Accurately locating ashtrays on a map is important to analysis of street ashtrays and their effect on smoking behaviour.
According to the Food and Environmental Hygiene department, the government provides 16,000 litter bins with/without ashtrays in Hong Kong (with no breakdown of how many of those bins have ashtrays) and about 1,800 dedicated cigarette bins. However, FEDH does not have geographical data on their location.
With an absence of official data, we wished to record ashtray positions and start building a database.
We selected Queen’s Road Central (QRC) as our first target to collect street ashtray data. QRC is a busy pedestrian and traffic thoroughfare running along the northern part of Central District, and is a quite typical Hong Kong road.
We used the GIS Cloud collaborative mapping platform (www.giscloud.com) to create a survey form to collect position data on the following:
1. Ashtray type
a. Food and Environmental Health Department (FEHD) litter bin ashtray
b. Dedicated FEHD ashtray; and
c. Other public ashtray.
2. Position and time
d. GPS accuracy
This survey was accessed through the GIS Cloud Mobile Data Collection (MDC) app, running on an iPhone 5, which allows automatic collection of Position and Time data. The user only has to mark the type, check the location, and press “Send” to collect the data point. (see figure 1)
Where GPS accuracy was more than 10m, or where the GPS location appeared to differ from the actual position viewed by the user, the “Pinpoint” feature was used and the data point marked manually.
We walked from the eastern end of QRC along the more southerly sidewalk of the road and then back from the most western end along the more northerly side. We restricted data collection to only QRC ashtrays and those accessible from the street on open areas (eg building plazas).
After the field collection, data was accessed through GIS Cloud’s online platform and exported to Comma Separated Variables (CSV) format, and then imported into Google My Maps as a layer. Data points were styled according to the “ashtray type”.
We recorded 63 ashtrays along the route.
The route measured as total 3.09 km (1.54km northerly sidewalk and 1.55km southerly sidewalk).
This translates as, on average for QRC, one ashtray every 49 metres.
|Litter bin ashtray||46|
|Dedicated FEHD ashtray||4|
The map of the measurement is shown in Figure 2.
Discussion on the technique
It was found the GPS measurement was quite inaccurate, around 20-30m in most cases, and we were required to manually pinpoint all data points. We will consider this could be down to
- difficulties in using GPS in Hong Kong’s environment, where many tall buildings surround the streets and restrict satellite view; and
- quality of the technology employed (eg iPhone 5).
We will investigate other data collection methods to improve speed, as manually pinpointing each data point is time consuming.