Zip Line Planning Overview
A zip line begins with geometry. The span sets the main cable length. The height difference sets the natural speed. Sag affects tension more than most beginners expect. Small sag creates high cable force. Extra sag lowers force, but it also reduces clearance. This calculator joins these checks in one worksheet.
What The Inputs Mean
Enter the horizontal span, starting height, ending height, and desired clearance. Add sag as a percent of span. Include cable mass, rider mass, trolley mass, wind load, and dynamic factor. These values create a conservative design picture. They do not replace engineering.
Reading The Results
The tool estimates slope, cable length, midspan clearance, and support reactions. It also estimates horizontal tension by using a parabolic cable model. The anchor force includes wind reaction as a separate side load. The required breaking strength multiplies this force by your chosen safety factor.
Speed And Braking
Speed is estimated from vertical drop and ride efficiency. Real speed changes with friction, rider posture, cable angle, weather, trolley quality, and braking method. Braking distance converts peak speed into average stopping acceleration. High values need safer layouts, longer braking zones, or lower drop.
Practical Design Notes
Use the results to compare design options. Increase sag when tension is excessive. Raise platforms when clearance is too low. Reduce drop when speed is too high. Increase cable rating when the safety margin is weak. Check trees, towers, soil, anchors, clips, terminations, harnesses, rescue access, and inspections before any build.
Important Safety Reminder
Zip lines carry people. Loads can rise during bouncing, braking, wind, and sudden stops. Local codes may require permits, inspections, or certified designers. Always ask a qualified engineer or competent professional to verify the final plan. Use this page for early planning only.
Example Workflow
Start with a modest sag setting. Review the clearance result first. Then review tension and cable strength. Next check peak speed and braking acceleration. Change one input at a time. This makes each effect clear. Save the CSV for records. Export the PDF when sharing a concept with a contractor, site owner, or reviewer. Keep notes about assumptions beside every saved result. Never use estimates as permission to install a finished ride.