High vehicle speed is one of the three major indexes of vehicle power. Transport vehicle manufacturers attach great importance to this index and list it as an important performance index. In fact, all vehicle speed tests are conditional. The technical conditions stipulates that the high speed test of transport vehicles is in accordance with the high speed test method of motor vehicles (GB / T 12544); the low speed test is in accordance with the low stable speed test method of motor vehicles (GB / T 12547).

然而,进行这两种速度测定的场地要求又都是按照《汽车道路试验方法通则》（GB/T 12534）的规定，即“试验道路 除另有规定外，各项性能试验应在清洁、干燥、平坦的，用沥青或混凝土铺设的直线道路上进行。道路长2～3km，宽不小于8m，纵向坡度在此期间0.1% 以内”。由此可知，运输车的高（低）车速数据测试都是特别指定在平直道路上进行的。

However, The site requirements for these two speed measurements are in accordance with the provisions of general rules for automobile road test methods (GB / T 12534), that is, "unless otherwise specified, all performance tests of the test road shall be carried out on a clean, dry and flat straight road paved with asphalt or concrete. The road is 2 ~ 3km long, no less than 8m wide, and the longitudinal slope is within 0.1% during this period" 。 It can be seen that the high (low) speed data tests of transport vehicles are specially designated to be carried out on straight roads.

运输车属于城区运输类型车辆，其大部分运输时间内要进行转向，避让行人及车辆等行驶动作，不大有可能做高车速行驶。更为重要的是，运输车是由底盘车改装而成的，其整车较改装前的底盘车有了显著增高；同时在其运输途中搅拌筒带动着混凝土翻转，使其朝着搅拌筒转动方向偏移，从而使其偏离搅拌筒轴线的垂直平面，以于影响到整车行驶稳定性，易于在转弯时发生侧翻，尤其是在高速行驶时，将会导致较高的翻车事故发生率。

Transport vehicles are urban transport vehicles. They have to turn and avoid pedestrians and vehicles during most of the transportation time. It is unlikely to drive at high speed. More importantly, the transport vehicle is refitted from the chassis vehicle, and the center of gravity of the whole vehicle is significantly higher than that of the chassis vehicle before refitting; At the same time, during transportation, the mixing drum drives the concrete to overturn, making its center of gravity offset towards the rotation direction of the mixing drum, so that its center of gravity deviates from the vertical plane of the axis of the mixing drum, so as to affect the driving stability of the whole vehicle, and it is easy to roll over when turning, especially at high speed, which will lead to a high incidence of rollover accidents.

急刹急转，也常常是造成运输车翻车的主要原因。基于以上的认识，运输车本身高，行车路况复杂，作为城区运输车这一客观存在，在其使用时应引起高度重视的是行驶稳定性，防止侧翻。

Sudden braking and sudden turning are often the main reasons for the rollover of transport vehicles. Based on the above understanding, the transport vehicle itself has a high center of gravity and complex driving road conditions. As an objective existence of urban transport vehicle, great attention should be paid to driving stability and preventing rollover.

生产厂家不应在突出宣传其高车速时，不对可能因之引发的翻车事故隐患予以切实的警告。更不能在使用说明书内将底盘高车速标注为整车高车速，不说明实际行驶时应遵从《技术条件》的规定：“搅动行驶时，高车速不得高于50km/h”。因此，在使用说明书中应充分明示高速行驶将有带来翻车事故的高度危险性。

The manufacturer shall not give a practical warning to the potential rollover accident that may be caused when highlighting its high speed. Moreover, it is not allowed to mark the high speed of the chassis as the high speed of the whole vehicle in the operation manual, which does not indicate that the actual driving shall comply with the provisions of the technical conditions: "when stirring driving, the high speed shall not be higher than 50km / h". Therefore, it should be fully stated in the operation manual that high-speed driving will bring high risk of rollover accident.