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Connecting the city

3D pedestrian network of Hong Kong

Physical connections

A three-dimensional pedestrian network is crucial for Hong Kong. Government authorities, international consulting firms, and urban researchers love to talk about walkability. When it comes to the high-density city, unfortunately, their analyses are wrong. Besides miss-conceptualisations of walkability for Asian contexts, usually, from European and North American experience, they also use wrong data. Pedestrians walk on the three-dimensional (3D) networks, such as the footbridges and undergrounds. But the city does not have such data in the past, so people use the road network as a substitute.

We built the 3D pedestrian network of Hong Kong, in three years, from 2016 to 2019. Our 3D pedestrian network model classifies segments into 23 categories with multi-height levels, such as sidewalk, footbridge, underground, crosswalk, ramp, paths on the building roof. We built the data using a geographic information system. The 3D pedestrian network is over 8000 km, which is 2.4 times in length and 8.5 times in link size greater than the road network.

Figure 1. Comparison between the pedestr

Everyone can freely download and use the data (government data portal). Our network data have been transferred to Lands Department through HKU Technology Transfer Office, and released to the public recently. The accurate data empower urban analytics of the high-density city. Now we have the correct data, walkable Hong Kong and smart-city applications can do better.

Our 3D pedestrian network work has won two prestigious awards from Royal Town Planning Institute (RTPI) in 2019, the early career academic award and commendation award for research excellence.

A teamwork with

Prof. Chris Webster, Dr. Xiaohu Zhang, Alain JF Chiaradia, Jianting Zhao, Dugald Wallace, Xiaoyang Nan, Yanan Zhang, Meng Yuan, Jiaxuan Yang, Shaochao Wang, Xiaodong Shi

RTPI awards_gsun_Page_1.jpg

How to cite:

G. Sun, C. Webster, X. Zhang, (2019). Connecting the city: A Three-dimensional Pedestrian Network of Hong Kong. Environment and Planning B: Urban Analytics and City Science, 1-16. 


A sustainable future

What if gated communities became permeable for walking and cycling?

China’s city is the leader in building gated communities. A recent policy was seeking to open them. We use permeability analysis to explore the ‘what if?’ question posed by the policy: what if gated communities became permeable? We ask the question in respect of non-motorised access, not for cars as the ungating policy implied. Nanchang, a medium-sized Chinese city with over 600 large gated communities, is the study area. We constructed a bespoke complete pedestrian network, for the permeability modelling. The ungated pedestrian network is 18 times longer than the gated road network.

Based on permeability models, we sequentially sort the gated compounds whose opening will maximise permeability gains with minimum property rights expropriation through coercive ungating. We offer the analysis to urban scholars, planners and governments by way of a quantified simulation. Reconfiguring the gated form promotes healthier living environments - more walking and cycling, more economically viable cities - greater pedestrian footfall concentrations, and a sustainable future.

How to cite:

G. Sun, C. Webster, A. Chiaradia (2018). Un-gating the cities: A permeability perspective. Urban Studies, 55(12), 2586–2602,

Figure 1. gated communiteis types.jpg
Figure 2. The workflow of the walkabilit


Walkability scoring

Striking underestimated in Asian high-density cities

Figure 3. Walkability scoring difference

A standardised measurement makes walkability easily studied analytically and across various disciplines. Attempts to create walkability measures started in the 1990s, with increasingly sophisticated composite walkability indices being proposed in the past decade. One that gained wide attention is Walk Score, which is developed by a group of planners and urbanists and provides standardised walkability evaluations. Leveraging on web and amenities data, Walk Score evaluates a great number of cities in the USA, Canada, Australia and New Zealand. The ready-to-use scoring data and algorithms permit extensive evaluation by practitioners and researchers without their own modelling capacity. 

However, Walk Score data are not available to Asian cities. Superimposing its default algorithm to unsupported regions would yield inaccurate and unreliable measures, as Asian cities tend to be denser, and pedestrian networks differ from road networks. We constructed a walkability scoring system using amenities data and a 3D digital pedestrian network for Hong Kong. The same algorithm was applied to the regular road network in order to analyse how the scoring was underestimated. 

Our results show that streets were considered twice as walkable if rated by the pedestrian network rather than the road network. Walkability scores were 92% higher on average. 

How to cite:

J. Zhao, G. Sun, C. Webster (2020). Walkability Scoring: Why and how does a 3D pedestrian network matter?  Environment and Planning B: Urban Analytics and City Science  

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