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Modern Geomatics Technologies and Applications

Fig. 2. Air pollution map of particles less than 2.5 microns in diameter
Environmental Characteristics Data: In this study, to measure environmental characteristics, we employed road network,
demographic data, crash location data (for 2016), slope map, bus stations and land use map. The study used road network data
extracted from the OSM website. The Strava Metro Suggested Roads Network has higher coverage and detail levels than
Glasgow's official road data. To assess the safety of the road network, the 2016 crash data provided by DATA.GOV.UK was
used. Aster sensors elevation data for the Glasgow city area were used to produce the slope map. Scotland's 2011 census data
were also used for population and employment data and population and employment density along each street were calculated.

2.2. Inhalation of Air Pollution During Active Trips
Inhalation of air pollution depends on the amount of environmental pollution and the duration of the trip. To evaluate
exposure to air pollution during bicycle trips, the total amount of inhalation of pollution is calculated for all trips in the whole
year. Then the average amount of inhaled pollution is calculated for each trip. As the road network is divided into two sections
of street and intersection, to calculate the total amount of pollution, the amount of inhaled pollution must be calculated at the
waiting time at intersections, as well as the amount of inhaled pollution during the moving along the streets. The amount of
inhalation air pollution during waiting at the intersection is obtained by Eq. (1) and (2).
(1)
_ ( ) = ∑ _ ( , ) × _ _ ( , )

_ ( ) = _ ( ) × × _ ( ) × (2)

In Eq. (1), num_act(i,t)and Med_time_wait(i,t) show the number of trips and the average stop time at the intersection i at
time t, respectively. In Eq. (2), Air_pollution represents the contamination value at the points i. Cbike and VR show the
conversion factor and the ventilation rate which are 2 and 2.55 for cycling respectively.
The following relationships are used to obtain inhalation contamination while traveling along the streets:
(3)
_ ( ) = ∑ _ ( , ) × _ _ ( , )
_ ( ) = _ ( ) × × _ ( ) × (4)
The total amount of inhaled pollution is equal to the sum of inhaled pollution at the intersections and on the streets.

2.3. Analysis of the Impact of Environmental Parameters on Active Trips
Regression was used to investigate the impact of environmental characteristics including socio-economic, road network and
land-use factors on cycling (Table 1). For this purpose, the rates of commuting trips and non-commuting trips were calculated
for each street as a dependent variable. To investigate the effect of time on bicycle trips, the travel start time parameter is used
and the time during the day is classified into four-time windows including the morning (6 to 10), noon (10 am to 4), afternoon
(16 to 19) and night (19 to 22). Also, by using the census data, employment density and population density were calculated
along each street. The length and slope of each street were considered to evaluate the impact of the road network. Also, the
street types were categorized into minor and major streets. To assess the safety of the road network, the number of crashes was
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