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,進行這兩種速度測定的場地要求又都是按照《汽車道路試驗方法通則》（GB/T 12534）的規定，即“試驗道路 除另有規定外，各項性能試驗應在清潔、干燥、平坦的，用瀝青或混凝土鋪設的直線道路上進行。道路長2～3km，寬不小于8m，縱向坡度在此期間0.1% 以內”。由此可知，運輸車的高（低）車速數據測試都是特別指定在平直道路上進行的。

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.

運輸車屬于城區運輸類型車輛，其大部分運輸時間內要進行轉向，避讓行人及車輛等行駛動作，不大有可能做高車速行駛。更為重要的是，運輸車是由底盤車改裝而成的，其整車重心較改裝前的底盤車重心有了顯著增高；同時在其運輸途中攪拌筒帶動著混凝土翻轉，使其重心朝著攪拌筒轉動方向偏移，從而使其重心偏離攪拌筒軸線的垂直平面，以至于影響到整車行駛穩定性，易于在轉彎時發生側翻，尤其是在高速行駛時，將會導致較高的翻車事故發生率。

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.

急剎急轉，也常常是造成運輸車翻車的主要原因?；谝陨系恼J識，運輸車本身重心高，行車路況復雜，作為城區運輸車這一客觀存在，在其使用時應引起高度重視的是行駛穩定性，防止側翻。

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.

生產廠家不應在突出宣傳其高車速時，不對可能因之引發的翻車事故隱患予以切實的警告。更不能在使用說明書內將底盤高車速標注為整車高車速，不說明實際行駛時應遵從《技術條件》的規定：“攪動行駛時，高車速不得高于50km/h”。因此，在使用說明書中應充分明示高速行駛將有帶來翻車事故的高度危險性。

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.