That's an excellent and very practical question. The short answer is: it depends heavily on your crew's specific skills, the project's complexity, and your long-term maintenance goals. Many public works departments are fully capable of installing standard, in-ground benches, especially if they have experience with concrete work and standard municipal fixtures.
For straightforward installations on level, stable ground using pre-cast concrete feet or direct-set posts, your trained crew can likely handle it efficiently. This approach offers cost savings and faster deployment. However, professional installation is strongly recommended for several scenarios: installing heavy or complex designer benches, working on challenging surfaces like brick pavers or slopes, requiring specialized anchoring for high-vandalism areas, or when liability and warranty concerns are paramount. Professionals ensure perfect leveling, use commercial-grade equipment, and often provide a guarantee on their work.
Consider a hybrid approach. Use your crew for routine, simple replacements in low-risk areas. Hire professionals for high-profile civic spaces, complex foundations, or large batches where speed and guaranteed quality are critical. Always prioritize safety, correct foundation depth, and ADA compliance regardless of who does the installation. Assess your team's current workload and specific bench design before deciding.