The trail was never easy to find, but now it's much more difficult unless you know the secret. Drive south on Highway 93 3.1 miles past the Welcome to AZ sign and turn left on the signed White Rock Trailhead Access road. Get back on Highway 93 heading north for 0.5 miles and park just before the bridge in the photo. This is the only way to park on the east side of the road, which has lots of parking as you can see in the photo.
Currently, this bridge is unsigned and there's NO vehicle access, no roads lead up to the bridge. Walk up the steep embankment and cross the bridge. You are now on the west side of the highway. The trail for Liberty Bell Arch is about 100 yards to the south. There's no path to follow. Just parallel the highway until you come to a gravel road. This is the start of the trail that leads to Liberty Bell Arch. Simply turn right (west) and follow the trail. Hikers familiar with the old trail and trail will recognize this gravel road.
Cross the bridge in the photo and head west down into a wash. The wash soon becomes more defined. Follow the wash until you are across from Liberty Bell Arch, which is visible and much more dramatic looking from this angle. Head cross country toward the arch soon dropping into a class 2 wash. Follow the wash to the bottom of a ridge. Hike up to the top of the ridge where you intersect the trail. This route is much shorter, but you bypass the mine the normal trail goes by.
Option 3: Drive south on Highway 93 3.1 miles past the Welcome to AZ sign and turn left on the signed White Rock Trailhead Access road. Follow the road a short distance to the paved parking lot for AZ hot springs. Follow an unsigned hiker's path under the highway to the AZ Hot Springs Trailhead sign. Follow the wash (the official trail is actually 100 yards south) about .66 miles to the intersection with an old jeep trail. Head north (right) on the jeep trail about .75 to the intersection of the Liberty Bell Arch trail.
This way is much longer and somewhat boring.
I am sure some of these options will change. There's more construction to be done on the bridge. I saw fencing on the ground and there are cameras installed on the bridge. I have no idea what that's about.