The programme of upgrading intersection traffic signals has been one of three main building blocks in New York’s modernization plan (Pic: Aftab Uzzaman)
The 5590 New York City Department of Transportation instituted the Midtown in Motion project to promote multimodal mobility in the Midtown Core of Manhattan, a 110 square block area or “zone” from Second to Sixth Avenue and 42nd to 57th Street. Control extended from 86th Street to 23rd Street, focused on the core zone.
MiM provides signal timing changes on two levels: Level 1 control starts from a pre-stored library of timing plans. These are designed offline and are relevant to arterials inside the Midtown study area. As a result of applying these specially designed timing plans, traffic progression patterns are adjusted, serving the overall purpose of regulating traffic into Midtown, thereby enhancing mobility inside the study area.
Level 1 control of the system alerts operators in the NYCDOT Traffic Management Centre (TMC) to changes in travel time and vehicle speed and recommends signal timing adjustments. The operator then reviews video cameras and other sources of information in the vicinity of the flagged avenue to identify the cause for the change in travel time. The TMC supervisor then decides the appropriate course of action to handle the event, which could be signal timing adjustments or requesting that NYPD address the situation.
To evaluate the system’s performance, a comparison of travel time by roadway segments was carried out. Based on the testing to date, in general the average speed improved noticeably. Speeds on approaches to the zone reduced to some degree as expected. Overall (inside and outside the zone) speeds improved, however.
Level 2 control is a split adjustment based on Severity Index (SI) which is related to an estimate of queue length (traffic congestion) by approach. The longer the queue is, the bigger the SI. The control algorithm attempts to reallocate green time between approaches to reduce queuing if possible and to achieve equity between the approaches. Under the current implementation, the splits are adjusted at every third signal cycle.
Level 2 can reduce queuing while achieving equity during the period, where feasible. This will vary by intersection. Level 2 implementation suggests that there are intervals wherein the ‘splits’ (time allocated for the green signal) can be adjusted to better service either the avenue or crosstown street, which is part of the objectives of MiM.
The extensive sensor network is enabling a rich data archive to be built. Combined with the record of actions taken and experience gained, this data will allow new traffic management plans to be developed.
The data now available due to the city’s ITS sensor network, suitably analysed and combined with operational experience, confirms a basic principle – that significant variation in the zone is the norm. While there are clear aggregate patterns, daily fluctuations require active traffic management that is designed to anticipate that reality.
MiM provides signal timing changes on two levels: Level 1 control starts from a pre-stored library of timing plans. These are designed offline and are relevant to arterials inside the Midtown study area. As a result of applying these specially designed timing plans, traffic progression patterns are adjusted, serving the overall purpose of regulating traffic into Midtown, thereby enhancing mobility inside the study area.
Level 1 control of the system alerts operators in the NYCDOT Traffic Management Centre (TMC) to changes in travel time and vehicle speed and recommends signal timing adjustments. The operator then reviews video cameras and other sources of information in the vicinity of the flagged avenue to identify the cause for the change in travel time. The TMC supervisor then decides the appropriate course of action to handle the event, which could be signal timing adjustments or requesting that NYPD address the situation.
To evaluate the system’s performance, a comparison of travel time by roadway segments was carried out. Based on the testing to date, in general the average speed improved noticeably. Speeds on approaches to the zone reduced to some degree as expected. Overall (inside and outside the zone) speeds improved, however.
Level 2 control is a split adjustment based on Severity Index (SI) which is related to an estimate of queue length (traffic congestion) by approach. The longer the queue is, the bigger the SI. The control algorithm attempts to reallocate green time between approaches to reduce queuing if possible and to achieve equity between the approaches. Under the current implementation, the splits are adjusted at every third signal cycle.
Level 2 can reduce queuing while achieving equity during the period, where feasible. This will vary by intersection. Level 2 implementation suggests that there are intervals wherein the ‘splits’ (time allocated for the green signal) can be adjusted to better service either the avenue or crosstown street, which is part of the objectives of MiM.
The extensive sensor network is enabling a rich data archive to be built. Combined with the record of actions taken and experience gained, this data will allow new traffic management plans to be developed.
The data now available due to the city’s ITS sensor network, suitably analysed and combined with operational experience, confirms a basic principle – that significant variation in the zone is the norm. While there are clear aggregate patterns, daily fluctuations require active traffic management that is designed to anticipate that reality.
- This is an edited extract from a paper presented by NYCDOT deputy director for systems engineering, Mohamad Talas, at the 19th ITS World Congress in Vienna, Austria, in October 2012. For a copy of the full paper, email <%$Linker:
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