Highway network are encouraged to refer to the principles and recommendations given in the document for new road projects and improvements of existing sections of Asian Highway routes under their jurisdiction. Due to the diverse circumstances of the Asian Highway Network, the adoption of particular recommendations would need to take into account prevailing social, economic and technical considerations. In all cases, sound engineering skills are required to formulate specific solutions to address project issues which could be complex in reality. Flexibility and innovations are desirable as far as safety performance is not undermined and consistency is reasonably maintained. This document does not necessarily reflect the view of the United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP). ASIAN HIGHWAY DESIGN STANDARD FOR ROAD SAFETY DESIGN GUIDELINES October 2017 I Acknowledgements This document has been prepared by Julian T.H. Kwong, international road safety consultant under the direction and guidance of Mr. Ishtiaque Ahmed, Economic Affairs Officer, Transport Infrastructure Section, Transport Division as the project manager. Valuable advices were extended by Mr. Pierre Chartier, Section Chief, Transport Infrastructure Section and Mr. Yuwei Li, Director, Transport Division of the United Nations Economic and Social Commission for Asia and the Pacific (ESCAP). Mr. Jeongsu Park, Expert from the Republic of Korea to ESCAP also contributed to the study. The development of the Design Standards and Design Guidelines has been realised with the generous support of the Korean Expressway Corporation (KEC) under the direction of Dr Sung-Min Cho, Director of R&D Planning Office. In the early stage, technical studies were conducted by Dr. Ducknyung Kim of KEC and Mr Greg Smith of the International Road Assessment Programme (iRAP). Their findings laid down the foundation for the preparation of this document. The following countries participated in the project by providing up to date information on their current design standards and usage of road safety infrastructure facilities. National Experts from the above member countries have provided inputs as national reports: • Bangladesh (Mr. Noor-E-Alam) • China (Prof. Xiaojing Wang) • India (Mr. Tony Mathew) • Republic of Korea (Dr. Sung-min Cho) • Thailand (Mr. Sujin Mungnimit) Experts and delegates from member countries of the Asian Highway Network have offered valuable comments on the development of this document. The international consultant would also wish to express his appreciation to Mr C.K. Nip (Hong Kong) and Mr Peter Monger (United Kingdom) for their technical advice. II ASIAN HIGHWAY NETWORK DESIGN STANDARDS FOR ROAD SAFETY- DESIGN GUIDELINES Table of Contents Part 1 ROAD NETWORK 1 GENERAL CONSIDERATIONS ...................................................................................................... 2 1.1 Network Development ............................................................................................................ 2 1.2 Interfaces ................................................................................................................................ 6 1.3 Transition Zones ...................................................................................................................... 8 2 SPEED LIMITS ......................................................................................................................... 10 2.1 General Considerations ......................................................................................................... 10 2.2 Setting Speed Limits .............................................................................................................. 13 Part 2 ROAD INFRASTRUCTURE 1 OVERVIEW ............................................................................................................................. 18 2 ALIGNMENT AND CROSS-SECTIONS ........................................................................................ 19 2.1 Visibility ................................................................................................................................. 19 2.2 Design Speed and Alignment ................................................................................................ 24 2.3 Cross-sections ....................................................................................................................... 27 2.4 Overtaking ............................................................................................................................. 33 2.5 “2+1” Overtaking Sections and “2+1” Roads ........................................................................ 40 2.6 Changes in Cross-sections ..................................................................................................... 43 2.7 Sharp Curves ......................................................................................................................... 45 2.8 Steep Downhill Gradient ....................................................................................................... 50 2.9 Climbing Lanes ...................................................................................................................... 55 3 PARKING AREAS ..................................................................................................................... 58 3.1 General Requirements .......................................................................................................... 58 3.2 Parking Laybys ....................................................................................................................... 58 3.3 Rest Areas ............................................................................................................................. 62 3.4 Service Areas ......................................................................................................................... 63 3.5 Bus Facilities .......................................................................................................................... 65 3.6 Roadside Stalls ...................................................................................................................... 69 4 SPECIAL FACILITIES ................................................................................................................. 70 4.1 Toll Plazas .............................................................................................................................. 70 4.2 Border Control Points ............................................................................................................ 71 i ASIAN HIGHWAY NETWORK DESIGN STANDARDS FOR ROAD SAFETY- DESIGN GUIDELINES 4.3 Emergency and Maintenance Facilities................................................................................. 72 4.4 Facilities for Wildlife and Animals ......................................................................................... 75 5 ROAD PAVEMENT ................................................................................................................... 77 5.1 Skid Resistance ...................................................................................................................... 77 5.2 Road Drainage ....................................................................................................................... 80 5.3 Pavement Defects ................................................................................................................. 83 PART 3 INTERSECTIONS 1 OVERVIEW ............................................................................................................................. 88 1.1 General Requirements .......................................................................................................... 88 1.2 At-grade Intersections ........................................................................................................... 90 1.3 Channelisation ...................................................................................................................... 92 2 PRIORITY INTERSECTIONS ....................................................................................................... 93 2.1 General Requirements .......................................................................................................... 93 2.2 Simple Intersections .............................................................................................................. 98 2.3 Side Road Channelising Islands ........................................................................................... 100 2.4 Protected Offside Turn Lane with Painted Traffic Islands ................................................... 102 2.5 Protected Offside Turn Lane with Physical Traffic Islands ................................................... 104 2.6 Direct Frontage Accesses .................................................................................................... 108 3 ROUNDABOUTS ................................................................................................................... 112 3.1 General Requirements .......................................................................................................