Safety design and evaluation method of long-steep downgrade sections for expressway
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摘要: 统计了长大下坡路段交通事故的时空分布与车型分布, 分析了试验路段道路条件与交通事故成因。采用断面观测法测定长大下坡路段小客车运行速度, 建立了小客车运行速度预测模型。采用DHS-130XL红外观测仪测量车辆制动毂温度, 建立了货车制动毂温度预测模型。对长大下坡定义进行了界定, 确定了长大下坡路段合理平均纵坡指标值及对应坡长值, 提出了长大下坡安全设计与评价程序。分析结果表明: 在长大下坡路段, 小客车与货车交通事故的主要原因分别是超速及刹车失灵; 对小客车可采用运行速度作为安全评价指标, 而对货车可采用坡长与制动毂温度; 建议安全坡长、一般安全坡长、极限最大坡长对应的制动毂温度分别为200℃、220℃、260℃; 采取安全改善措施后, 试验路段交通事故减少42.3%, 伤亡事故减少76.2%, 改善措施有效。Abstract: The spatial and temporal distribution of traffic accidents and the distribution of vehicle types were counted for long-steep downgrade sections of expressway.The conditions of tested road sections and the causes of traffic accidents were analyzed.The running speeds of cars on expressway were surveyed by section observation method, and their running speed prediction model was formulated.The temperatures of brake drums for trucks were measured by DHS-130XL infrared observing instrument, and their temperature predict model was set up.The definition of long-steep downgrade was proposed.The indices of average longitudinal slope were determined, and the reasonable average longitudinal slope lengths of long-steep downgrade sections were determined.The safety design and evaluation method of long-steep downgrade were put forward.Analysis result shows that for long-steep downgrade sections, the main reasons of traffic accidents are overspeed and brake failure, the running speed can be used as the safety evaluation index for cars, while slope length and the temperature of brake drum for trucks.The temperatures of brake drum for security slope length, general safety slope length and maximum limit slope length are 200 ℃, 220 ℃ and 260 ℃ respectively.The amount of traffic accidents reduces by 42.3% and casualties reduces by 76.2% after setting some safe improvement measures at the sections, so the measures are effective.
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表 1 车辆速度数据
Table 1. Speeds of vehicles
桩号 断面85%位车速/ (km·h-1) 平均纵坡/% 坡长/km K82+690 91.55 4.90 0.00 K82+210 98.55 4.90 0.49 K81+520 97.00 4.74 1.17 K81+320 97.85 4.63 1.37 K80+400 98.85 4.59 2.29 K79+960 100.40 4.38 2.73 K79+520 101.36 4.45 3.17 K79+280 99.00 4.41 3.41 K79+040 102.95 4.38 3.65 K78+550 105.00 4.44 4.14 K78+060 105.50 4.49 4.63 K77+790 106.00 4.43 4.90 K77+520 107.75 4.39 5.17 K77+030 105.70 4.43 5.66 K76+540 107.00 4.47 6.15 K75+950 108.25 4.41 6.74 K75+360 108.16 4.36 7.33 K75+100 105.75 4.38 7.59 K74+840 109.00 4.39 7.85 K74+480 111.45 4.36 8.21 表 2 制动毂温度
Table 2. Temperatures of brake drums
坡长/km 平均纵坡/% 速度/ (km·h-1) 货车总质量/t 前轮制动毂温度/℃ 后轮制动毂温度/℃ 3.17 4.451 41 32 137 190 3.17 4.451 13 63 53 371 3.17 4.451 34 15 56 120 3.17 4.451 43 49 83 198 3.17 4.451 38 60 147 346 3.17 4.451 26 39 90 170 3.17 4.451 18 32 166 135 3.17 4.451 27 18 75 160 3.17 4.451 38 29 70 205 3.17 4.451 57 19 90 184 7.33 4.360 48 38 90 362 7.33 4.360 37 47 77 259 7.33 4.360 30 38 82 256 7.33 4.360 24 25 63 222 7.33 4.360 30 30 128 315 7.33 4.360 20 30 216 161 7.33 4.360 20 26 114 77 7.33 4.360 19 7 83 155 7.33 4.360 24 13 50 191 7.33 4.360 32 17 132 215 7.33 4.360 30 16 95 198 9.69 4.046 29 40 153 242 9.69 4.046 19 45 148 228 9.69 4.046 25 80 81 364 9.69 4.046 27 80 56 463 9.69 4.046 24 60 154 271 9.69 4.046 34 68 81 427 9.69 4.046 20 80 164 232 9.69 4.046 39 14 72 188 9.69 4.046 37 7 124 136 9.69 4.046 76 17 182 274 9.69 4.046 64 49 140 288 12.25 3.640 31 70 152 411 12.25 3.640 29 13 56 157 12.25 3.640 42 20 71 229 12.25 3.640 30 20 97 198 12.25 3.640 61 18 124 236 12.25 3.640 37 11 76 296 12.25 3.640 40 10 121 215 12.25 3.640 60 50 146 232 12.25 3.640 55 9 79 186 12.25 3.640 44 20 145 253 表 3 模型系数
Table 3. Model coefficients
参数 非标准化系数 标准化系数 t检验值 95%置信区间 系数 标准差 低限 高限 常数项 -310.064 410.654 -0.75 -1142.13 522.00 ln (L/m) 54.870 32.850 0.336 1.67 -11.69 121.43 ln (G/%) 46.990 222.331 0.044 0.21 -403.50 497.48 ln[VH/ (km·h-1) ] 26.647 26.453 0.125 1.00 -26.95 80.24 ln (M/t) 85.587 13.930 0.712 6.14 57.36 113.81 表 4 极限最大坡长
Table 4. Maximum limit slope lengths
km 货车总质量/t 纵坡/% 车速/ (km·h-1) 40 50 60 40 3.5 5.88 5.27 4.83 4.0 5.24 4.70 4.31 4.5 4.74 4.25 3.89 5.0 4.33 3.89 3.56 60 3.5 3.12 2.80 2.56 4.0 2.79 2.50 2.29 4.5 2.52 2.26 2.07 5.0 2.30 2.06 1.89 表 5 高速公路安全坡长
Table 5. Safety slope lengths of expressway
km 平均纵坡/% 极限最大安全坡长 一般最大安全坡长 安全坡长 3.5 7.56 (8.0) 3.65 (4.0) 2.53 (3.0) 4.0 6.74 (7.0) 3.25 (3.0) 2.26 (2.0) 4.5 6.10 (6.0) 2.94 (3.0) 2.04 (2.0) 5.0 5.57 (6.0) 2.69 (3.0) 1.87 (2.0) 5.5 5.13 (5.0) 2.48 (3.0) 1.72 (2.0) 表 6 长大下坡路段事故数
Table 6. Accident numbers at long-steep downgrade sections
路段 措施前事故数 措施后事故数 K68+100~K68+720 9+64 4+39 K69+440~K69+740 3 1 K70+040~K70+440 7 3 K72+300~K73+060 5 2 K75+360~K76+540 12 7 K76+540~K77+520 15 8 K79+960~K80+860 14 10 注: 事故数中9+64是在路段上发生9起交通事故, 收费站处发生64起交通事故。 -
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