Global Street Design Guide Design Controls Design Hour

Global Street Design Guide

Design Hour

Streets function differently at different times of day, at different times of year, and over longer periods of time. The pace and flow of life varies in each city as does the use of public streets. Streets expand and contract with people, vehicles, vendors, cafés, markets, and crowds throughout the day and week.

Design streets to provide comfortable capacity during a typical hour of the day, instead of just the peak hour. The typical hour is often the average between activity levels during peak, late night, midday, and weekend hours. This allows planners to balance safety with the needs and functions of the street at different times.

Design Hour, or activity levels during an hour, is used to determine the appropriate street dimensions. The traditional practice of using a single peak hour volume and projected volume increases allows traffic volumes to dictate the construction of costly infrastructure, without determining how much traffic is desired on a street.

Rather than creating infrastructure to be used for just a few hours each day, consider the average activity levels of a street by analyzing multiple hours for a clearer picture of demand. Building unnecessary capacity may be expensive. The cost varies widely based upon land ownership, terrain, and prevalence of other variables.

By proactively setting the capacity for motorized vehicles, Design Hour can also be used to guide the amount of traffic a street will accommodate, and organize the street so that it can support a balance of many different users.

Critical Guidance

Base operational decisions on unbiased quantitative measures that consider overall community metrics and the many functions a street must serve, including safety, supporting local businesses, providing access to jobs and services, and environmental targets. See: Measuring and Evaluating Streets.

Recommended Guidance

Expand the Design Hour analysis to include the various peak hours throughout the week for all users. Analysis might include a morning peak, midday peak, afternoon peak, and weekend peak hour. Study these peaks to obtain a more nuanced understanding of travel, resulting in a design better suited to the actual street usage.

Account for all street uses over 24 hours and 7 days. This includes rush hour commuting in all mobility modes, evening strolling, weekend markets, lunchtime dining, and commercial deliveries. Mapping these static, mobile, existing, and expected activities provides a temporal snapshot of the street that can be used in design.

Use person-trips, rather than vehicletrips, to determine capacity. Trip generation manuals that consider only vehicle trips, or rely on small samples from suburban locations, should be avoided.

Transportation demand management describes programs that seek to shift travel mode, typically away from single-occupancy vehicles. People are encouraged to take transit, walk, cycle, not make the trip, combine trips, or travel at different times of day. These programs are more cost-effective than capacity expansion. See: Operational and Management Strategies.

AM Peak: Signals are adjusted to accommodate rush-hour traffic during the peak hour, metering traffic to prevent gridlock.

Midday: Downtown pedestrian volumes reach their peak intensity at lunch hour.

Evening: Traffic volumes begin to dip after rush hour, while pedestrian traffic in certain areas rises.

Adapted by Global Street Design Guide published by Island Press.