Trip generation of retail developments in Singapore

Institute of Transportation Engineers. ITE Journal, Sep 2001 by Fan, Henry S L, Tan, Yan Weng

Eight retail sites were finally selected. Geographically, four sites were located within the CBD and four outside. Major arterial roads as well as the public bus system served all the sites. Each of the sites in the CBD had at least one MRT station located within 500 meters (m) of the site. On the other hand, MRT stations were usually quite some distance from sites outside the CBD. Therefore, these sites were not within easy walking distance of a fast, convenient and air-conditioned public-transport system.

TRAFFIC SURVEY

Trip data were collected by manually counting all vehicles that contributed to traffic demand at each site, summarized in 15-minute intervals. These included vehicles that used the on-site carpark, or parked along adjacent streets when on-- street parking is available within a 100-m [328-feet (ft.)] walking distance of the site, vehicles dropping-off or picking-up passengers at the site, as well as vehicles loading or unloading goods at the site. The total peak-hour trips generated can be determined by combining the drop-- off and pick-up traffic, loading and unloading traffic, and the arrival and departure of vehicles to and from the site.

As shopping activities in Singapore tend to peak on weekends and most retail developments are open for business from 10 a.m. to 10 p.m., traffic surveys were conducted during this 12-hour time period on Saturdays and Sundays at the selected sites. The traffic composition consisted of about 60 percent cars, 20 percent taxis and 20 percent other vehicles (goods vehicles and motorcycles).

SITE CHARACTERISTICS

Survey questionnaires were mailed to the building management of all selected sites to obtain information on site characteristics such as the nature of business of their tenants, parking charges for the first hour, gross floor area (GFA) and gross leasable area (GLA). The difference between GFA and GLA is that GLA is the floor area available for tenant use. Note that floor areas of internal carparks were excluded in both GFA and GLA. In addition, the straight-line air distance from each site to the nearest MRT station was also measured.

The results of the building management and traffic surveys are summarized in Table 1. The GFAs of these sites showed a good spread, varying from 12,577 m^sup 2^ to 94,652 m^sup 2^. At least 83 percent of the tenants in the study sites engaged in retail business. Since the sites had at least 95 percent occupancy level at the time of the survey, trips generated would be close to peak demand levels. Overall, most parameters recorded a reasonable degree of variation about the mean, with coefficients of variation (CVs) ranging from 0.59 to 0.84. The exception was hourly parking charges for the first hour, which did not vary much across the sites (CV = 0.33), and was not likely to be a suitable explanatory variable.

TRIP-GENERATION ANALYSIS

Two methods were used to estimate vehicle trips generated at retail developments: weighted average rate and regression equation.

WeightedAverage Tip Rates