In my current and previous internship experiences, I have had the opportunity to work with transportation engineers and planners across the state. Specifically, I have had experience with estimating trip generation and trip distribution. The company I work for now, a traffic and design engineering and planning firm, is hired by private companies to determine if adequate traffic flow is accommodated and is functional with the surrounding community. The project planners and engineers determine trip generation and distribution estimation, based on statistics from similar vendors in the area. In the reading, the trip generation and distribution estimations are seen from more of a planning perspective. Although the engineers do follow the Four-Step Process, it is not exactly the same, being seen from an engineering stand point. By viewing other companies (such as Wendy’s or Home Depot) vehicular production in the area are, engineers can closely estimate trip distribution for the Taco Bell, or whoever else is hiring them. Planners then look at networks of these smaller projects and see the impact on a larger scale.
In order to come up with certain values and trip numbers, project managers and planners obtain raw data. Other information the engineers desire are speed limits, abnormal conditions, and cycle length (in cases where traffic signals are present). Cycle length is composed of the total signal time to serve all of the signal phases including the green time plus any change interval, including yellow and all red time. Longer cycles will accommodate more vehicles per hour but that will also produce higher average delays for other phases. These are important parameters that are taken into account for planners to make large scale decisions.
While working for the NJDOT, I was involved with planning of construction maintenance yards across the state. Maintenance yards are where all the construction equipment and tools are stored, including the trucks used to transport them to the sites. I worked closely with safety inspectors to investigate safety concerns within the maintenance yards. These investigations varied from construction vehicle damage to structural damage of salt garages. These inspections were essential to making state construction projects as efficient as possible. Planners may base projections on how well construction management is handled and which company is doing the management.