What does the Directional Design Hour Volume (DDHV) equation calculate?

What does the Directional Design Hour Volume (DDHV) equation calculate?

• A. DDHV = AADT / K
• B. DDHV = AADT - K
• C. DDHV = AADT * K * D
• D. DDHV = AADT + D

Answer: (C)

The Directional Design Hour Volume (DDHV) equation is crucial for traffic engineering as it helps in determining the volume of traffic expected during the busiest hour in a given direction. This calculation is particularly useful for designing roads and intersections to accommodate peak traffic conditions. The correct formulation for DDHV is derived from the Average Annual Daily Traffic (AADT), which represents the average traffic volume over a full year, and the peak hour factors, K and D. Specifically, the equation DDHV = AADT * K * D connects these variables, where K is the portion of the daily traffic that occurs during the design hour, and D represents the directional distribution factor, indicating the proportion of traffic that travels in the specified direction during that peak hour. Understanding this relationship allows engineers to estimate the maximum traffic flow and make informed decisions about road capacity, lane configurations, and traffic signal timings. The variables involved cater to the differences in daily and hourly traffic volumes, enabling more specific and reliable designs tailored to realistic traffic patterns. Other formulations do not accurately express the relationship necessary for calculating the DDHV, as they either misrepresent the interaction of average daily traffic and its peak hour characteristics or fail to include the adjustment for directional distribution.

The Directional Design Hour Volume (DDHV) equation is crucial for traffic engineering as it helps in determining the volume of traffic expected during the busiest hour in a given direction. This calculation is particularly useful for designing roads and intersections to accommodate peak traffic conditions.

The correct formulation for DDHV is derived from the Average Annual Daily Traffic (AADT), which represents the average traffic volume over a full year, and the peak hour factors, K and D. Specifically, the equation DDHV = AADT * K * D connects these variables, where K is the portion of the daily traffic that occurs during the design hour, and D represents the directional distribution factor, indicating the proportion of traffic that travels in the specified direction during that peak hour.

Understanding this relationship allows engineers to estimate the maximum traffic flow and make informed decisions about road capacity, lane configurations, and traffic signal timings. The variables involved cater to the differences in daily and hourly traffic volumes, enabling more specific and reliable designs tailored to realistic traffic patterns.

Other formulations do not accurately express the relationship necessary for calculating the DDHV, as they either misrepresent the interaction of average daily traffic and its peak hour characteristics or fail to include the adjustment for directional distribution.