Lesson 3
When commuting becomes cheaper
In Lesson 1 a fall in the cost of commuting spreads the city outwards and flattens its rent gradient. This lesson asks how the cost of reaching the centre of Ho Chi Minh City has changed: through the spread of the motorcycle, through new bridges, a tunnel and expressways, and through public transport. The effect of each new road link on travel times is measured with a model of the road network.
Learning objectives
After this lesson you should be able to:
- state what the commuting cost \(t\) of the model stands for in a real city, and name the changes that can lower or raise it;
- explain how a network model isolates the effect of individual road links on travel times, and state what such a model leaves out;
- read a travel-time map and compare the maps of different years;
- explain why the same link can change travel times by car and by motorcycle by very different amounts;
- relate the changes to the comparative statics of Lesson 1, and say why the relation is an interpretation rather than a test.
3.1Commuting cost in the model and in the city
In the model of Lesson 1, commuting costs \(t\) per kilometre of distance, so a household living \(x\) kilometres from the centre spends \(tx\) on commuting. The comparative statics of the model state what happens when \(t\) changes:
Figure 1.2 lets you lower \(t\) and watch the city spread: rent falls at the centre, rises at the edge, and the edge moves outwards. In a real city the cost of a trip has two parts, money and time, and both depend on the means of transport. The cost of reaching the centre can therefore fall for three reasons: a cheaper or faster means of transport spreads, new links shorten routes, or public transport reaches more places. It can also rise, when traffic grows faster than road space. The rest of this lesson takes these in turn for Ho Chi Minh City.
3.2The motorcycle
No official series of vehicles or trips is published for Ho Chi Minh City. Table 3.1 collects the figures that sources report for a stated year. The World Bank described the city of the early 2000s, drawing on travel surveys by the consultants ALMEC, as follows:
Commuting was short by international standards:
| Year | Measure | Value | Source |
|---|---|---|---|
| million | |||
| million | |||
| million | |||
| million | |||
| million | |||
| million | |||
| million |
Source: as listed in each row; full references in Section 3.8. Figures from Vietnamese newspapers are quoted from the page, with the public body the newspaper cites.
Note: the rows come from different sources that do not define their measures in the same way, so they should not be joined into a single series. The public transport share of 2024 refers to travel demand as reported by the City People’s Committee; the shares of 2004 refer to trips. The script stops if a value no longer matches the sentence it is taken from.
Registered motorcycles rose from million in 2001 to million in 2023, a -fold increase. The source that reports the growth in motorcycles also reports what happened on the main roads:
3.3New bridges, a tunnel and expressways
Between 2008 and 2026 the city and the national government opened the links listed in Table 3.2. Before the Thu Thiem Bridge, most people crossing from District 1 to Thu Thiem used a ferry: the operator reported about passengers a day before the bridge opened and about a day afterwards, and the ferry closed once the tunnel had opened.
| Link | Opened | Source |
|---|---|---|
Source: government portals and newspapers named in the table, with the date of each report; links in Section 3.7.
Note: each date is accepted only if the report, downloaded and kept with the data, contains the sentence that states it and carries the date of publication given here; the script stops otherwise. Pham Van Dong Avenue was opened in sections over several years and is treated as opening in 2015.
To see what these links did to travel times, Map 3.1 uses a model of the road network. The network is the one mapped in OpenStreetMap in September 2026. For each earlier year, the links of Table 3.2 that had not yet opened are removed, and the Thu Thiem ferry is put back until 2012. The time from every road junction to Ben Thanh is then the shortest route over the network, at speeds assumed for each class of road. Motorcycles may not use expressways, and OpenStreetMap records some bridges, such as the Phu My Bridge, as closed to them; the model therefore finds a separate network for each mode.
Modelled minutes from each 500 m cell, without congestion
The network of . From District 1, Thu Thiem is reached by the ferry or by road over the Saigon Bridge, and there is no expressway. Hover over the map to read the time from a cell in each of the four years.
The network of . The Thu Thiem Bridge, the Phu My Bridge and the expressway to Trung Luong have opened. Switch between motorcycle and car: the Phu My Bridge and the expressway serve only cars.
