If you're asking what’s the best anchor system for a street bench on asphalt, the short answer is: don't rely on anchors screwed directly into asphalt. Asphalt softens in heat, flexes under load, and doesn't hold wedge anchors or sleeve anchors well over time. A permanent street bench should be anchored to concrete below or through the asphalt.
The system I recommend is a concrete footing or pad with cast-in-place or post-installed anchor bolts. Here's the practical setup:
1. Cut a neat square or rectangle in the asphalt where the bench legs will sit. Dig down about 12–18 inches, or below your local frost depth. Pour a 3000 psi concrete pad and set four 1/2-inch or 5/8-inch hot-dip galvanized or stainless steel J-bolts or L-bolts in the wet concrete. Use a plywood template so the bolts exactly match the bench base plate.
2. After the concrete cures, set the bench base over the bolts. Add flat washers, lock washers, and vandal-resistant nuts. Torque them down. This gives you a rock-solid connection that won't loosen as asphalt moves.
3. If you already have asphalt and cannot cut it, use helical ground anchors or screw piles driven through the asphalt into stable soil. Mount the bench on a base plate with leveling nuts so you can adjust for settlement or asphalt creep.
4. If the bench is temporary or very light, you can use epoxy anchors made for asphalt with a wide base plate. But check them seasonally because asphalt will flex and the holes can enlarge.
So the best anchor system is really a concrete-embedded anchor bolt system under the asphalt. For existing pavement, helical ground screws are the next best thing. Either way, avoid bolting directly into asphalt as the primary long-term hold.