**3. Children carriages' kinematics during driving vehicle maneuvers**

During the development of the ASUCAR project, a series of experimental tests were carried out whose objective was to reproduce the dynamic behavior of a ChC inside a public transport vehicle, under typical traffic maneuvers, such as sudden accelerations, critical braking, and extreme turns at maximum speed. The tests tried to reproduce urban and suburban traffic conditions and were implemented both in

closed and open circuits [14]. The closed-track tests were carried out at the facilities of the Institute for Automobile Safety Research (INSIA), from the Polytechnic University of Madrid, and at the facilities of the municipal transport operators of Valencia and Madrid. The open circuit tests took place in the streets of the cities of Valencia and Madrid (Spain). These open circuit tests were carried out with congested traffic, representing routes where frequent stops, traffic lights, roundabouts, tunnels, and slopes could be found on the bus tracks.

Transport vehicles of category M3 were selected. The vehicle model was a SCANIA N230 E4 with a CARSA City body. The maximum authorized weight was 19,000 kg, with a length of 11.99, 2.5 wide and 2.845 m high. During the trials three representative ChCs were used among the most up-to-date market models, based on their accessibility and safety features; thus, the most bulky, the heaviest, and the most unstable carriage models were defined as Model A, B, and C, respectively. **Table 1** shows the technical characteristics of the ChC used in the experimental trials. The ChCs were oriented during the tests in a direction parallel to the longitudinal axis of the vehicle, both in forward- and rearward-facing directions, and also perpendicular to the longitudinal axis of the vehicle. **Figure 6** shows a couple of examples of the configurations used in the field trials [9, 14].

In the trials three types of dummies were used to reproduce different ages of children: a newborn model to rehearse the ChC with horizontal carrycot, a 9-month mannequin to rehearse strollers and car seats, and a dummy of 3 years to test strollers. The newborn and 9-month mannequins represented, inertially, an equivalent mass of 3.4 and 9 kg, respectively. These two dummies did not use any type of instrumentation to measure accelerations as established by UNECE Regulation R44 [16]. In contrast, the 3-year-old dummy consisted of a TNO P3 model dummy, weighing 15 kg, which contained triaxial accelerometers on the head and chest, as required by the R44. The instrumentation used for data acquisition during the tests consisted of different sensors and signal conditioning systems. Specifically, a triaxial AHRS400CC gyroscope with a range of *2 g* was used, located in the center of gravity of the bus. With the gyroscope, the angles, angular velocities, and accelerations of the three axes could be measured. In each of the centers of gravity of the ChC, a Kistler K-Beam 8390A10 triaxial accelerometer with a range of *10g* was installed. For the data acquisition, an HBM MGCplus AB22 system connected to a portable PC for the configuration, control, and storage of the recorded information was used. All data was acquired at a frequency of 12 Hz, and several 12 V batteries were used to ensure system power.

All trials were recorded by several digital video cameras, anchored to the structure of the vehicle, for further analysis of the images. In some of them, several tests were reproduced simultaneously with different ChC and configurations, to save costs and time. The developed test battery tried to reproduce different behaviors of the ChC when traveling inside the vehicle. In that sense, three possible situations were identified for each of the ChC tested:


The first closed-track test consisted of a slalom test, consisting of passing the bus between five cones separated with a distance of 15 m from each other. The speed of the bus was around 25 km/h. The second closed-track test was to make the vehicle follow a circular path, similar to the passage through a roundabout. The turning

*Passive Safety of Children Carriages on Busses DOI: http://dx.doi.org/10.5772/intechopen.90613*


**Table 1.** *Technical characteristics of ChC used in dynamic tests (source: [14]).*

*Passive Safety of Children Carriages on Busses DOI: http://dx.doi.org/10.5772/intechopen.90613*

**Figure 6.**

*Provision of ChC deployed during experimental open circuit trials: (A) unfolded rearwards facing Model A carriage and forwards facing Model C carriage; (B) unfolded rearwards facing Model B carriage and forwards facing Model C carriage (source: [14])*

radius drawn by the vehicle ranged between 15 and 20 m, and the circulation speed reached between 20 and 25 km/h. This test was consistent with other similar trials such as those developed according to SAE J266 [17] or SAE J2181 [18] standards, both aimed at measuring the dynamic stability of trucks and busses. The third closed-track tests consisted of a braking test, representative of an emergency braking. The vehicle had to be driven in a straight line until reaching a speed of 50 km/h and then proceed to braking in the shortest possible time and the shortest distance, without the driver losing control of the vehicle.

The combination of the different configurations tested, both in open and closed tracks, allowed us to obtain a battery of 61 tests (17 combinations for each of the slalom, circular, and braking path tests and 10 combinations for open circuit tests), using different models of ChC, with different testing dummies, carriage orientations, and brake application status. For all tests, a sign criterion was used for the signals obtained, both for the vehicle and for the ChC, based on the reference system of ISO 4130 [19]. **Figure 7** shows three examples of the behavior of ChC during experimental testing in closed circuit. As can be seen, the dynamics of the vehicle movement during the tests performance can cause carriage, when it is not held by any restraint system, and the wheels are braked, to tip over, and its occupant could hit the ground and the interior parts of the transport vehicle. The overturn, in addition, could occur also when the ChC moves in a rearward-facing orientation, which is the transport configuration recommended by current legislation, UNECE Regulation R107 [11], for this type of products.

From the analysis of the results obtained, and the video recordings made, some conclusions could be drawn about the dynamic behavior of the ChC when subjected to typical maneuvers of urban transport vehicles. From each of the trials, it was concluded that:

#### A. Slalom test:

