“Design for Mobility Route”
Public transit (Tram) network design and accessibility evaluation
Site: Tallinn, Capital of Estonia
Method: Accessibility analysis for multi-modal mobility (Reach and Gravity)
Date: 2016, GSD Advanced Seminar in City Form
Reach and gravity analyses on the current tram system at both city and site scales helps to find out the most desirable stops, and post-design quality.
At the city scale, a Reach analysis unfolds how many lines can reach buildings within 600m. The outcome shows the current network connects well the old town and its periphery areas that had been developed. Most accessible spots are located in the east of the Old Town. (Here, some but not many of the buildings could get to the maximum number of lines, 14) Areas that to be developed like Tallinn Port and highspeed train station are less served. Though the airport can be reached by tram, passengers need to walk more than a half-mile or transfer to another means to get to the entrance of the terminal which is inconvenient.
The proposed network increased 1200 buildings that can reach one or more tram lines within a 600m radius. In this chart, the x-axis is the number of buildings and the y-axis is the number of lines a building can reach. We see it also increased the proportion of buildings. For example, the proportion of buildings that could reach more than 6 lines, even though the maximum number of lines a building can get to is decreased from 14 to 12. The change of spatial pattern of the tram network on the map, unlike the current distribution of tram stops and lines, creates multiple spots that have higher accessibility most of which are close to critical areas of the city (such as CBD, port, and old town, also the transportation hubs including future highspeed rail station).
A Gravity analysis unpacks the relative attractiveness of buildings to get to tram lines regarding the travel cost. From this chart, more buildings have better accessibility in our proposal, especially those with attractiveness rates between 1.5 to 3. The spatial pattern of accessibility to the tram follows the outcome in reach analysis.
At the site level, the proposed tram improves accessibility even more. If we add new tram stops on our proposed port build form. The total number of buildings that could reach one or more lines increased from 2085 to 2307. The maximum number of lines a building can get to remains. The proportion of buildings that can reach more than 6 lines is nearly doubled. Spatially, the new tram system covers every corner of the site by acceptable distance from the stations and buildings proposed.
The Gravity analysis proves more equal accessibility of tram stops. Although the maximum rate of attractiveness is decreased in the proposal, the proportion of buildings with attractiveness between 0.5 and 3 increased.
In general, the accessibility will increase in critical areas at both city and site scales. I think the proposal could connect better the developed or to be developed areas and offer convenient access to different sub-areas. The followings are about tram system design details.
