Guideline for Highway Safety Audit

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• Publié par: Udwe
• Nombre de lectures: 60
• Langue: English

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  Guideline for Highway Safety Audit PRC (JTG/T B05-2004)  

Issued on 1 September 2004   Effective on 1 November 2004

Prepared by: Chelbi Engineering Consultants Inc., PRC     Approved by: Ministry of Communications, PRC     Translated under : TA4322-PRC: Poverty Impact of Area Wide Road Networks

FOREWORDS  In order to comply with national social and economic development requirements, the Ministry of Communications of PRC (MOC), pursuant to No. 82 Document (1999), determined to undertake preparation of“Guideline for Highway Safety Audit”  (hereinafter called as“the Guideline”), which was responsible by Chelbi Engineering Consultants Inc. and participated jointly by Tongji University and Shandong Transport Scientific Institute. During the preparation, large supports and coordination were given by Highway Scientific Institute of MOC, Chongqing Municipal Transport Committee, Liaoning Expressway Management Bureau, Beijing University of Technology and Guangdong Expressway Co., Ltd, etc.  Based on the analyses and tracks on outcomes of Road Safety Audit in Europe and American countries, the preparation and study team of theGuideline, according to the special situation of China, selected several representative highways for survey and study, such as Shenyang to Dalian Expressway in Liaoning Province, Jinan to Qingdao and Yantai to Qingdao Expressways in Shandong Province, Taiyuan to Gejiu Expressway in Shanxi Province, Chengdu to Chongqing Expressway in Chongqing, Hankou to Yichang Expressway in Hubei Province, Shanghai to Nanjing Expressway in Jiangsu Province and Tulufan to Urumchi to Dahuangshan High Class Highway, etc. Based on large amounts of statistical analyses, the relationships between traffic accidents and highway geometrical indicators, traffic accidents and operating speed, as well as highway geometrical indicators and operating speed were deeply studied and relevant road safety audit contents, methods and standards for expressway and first class highway were provided preliminarily, which would play positive role in implementation of safety audit and further guarantee and improvement of road safety in China.  Due to the short period of implementation of road safety audit and limited study time, there would be inevitable shortages in the Guideline. Any units and individuals who use this Guideline could inform Chelbi Engineering Consultants Inc. once finding any issues or having any comments to following address: No. Ding 28, Guozijian Street, Annei, Dongcheng District, Beijing; Postal Code: 100007; Telephone: [phone]; Fax: [phone].   Prepared by:   Engineering Consultants Inc. Chelbi  Jointly with : Tongji University  Shandong Transport Scientific Institute  Compilers: Zhou Haitao Yang Chunhui Guo Zhongyin  Fang Shoun Wang Guangshan Xin Chao  Cui Junsheng

Guideline for Highway Safety Audit (JTB/T B05-2004)

1 GENERAL

    1.0.1 OBJECTIVE    To reduce traffic accidents and decline the hazardous extent of traffic accidents, the Guideline would carry out road safety audit for feasibility study, design outcome and operation of highway project from the viewpoint of safety of road user.  1.0.2 APPLICATION    The Guideline is applicable to road safety audit of expressway and new construction and/or reconstruction of first class highway. For other highways of other classes, it could be used as reference.  1.0.3 REPRESENTATIVE VEHICLE TYPE     The representative vehicle type shall be selected according to the most disadvantageous principle for highway safety audit.  1.0.4 STUDY PHASES     Highway safety audit could be divided into three phases, feasibility study phase, design phase and operation phase.  1.0.5 REQUIREMENT TO OUTCOME    “Highway Safety Audit Report”shall be prepared after completion of highway safety audit to feasibility study, design outcome and operation of highway project using this Guideline, which forms and contents are shown in Appendix A.  1.0.6 FOUNDATION    The Guideline is prepared based on“Highway Law of PRC”,“Highway Engineering Technical Standards” by MOC and other relevant criteria and issued specifications. Contents in this Guideline would be changed automatically upon the changes of relevant national regulations, standards and specifications.

