Safe Routes Scoop

Transportation Engineering Design Manuals: What They Do

are all covered within the RDM. The manual is also utilized by county public works departments in their own roadway design and construction projects.


Additionally, the RDM includes design standards for pedestrian and cyclist

rights of way, and the management of pedestrian and cyclist movement alongside motor vehicles, and across motor vehicle rights of way. These standards include signage for shared use paths, recommended shoulder widths to accommodate cyclists, and guidelines for reconstructing roadways to enhance pedestrian safety.


What is the HCM?

The Highway Capacity Manual (HCM) has been a primary resource for nearly 60 years for measuring roadway capacity, or the degree to which roadways meet traffic demand. In addition, the HCM provides tools to gauge how transit, pedestrian, and bicycle demand impacts the quality of service of roadways and their ability to provide efficient and safe transportation.


The manual addresses traffic congestion by offering a way to quantify congestion and highway operations so that conditions can be clearly understood and effective solutions can be developed. To keep pace with changing travel characteristics and improvements in capacity analysis, the HCM has been updated several times since its first

edition in 1950. The most recent edition is to be released by the end of 2010.


What is Trip Generation?

The Trip Generation Report is compiled by the Institute of Transportation Engineers (ITE) and is used to forecast travel demand, using

models to predict how much traffic will enter and exit a particular traffic analysis zone. The report presents trip generation statistics, showing peak travel rates and the hour of day at which they occur. The resulting ratios are categorized by surrounding land uses and building types; the 2010 version includes data for 162 distinct land uses. The data serve a variety of uses for transportation professionals, from calculating local traffic patterns to planning the appropriate use of various traffic safety devices.


What is Parking Generation?

Another ITE product is the Parking Generation Report which measures demand for parking according to the time of day. As with trip generation data, the parking demand data is categorized by land use, as different uses present different parking needs and patterns. For example, a school is likely to experience its peak parking during weekdays, while entertainment complexes are most likely to experience peak demand during weekends. With this data, planners can discern the time of day when parking demands are greatest for a particular land use, and can compare

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