The network of . The Thu Thiem Tunnel and Mai Chi Tho Avenue replace the ferry, and the expressway to Long Thanh and Dau Giay reaches the former province of Ba Ria–Vung Tau. By car, Vung Tau ward is minutes from Ben Thanh on the network of and minutes on this one; by motorcycle, minutes on both.
The network of . Ba Son Bridge, the expressways from Ben Luc to Long Thanh and from Bien Hoa to Vung Tau, and the open sections of Ring Road 3. Choose “Minutes saved” to see where the links of the whole period changed the time to Ben Thanh.
Source: road network © OpenStreetMap contributors (ODbL), extract of 16 September 2026 by Geofabrik; opening dates as Table 3.2; model by kich_ban/l3_thoi_gian_di_lai.py; base map OpenFreeMap.
Note: the model removes only the links of Table 3.2; every other road is as mapped in 2026, including roads built after the year shown, so the maps of earlier years understate travel times. Speeds are assumed for each class of road and do not change over time; congestion is ignored. Cells without a mapped road are left blank. Six communes at the eastern end of the former Ba Ria–Vung Tau province, beyond the area of the model, and the island commune of Thanh An are not covered.
How close are the modelled times to real ones? A report by VnExpress in 2026 published motorcycle travel times to Ben Thanh station for small hexagonal cells, also computed without congestion. Across the cells that the two sources share, the correlation between the two sets of times is , so the model ranks places in the same order; the VnExpress times are longer by a median factor of , because the two sources assume different speeds. The minutes on Map 3.1 are therefore best read as comparisons between years and between places, not as the time a commute takes.
3.4Who gained
For motorcycles, the links of the whole period mattered in one part of the city only. On the network of , wards are at least five minutes closer to Ben Thanh than on the network of , all on the eastern bank of the Saigon River and reached through Thu Thiem. The largest gain is in , from to minutes. After , no ward gains five minutes by motorcycle: the new links are expressways.
For cars the picture is different. wards and communes gain at least five minutes between and , and more between and . The largest gains in both periods are more than 50 km from Ben Thanh, in the former province of Ba Ria–Vung Tau, which the expressways connect to the city. Figure 3.1 sums the change as the area of land that lies within 30 and 45 minutes of Ben Thanh.
Area of 500 m cells with a mapped road, km²
Source: as Map 3.1.
Note: dashed lines are model output. Thick lines: within 45 minutes; thin lines: within 30 minutes. The network of each year is that of 2026 without the links opened later, so the growth shown is the effect of the links of Table 3.2 alone.
Within 30 minutes of Ben Thanh, the model reaches km² by car on the network of and km² on that of ; by motorcycle, and km². In the language of Lesson 1, the links lowered \(t\) far more for drivers than for motorcycle riders, who made most trips.
3.5Public transport
Buses carried about million passengers a day at their peak in 2012 (Table 3.1). In 2023 they carried million in the whole year, and public transport met of travel demand in 2024. Metro Line 1, from Ben Thanh to Suoi Tien, opened on ; in its first year it carried million passengers, about a day.
Map 3.2 measures what the bus network and the metro offer a commuter. It uses the weekday timetables published by the Public Transport Management Centre, which include Metro Line 1: in the timetable of September 2026 a train takes minutes from end to end and leaves every minutes between 7 and 8 am, more often than the 8 to 12 minutes reported when the line opened. “Bus only” is the same network without the metro. For each square kilometre within 30 km of Ben Thanh with a stop nearby, it finds the fastest journey to Ben Thanh for departures at 7:00, 7:15, 7:30 and 7:45 on a weekday morning, including the walk to the stop, the wait and any change, and averages them.
Modelled minutes from each 1 km cell, average of four departures between 7:00 and 7:45
Source: bus routes, stops and trips from the public service of the Ho Chi Minh City Public Transport Management Centre, assembled for this course on 5 September 2026; metro stations and track © OpenStreetMap contributors; opening timetable as reported by VnExpress (22 December 2024); model by kich_ban/l3_cong_cong.mjs.