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Guideline for Highway Safety Audit (JTB/T B05-2004)

2 GLOSSARY

  2.0.1 HIGHWAY SAFETY AUDIT   Highway Safety Audit is a systemic evaluation process for highway operation safety, which introduces concepts of highway operation safety and reduction of traffic accidentintothefeasibilitystudyanddesignofhighwayproject.Itisabasicprocedurein highway construction and management.  2.0.2 CONSISTENCY OF OPERATING SPEED   The Operating Speed refers to the driving speed measured at the 85 th percentile on feature point when the traffic is in free flow situation with better weather. The Consistency of Operating Speed is an indicator to evaluate the consistency of alignment design, using the varied value of operating speed between adjacent road sections for evaluation.  2.0.3  ROADSIDE   Roadside refers to the area between outer edge of pavement (hard shoulder) and right of way.   2.0.4  CLEAR ZONE OF ROADSIDE   The clear zone is adjacent to the carriageway, within which no objects which have potential hazard to any lose control vehicles would exist under the circumstance of no protection measures. The clear zone consists of hard shoulder, earth shoulder and gentle slope which could control the vehicle, which width is determined by forecast traffic, operating speed and road geometrical indicators, etc.  2.0.5  EMERGENCY ESCAPING LANE   Referring to the lane arranged at roadside at middle and end parts of long steep down slope for lose control vehicles (such as brake failure), particularly for heavy truck, to drive off the main lane, to decelerate and to stop.

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Guideline for Highway Safety Audit (JTB/T B05-2004)

3 ENGINEERING FEASIBILITY STUDY PHASE   3.1 TECHNICAL STANDARD  3.1.1 HIGHWAY CLASSIFICATION     According to distribution of cities and townships and populations along the roadside, forecast traffic, traffic component, the project function and its role in the network, it shall carry out evaluation to the proposed highway classification from the concern of adaptability to operating safety.   3.1.2 DESIGN SPEED     The safety audit shall be carried out to design speed based on proposed highway classification, forecast traffic, traffic component and terrain along roadside. The design speed differences between two adjacent road sections with different design speed shall not exceed 20km/h. For adjacent road sections which speed difference is more than 20km/h, the transition section shall be arranged, which length shall guarantee the transition requirements of alignment indicators. Also, relevant traffic facilities shall be arranged to instruct driver to adjust operating speed.  3.1.3 WIDTH OF CROSS SECTION OF SUBGRADE    1For new construction project, it shall evaluate the adaptability of cross section type of subgrade and width of carriageway, hard shoulder, median divider and margin from the viewpoint of safety audit based on forecast traffic and traffic component; 2For project being implemented by stages, the impact of front-end works and after reserved works to the operation safety shall be evaluated according to long term planning; and 3For reconstruction and extension project, the impact of consistency of changes of subgrade width and facilities to the operation safety shall be evaluated.   3.2 TECHNICAL PROPOSAL    3.2.1 TECHNICAL INDICATOR     The horizontal and longitudinal alignment indicators shall comply with the design speed requirement. The vertical section, cross section and plane indicators shall be improved for projects which are mainly used by large and medium trucks. The impacts of near future works to the operating safety shall be noticed for projects being implemented by stages. For reconstruction and extension projects, more attentions shall be paid to the consistency of changes of technical indicators before and after reconstruction and their impacts to the safety.  3.2.2 ORIGIN AND DESTINATION     According to the forecast traffic, the link mode and traffic component of origin and destination of the route with linking roads shall be evaluated.  3.2.3 INTERSECTION     Based on the terrain, technical indicators of mainline, situation of intersected route and forecast traffic, the necessity, type, traffic organization and distance of - 3 -  

