Jord: Dawn of a World
Created by the Mavolians with aid from The Givers, these apparatus are dual-ballistas set side-by-side, with a rolled plank bridge between them. The ballista themselves are powered by a powerful torsion spring made of Malvolian Steel, as is the unrolling action of the bridge.
The ballistas fire heavy spiked bolts designed to pierce rock and metal and hold. Each bolt is connected to a heavy guide rope via a pulley on the back of the bolt. The ropes connect to a special reel at the base of the apparatus on one end, and the front of the plank bridge on the other.
Once both bolts are anchored, the operators pull a lever that engages a powerful spring to rapidly reel in the ropes, pulling the rolled bridge out across the gap. The reels are then locked into place for foot traffic to safely cross.
While the anchored bolts can safely support the weight of many laden individuals at once, it is recommended by the Givers and the Malvolian Seekers that the ends be separately anchored by another means if the bridge is intended to be permanent, or if heavy cart traffic or other beasts are expected to cross.
The ballista-bridge devices are created in such a way that the bridge reel is detachable, to facilitate easy transport and continuous use. Resetting the powerful springs requires the use of a ratcheting lever arm, and about 5 minutes of constant work. While tiring, these devices can be operated by a single individual, though weighing nearly 150 lbs, they are often too much of a burden for all but the strongest to transport on their own.
The maximum effective range of a ballista-bridge is approximately 150 feet. Use at further distances runs the risk of the anchoring bolts not properly securing themselves into their target far enough for safe operation. If a softer material is targeted than rock, the distance can increase out to approximately 300 feet, which is the effective limit of the spooling spring.