Note: the service publishes only the start and end time of each bus trip, so the time at each stop is interpolated along the route, and traffic delays are not included. Walking is at km/h, up to m to a stop, with at most changes. Cells without a stop within walking distance are blank.
Within 45 minutes of Ben Thanh, public transport reaches km² by bus alone and km² with the metro; within 60 minutes, and km². The metro shortens the journey by ten minutes or more over km², and by up to minutes: km² of this lies within 3 km of a station, and the rest farther out, where a bus takes riders to the line. Compared with the motorcycle times of Map 3.1, public transport remains slow: within 10 km of Ben Thanh the median journey takes times as long, and between 10 and 20 km times as long. For most households in the city, \(t\) is still set by the motorcycle.
The same VnExpress report gives bus times to Ben Thanh station for these departures. Across the cells the two share, the correlation is and the median ratio of their times to ours is .
3.6Exercises
Exercise 3.1Cheaper commuting in the model
Use Figure 1.2 of Lesson 1. Move the slider for commuting cost to the left and describe what happens to rent at the centre, rent at the edge and the position of the edge. Which of these changes would you expect to see first in a city where only one corridor became cheaper, and why?
Exercise 3.2Motorcycles and cars
On Map 3.1, choose “Minutes saved” and switch between motorcycle and car. Name two places where the two modes gained very differently, and explain the difference with Table 3.2 and the note under Map 3.1.
Exercise 3.3What the network model leaves out
The model keeps every road other than those in Table 3.2 as it was in 2026, assumes constant speeds and ignores congestion. For each of these three assumptions, say whether it makes the gains of Figure 3.1 larger or smaller than the true gains, and why. Which assumption matters most for motorcycles?
3.7Data and code
| Data | Licence | Accessed |
|---|
Scripts: kich_ban/l3_loc_mang_duong.py (road network from OpenStreetMap) · kich_ban/l3_thoi_gian_di_lai.py (travel times, areas, comparison with VnExpress) · kich_ban/l3_tai_trang_nguon.mjs and kich_ban/l3_moc_ha_tang.mjs (opening dates) · kich_ban/l3_co_gioi.mjs (Table 3.1) · kich_ban/l3_cong_cong.mjs (Map 3.2, with the RAPTOR router of the atlas) · kich_ban/trich_dan.mjs (quotations). Each script stops without writing its output if a check fails.
3.8References
- Brueckner, J. K. (2011). Lectures on urban economics. MIT Press. Chapter 2, The monocentric city model.
- Liotta, C., Viguié, V., & Lepetit, Q. (2022). Testing the monocentric standard urban model in a global sample of cities. Regional Science and Urban Economics, 97, 103832. arXiv:2111.02112, CC BY 4.0.
- Nguyen, L. X., & Nguyen, T. M. (2017). Analysis of motorcycle ownership: A case study in Ho Chi Minh City. Proceedings of the Eastern Asia Society for Transportation Studies, 11. PDF.
- OpenStreetMap contributors (2026). Road network of Vietnam, extract of 16 September 2026. Geofabrik. download.geofabrik.de, ODbL 1.0.
- VnExpress (2026, 4 August). Xe buýt đến metro chậm hơn xe máy bao nhiêu lần? [How much slower than a motorcycle is the bus to the metro?]. vnexpress.net.
- Wheaton, W. C. (1974). A comparative static analysis of urban spatial structure. Journal of Economic Theory, 9(2), 223–237. doi:10.1016/0022-0531(74)90068-4
- World Bank (2011). Vietnam urbanization review: Technical assistance report. World Bank. Open Knowledge Repository, CC BY 3.0 IGO.
- Reports dating the links of Table 3.2 and the figures of Table 3.1: the government e-newspaper (Báo Điện tử Chính phủ); the Government Portal, Ho Chi Minh City section; the Dong Nai Provincial Portal; VOV; Thanh Niên; Tuổi Trẻ; Sài Gòn Giải Phóng; VnExpress; Pháp Luật TP.HCM. Each page, its date and its address are listed under Data and code.