Guideline for Highway Safety Audit (JTB/T B05-2004)

intersections shall be evaluated. The evaluation standard shall be as reducing the conflict points to minimum.  3.2.4 INTERCHANGE     According to network condition, traffic condition and location of townships and villages, the necessity, type, linking mode with intersected roads and spaces between adjacent interchanges, such large structures as tunnels and other management facilities shall be evaluated. If the minimum space shall not meet with current specifications, such safety facilities as auxiliary lane, marks and signs shall be added.  3.2.5 FLYOVER AND PASSAGE     For other intersections at where no grade crossing or interchanges are arranged, the necessity and arrangement space of flyover or passage shall be evaluated.  3.2.6 TRAFFIC ORGANIZATION DURING CONSTRUCTION PERIOD   If the reconstruction project shall not interrupt traffic or divert the traffic of mainline to other roads during construction period, the safety impact of construction organization proposal and relevant safety measures shall be evaluated.   3.3   ENVIRONMENTAL IMPACT    3.3.1 CLIMATE     According to national climate condition such as rain, frost, snow, fog and crosswind, etc. safety measures adopted under circumstance of various natural climate conditions in engineering proposal shall be evaluated.  3.3.2 UNFAVORABLE GEOLOGY CONDITION     Safety measures used for unfavorable geological condition in engineering proposal shall be evaluated based on actual geological situation.   3.3.3 ANIMALS     The necessity of arrangement of isolation bar or animal special passage shall be evaluated according to situation of animals movement area and their migration route.

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Guideline for Highway Safety Audit (JTB/T B05-2004)

4 DESIGN PHASE   4.1 OVERALL EVALUATION   4.1.1 DESIGN CONFORMANCE     The design conformance review shall focus on the accuracy of technical indicators adopted in project design and find out any technical indicators which are conform to current standards and specifications according to relevant requirements stipulated in current regulations and approved technical standard for the project by relevant authorities.  4.1.2 CONSISTENCY OF OPERATING SPEED     The consistency of operating speed evaluation is to evaluate the operating speed difference between adjacent road sections. The adjacent road sections refer to connected road sections with different horizontal, longitudinal and cross section indicators or with different design speed, commonly referring to the front and behind road sections located by the origin of horizontal curve, middle point of curve, grade change point or points at where the width of cross section is changed.  1 Evaluation Method     Using operating speed estimation method to forecast the operating speed at each alignment characteristic point (origin and middle points of straight line, origin and destination of horizontal curve, middle point of curve and grade change point on vertical curve, etc) in adjacent road sections and calculate the speed difference. The specific calculation method is shown in Appendix B.   2 Evaluation Standard   The evaluation indicator shall use∆V 85 , the operating speed difference of adjacent road sections. |∆V 85  consistency|< 10 km/h: of operating speed is fine;  |∆V 85 | is 10-20km/h: consistency of operating speed is fair. The technical indicators in   adjacent road sections shall be adjusted when condition is   permitted, making the speed difference≤10 km/h;  |∆V 85 |> 20km/h: consistency of operating speed is poor. The horizontal and cross section design of adjacent section shall be adjusted.   4.1.3 CONSISTENCY OF DESIGN SPEED AND OPERATING SPEED     The evaluation of consistency of design speed and operating speed is to evaluate the speed difference between the design speed and operating speed for the same road section. The same road section refers to that section with same design speed, technical indicator of horizontal and vertical profile and cross section.   The design speed for the same road section shall adopt the approved technical standard of the project. The operating speed of same road section shall be calculated according to regulation set forth in Item 4.1.2. If the speed difference between design speed and operating speed for the same road section is more than 20km/h, the safety checking computation shall be undertaken to relevant technical indicators based on the Guideline.

