Open a catering business that focuses on construction sites. Mobile food trucks deliver a variety of prepared food such as breakfast items, sandwiches, snacks and drinks. You can own and operate a catering truck on a part-time or full-time basis depending on your schedule. With little overhead and marketing costs, you can start running a successful construction site catering business in very little time. Purchase a truck and obtain the licensing needed to sell food to get started.

Apply for a business license to start a catering business for construction sites. Contact your local small business administration office or county clerk's office for more information. Apply for an employer identification number (EIN) from the Internal Revenue Service (IRS) if you hire workers. Use the EIN on state and federal tax forms, business registration forms and other business documents. Register your catering business with the secretary of state's office in your state to form a limited liability company (LLC), corporation or partnership. Apply for a sales tax number from your state's department of revenue office to collect sales tax from customers.

Contact your local health department for food retail and distribution licensing requirements. Licenses may be required for food managers, food handlers and food distribution. You may have to complete training and pass an exam to qualify for a license.

Buy a new or used catering truck. Carefully inspect the truck to ensure it is in good condition. Most catering trucks have enough space to store and prepare food. Some trucks include small appliances such as refrigerators and microwaves. Contact the health department to schedule an inspection of your catering truck.

Determine the types of foods to sell from your catering truck. Food items may include hot and cold lunches, sandwiches, snack foods and drinks. Contact local restaurants and schools to find a place to prepare these foods. Many public institutions rent kitchen space to caterers and others in the food retail business. Contact the health department if you want to prepare food at home to determine if additional licensing and inspections are needed.

Design a route for your catering business that includes stops at construction sites not yet over-served by other food wagons. Determine the amount of time needed to stop at various construction sites in your area and which times of day--for instance morning, early afternoon or late afternoon--are likely to generate the most business.