Abstract: The following distance alarming apparatus includes a memory responsive to an output signal value of a sensor, which changes in accordance with a driver's operation for speed adjustment of a subject vehicle, having remained unchanged for a prescribed time period, for storing a reference value for the output signal value of the sensor, and an alarming circuit determining a possibility of collision of the subject vehicle with a preceding vehicle, based on a following distance measured by a following distance measuring device when the output signal value from the sensor remained unchanged for the prescribed time period, the output signal value from the sensor and the reference value stored in the memory, and outputting a warning sound.

Abstract: The following distance alarming apparatus includes a memory responsive to an output signal value of a sensor, which changes in accordance with a driver's operation for speed adjustment of a subject vehicle, having remained unchanged for a prescribed time period, for storing a reference value for the output signal value of the sensor, and an alarming circuit determining a possibility of collision of the subject vehicle with a preceding vehicle, based on a following distance measured by a following distance measuring device when the output signal value from the sensor remained unchanged for the prescribed time period, the output signal value from the sensor and the reference value stored in the memory, and outputting a warning sound.

Abstract: A following distance displaying apparatus which enables visual confirmation how much more approach between a preceding vehicle and a subject vehicle makes a distance at which an alarm of a following distance alarming apparatus operates, after a lapse of a predetermined time from when the preceding vehicle and the subject vehicle entered a follow-up travel state, indicates an alarm distance at which the alarm of the following distance alarming apparatus operates which is set in advance corresponding to the then following distance to the preceding vehicle and an approach distance representing a difference between the subsequently measured following distance and said alarm distance.

Abstract: An rear-end collision alarming device issuing an alarm for preventing a rear-end collision against a vehicle running ahead determines whether a gas pedal is operated when it is determined that a subject vehicle approaches the vehicle running ahead. If the gas pedal is not operated, this means that a driver does not react to the approach. Therefore, the device notify the driver of the approach to the vehicle running ahead through an alarm sound or light.