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Guideline for Highway Safety Audit (JTB/T B05-2004)

  4.2 ROUTE    4.2.1 EVALUATION SCOPE     The evaluation shall be carried out for common road section at where the speed defference between design speed and operating speed is more than 20km/h.   4.2.2 PLANE   1 Radius of Horizontal Curve    1) Evaluation Method   Under the premise of unchanged transverse grade of crown, the radius of horizontal curve shall be calculated with the calculated value of operating speed of the road section. If the radius value calculated with operating speed is larger than that corresponding to the design speed, a technical and economic comparison shall be conducted between increasing radius of horizontal curve corresponding to design speed and decreasing radius of horizontal curve corresponding to operating speed.  FollowingFormula 4.2.2shall be used for calculation of radius of horizontal curve.   R 127 V ∗( 85 µ 2 +i) =  (4.2.2)  Where, R - Radius of horizontal curve (m) required by operating speed; V 85   of operating speed (km/h); Value -  - Coefficient of lateral force; and i - Transverse grade of crown (%)   2) Evaluation Standard     If the transverse grade corresponding to the design speed is not changed, the increased radius of horizontal curve shall not be less than the radius of horizontal curve corresponding to the operating speed and length of round curve shall not be less than the distance driving 3s with operating speed. If the radius of horizontal curve corresponding to the design speed is not changed, the transverse grade of superelevation shall be adjusted according to Item 4.2.7. If the radius of horizontal curve and transverse grade corresponding to the design speed are limited, relevant modification and control measures shall be adopted to reduce speed difference between design speed and operating speed.  2 Transition Curve     The parameters of transition curve shall be modified corresponding to changes of operating speed V 85 radius of round curve and transverse grade of superelevation.to When modifying, the equilibrium of parameter value for adjacent transition curves shall be considered. When evaluating the transition curve, its length shall meet with minimum length requirement of transition zone of superelevation. Also, the increase of transition curve resulted by change of variation ratio of transverse acceleration shall be considered. 

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Guideline for Highway Safety Audit (JTB/T B05-2004)

3 Length of Shortest Straight      The evaluation of length of shortest straight shall use the operating speed value, V 85 .      If the difference between V 85 and design speed is≤20km/h, the length of straight shall not be changed.   If the difference between operating speed and design speed is more than 20km/h, the shortest length of straight (m) between reverse round curves shall not be less than two times of operating speed V 85 (km/h) and that between adjacent curves shall not be  less than six times of operating speed V 85 (km/h).   4.2.3 STOPPING SIGHT DISTANCE    1 Evaluation Method    1) Stopping Sight Distance for Car     The stopping sight distance for car shall be calculated with operating speed. If the distance calculated with operating speed is larger than that with design speed, the stopping sight distance shall be increased. The stopping sight distance shall be calculated with followingFormula 4.2.3-1 .    S V 85 *t + ( V 85 / g 3.6 f ) 2 c = 3.6 2∗ ∗  (4.2.3-1)  Where, S c  sight distance for car (m);- Stopping V 85  value of operating speed (km/h);- Calculated t - Waste time, i.e. reaction time, shall be 2.5s (1.5s of judgment time and  1.0s of operating time); g Acceleration of gravity=9.8m/s 2 ; and -  - Coefficient of longitudinal friction, determined by operating speed and   pavement condition.   According toFormula 4.2.3-1and estimated operating speed, the stopping sight distances for car are summarized in following Table 4.2.3-1.  Table 4.2.3-1 Calculation of Stopping Sight Distance for Car  Operating Reaction Coefficien Braking and Sight Speed (km/h)  Time t of Stopping Distance (s) Friction Distance (m) (m) 120 2.5 0.29 279 280 110 2.5 0.29 241 245 100 2.5 0.3 201 205 90 2.5 0.3 169 170 80 2.5 0.31 137 140 70 2.5 0.32 109 110 60 2.5 0.33 85 90

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Guideline for Highway Safety Audit (JTB/T B05-2004)

