Tuesday, January 28, 2014

Improved Public Transit in Mashhad, Iran

One of the nicest improvements I've noticed in Mashhad is the new bus stops. They all now look the same and include a metal-glass shelter, bench, and a big map of the route(s) (a schematic view of the stops and an actual city map). The bus loading area is marked with yellow zigzag stripes. The bus fare is paid electronically in the bus with a contactless smart card. No timetable or bus frequency information is yet shown in the stop though.




Thursday, January 16, 2014

Presenting NFD/MFD at Mashhad Traffic and Transportation Organization, Iran

Presenting some of our recent findings on network level traffic flow dynamics (NFD/MFD) at Mashhad Traffic and Transportation Organization, Iran. Thanks to Ehsan Jamshidi for organizing the seminar and the pictures. Also, thanks to Hani Mahmassani and Ali Zockaie for the research work and collaboration.



Monday, January 13, 2014

Network capacity, traffic instability, and adaptive driving: findings from simulated urban network experiments

Recently published in EURO Journal on Transportation and Logistics (January 2014)

Network capacity, traffic instability, and adaptive driving: findings from simulated urban network experiments
Meead Saberi, Hani S. Mahmassani, Ali Zockaie
This paper provides a discussion of network traffic flow stability and network capacity including existing definitions and measurement methods in the literature. To characterize network traffic flow, three phases are defined as free flow (F), inhomogenously congested (IC), and homogenously congested. It is shown that in large non-homogenous networks, the F → IC transition is usually a hysteretic phase transition. This paper examines the effects of adaptive driving on network capacity and traffic instability in a simulated network model of the Chicago metropolitan area as a large-scale highly congested complex network with exit flows. Results show that when the number of adaptive drivers increases, the general trend for network capacity is also increasing with some fluctuations due to randomness of traffic and overlapping effects of route choices. It is also found that adaptive driving may increase average network flow but may not necessarily improve network output, especially when the population of adaptive drivers is large and no gridlock exists. Results also suggest that with a larger population of adaptive drivers, hysteresis and gridlock are less likely to form. However, it is shown that bifurcation and multivaluedness can still occur even when the entire population of drivers is adaptive.

Monday, January 6, 2014

Mashhad Light Rail, Iran

A 2-car train arrives every 5 to 7 minutes. Real-time arrival information is displayed in every station. Fair is paid with a contactless smart card. The card can be used to pay for bus and BRT rides too. Stations have elevators and are fairly accessible for elderly and people with disability. I took the pictures during off-peak at Khayyam station which is not a very crowded station perhaps because of the land-use around it (mainly residential plus a private huge green space). The ridership seemed reasonably high during peak period and special events.