A vehicle control system comprising: an autonomous travel vehicle; a manned vehicle; and a plurality of communication lines (510, 520, 550) configured to connect the autonomous travel vehicle and the manned vehicle with each other, wherein the manned vehicle is configured to transmit positional information about the manned vehicle by using a first communication line, the autonomous travel vehicle is configured to use the first communication line to receive the positional information about the manned vehicle, the autonomous travel vehicle is configured to decide whether or not an inter-vehicle distance between the autonomous travel vehicle and the manned vehicle is equal to or shorter than a reference distance on a basis of the positional information about the manned vehicle and positional information about the autonomous travel vehicle, in a case where the inter-vehicle distance is equal to or shorter than the reference distance, the autonomous travel vehicle is configured to - decide whether or not a second communication line that uses a communication path different from the first communication line is established between the autonomous travel vehicle and the manned vehicle, - set an upper limit of a travel speed of the autonomous travel vehicle to a first speed in a case where it is decided that the second communication line is established, and travels under the upper limit, - set the upper limit of the travel speed of the autonomous travel vehicle to a second speed, which is not zero, in a case where it is decided that the second communication line is not established, and travels under the upper limit, wherein a communication delay related to the second communication line is shorter than a communication delay related to the first communication line, and wherein the first speed is higher than the second speed. an autonomous travel vehicle; a manned vehicle; and a plurality of communication lines (510, 520, 550) configured to connect the autonomous travel vehicle and the manned vehicle with each other, wherein the manned vehicle is configured to transmit positional information about the manned vehicle by using a first communication line, the autonomous travel vehicle is configured to use the first communication line to receive the positional information about the manned vehicle, the autonomous travel vehicle is configured to decide whether or not an inter-vehicle distance between the autonomous travel vehicle and the manned vehicle is equal to or shorter than a reference distance on a basis of the positional information about the manned vehicle and positional information about the autonomous travel vehicle, in a case where the inter-vehicle distance is equal to or shorter than the reference distance, the autonomous travel vehicle is configured to - decide whether or not a second communication line that uses a communication path different from the first communication line is established between the autonomous travel vehicle and the manned vehicle, - set an upper limit of a travel speed of the autonomous travel vehicle to a first speed in a case where it is decided that the second communication line is established, and travels under the upper limit, - set the upper limit of the travel speed of the autonomous travel vehicle to a second speed, which is not zero, in a case where it is decided that the second communication line is not established, and travels under the upper limit, wherein - decide whether or not a second communication line that uses a communication path different from the first communication line is established between the autonomous travel vehicle and the manned vehicle, - set an upper limit of a travel speed of the autonomous travel vehicle to a first speed in a case where it is decided that the second communication line is established, and travels under the upper limit, - set the upper limit of the travel speed of the autonomous travel vehicle to a second speed, which is not zero, in a case where it is decided that the second communication line is not established, and travels under the upper limit, wherein a communication delay related to the second communication line is shorter than a communication delay related to the first communication line, and wherein the first speed is higher than the second speed.