2) Stopping Sight Distance for Truck     The stopping sight distance for truck shall be evaluated with calculated value of operating speed at potential blackspots for trucks or large passenger vehicles, such as compound curve, deceleration lane, end part of out ramp, intersection in hilly area, intersection near pier and grade cross located at or near protruding vertical curve, etc.  FollowingFormula 4.2.3-2shall be used for stopping sight distance for trucks.  S V 3 8 . 5 6 *t + 2 ( V g 85 / ( 3 f .6 ) 2 i)  (4.2.3-2)  = c  +∗ ∗ Where, S t  sight distance for trucks (m);- Stopping V 85  value of operating speed of trucks (km/h);- Calculated t - Reaction time (s), valued according to different operating time, shown in Table 4.2.3-2；  g - Acceleration of gravity=9.8m/s 2 ; i - Vertical grade of alignment (up slope with 2% grade is i=0.02 and down  slope with 4.5% grade is i=-0.045). Modification value of vertical slopes  are shown in Table 4.2.3-3; and  - Coefficient of longitudinal friction between tyre of truck with pavement  valued as 0.17 not considered the operating speed.  Table 4.2.3-2 Calculation of Stopping Sight Distance for Trucks on Flat Slope  Operating Speed Reaction Ti  topping Sight (km/h) (s)  me C of o   e F f r f i i c c t i i e o n n t     S D T i r s u ta c n ks c   e (   m fo )  r  110 2.5 0.17 356 100 2.5 0.17 301 90 2.5 0.17 251 80 2.4 0.17 202 70 2.3 0.17 158 60 2.2 0.17 120  Table 4.2.3-3 Modification Value of Stopping Sight Distance for Trucks on Up and Down Slopes  Unit: m Operating Up Slope Down Slope Speed (km/h)  -2%+2% +4% +6% -4% -6% 110 -29 -53 -73 56 86 153 100 -24 -44 -60 46 71 126 90 -20 -36 -49 38 58 102 80 -16 -28 -39 30 46 81 70 -12 -22 -30 23 35 62 60 -9 -16 -22 17 26 45  Note: 1. Design values in Table are calculated based on wet pavement; and 2. The stopping sight distance shall increase 10% after modification of slope grade for horizontal curve section which radius is less than 400m.

     

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Guideline for Highway Safety Audit (JTB/T B05-2004)

2) Evaluation Standard     The sight distance corresponding to the design speed shall not be less than the stopping sight distance for cars calculated with operating speed. In the potential blackspot area for trucks or large passenger vehicles, the design sight distance shall be large than stopping sight distance for trucks calculated with the operating speed of trucks.  4.2.4 PROFILE    1 Evaluation Method   The grade and length of slope section and radius of vertical curve shall be evaluated using the calculated value of operating speed.  2 Evaluation Standard     If the difference between operating speed and design speed is≤20km/h, the grade and length of grade and radius of vertical curve shall not change;   If the difference between operating speed and design speed is >20km/h, the grade and length of grade and radius of vertical curve shall be modified according to the calculated value of operating speed.   4.2.5 CROSS SECTION  1 Width of Subgrade Cross Section     The evaluation of width of subgrade cross section shall be carried out with the calculated value of operating speed.   If the difference between operating speed and design speed is≤20km/h, the width of subgrade cross section of corresponding road section shall not change;   If the difference between operating speed and design speed is >20km/h, the width of subgrade cross section shall be modified according to calculated value of operating speed. The modified road section length shall meet with requirements in “Highway Engineering Technical Standards”. The transition zone shall be arranged at where the width of subgrade cross section has changed, which shall be considered together with transition zones in interchange or other intersections and shall avoid changes in common road sections. If the arrangement of transition zone in common road sections are unavoidable, the length of transition zone shall be in accordance with relevant requirements for length of transition zone in speed change lanes regulated in “Highway Alignment Design Specifications”.   2 Climbing Lane     If the difference between calculated value of operating speed for trucks at the top of climbing section and design speed is lower than 20km/h, or it could not meet with the design service level, the necessity of arrangement of climbing lane shall be evaluated.   For road sections which have arranged climbing lanes, the length, width, signs and marks of climbing lane shall be evaluated.    

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