Permanent Wooden Wheelchair Ramp Build at Front Entrance

We need a permanent, ADA-inspired wheelchair ramp built at the front entrance of our single-story home to replace the current three-step entry, which is no longer safe for a family member using a manual wheelchair. The ramp must follow a safe slope ratio of 1:12 — one inch of rise for every twelve inches of run — which for our roughly 24-inch entry height means the ramp run needs to be approximately 24 feet long, likely arranged with a switchback or L-shaped turn to fit our yard, connected by a level landing platform at the turn measuring at least 5 feet by 5 feet so a wheelchair can rotate fully. A second landing platform of the same minimum size is required directly at the doorway threshold, flush with the interior floor level to avoid any lip or gap. Continuous handrails are needed on both sides of the ramp, mounted at 34 to 38 inches high, with a secondary lower rail if possible, plus edge curbs at least 2 inches tall to stop wheels from slipping off. The surface material should be pressure-treated lumber or composite decking with a textured, non-slip finish rated for wet weather, since our climate has frequent rain. Proper footings are essential: concrete piers set below the frost line, with joists and posts rated for outdoor load-bearing use and a structure that can support at least 600 pounds of moving load plus static weight. We would like the contractor to pull any required local permits, provide a materials list, and give a realistic timeline from groundbreaking to final handrail installation, ideally completed within three to four weeks. Please share examples of similar ramps you have built, your approach to drainage under and around the ramp, and an itemized cost estimate before starting.