How to Mitigate Congestion with Queue Jumping

Congestion is completely removed from a metered road length, so get 90 percent of drivers to jump the entry queues with very low tolls. This causes slightly greater delay for ten percent of drivers left in the (free) queue, encourages mode change and shortens queues.

Metering traffic entering a road length to 90 percent capacity achieves ideal speed for all traffic, and two phase intersections get maximum use out of the road asset.

The public wants to see value, appreciates a choice, prefers paying for service rather than revenue raising and needs a simple explanation for reasonable actions. Express service must be offered to the vast majority, at a variable price, set low to attract 90 percent of vehicles, thereby providing service and also reducing queue size.

Toll price and queue delay need to be posted 24/7 including zero delay and zero toll. Having two options: express and queued, allows choice and the queued delay will usually be less than existing delay.

Traffic will vary and the priority will be to clear all express traffic each signal cycle with the variation most pronounced in the free queue. The system is stable because noticeable delays to the free queue will create mode shift.

Does queue jumping help to reduce traffic congestion

Buses already jump the queue. Variable tolls are widely used, for example on I-15 HOV (High Occupancy Vehicle) lanes, on normal commute days, the toll ranges between 0.50 and 4 US dollars, but can be raised to 8 US dollars in severe congestion. Most vehicles have electronic tags. With capacity increasing from metering and two phase intersections, queues will be smaller than now.

Congestion is a poor choice by local road authorities and they should consider taking a more positive role in traffic operation.

Do you think queue jumping will help mitigate congestion? If yes or no, tell us your reasons in the comment section.

Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.trong>

How to Eliminate Congestion with Metering

Metering limits flows to 90 percent of capacity, completely removing congestion for all modes, and presenting an attractive alternative to bus lanes. Bus lanes reduce capacity by upwards of 25 percent and in consequence, have prompted some bus lane removal and moderated installation of similar bus priority.

Ten percent spare capacity is targeted at the exit of each directional segment of a road, controlled (metered) by its entry signals, to ensure satisfactory operating conditions. Excess demand is cascaded upstream along trunk and branches until suitable places are found to queue excess vehicles and provide bypasses for priority vehicles with minimal impact on capacity.

In contrast, one lane for the exclusive use by buses, supported by bus phases, has a serious impact on road capacity and is used to force general traffic and freight onto other modes. Increasing congestion in itself is not sustainable and there are better ways to get community support for mode shift, without congestion, such as metering with queue jumping.

Does metering help to reduce traffic congestion

Metering formed part of the traffic management for the 2006 Commonwealth Games in Melbourne and was successful. Traffic signals have the capability of detecting spare capacity, controlling the traffic flows and communicating between sites in real time.

Queues already form at sites where demand exceeds supply and metering is proposed to have less restriction on supply than bus lanes. Buses will not be significantly restricted by mixing with other traffic. Community acceptance for bus priority is expected to be greater if the option of metering is proposed as it is less punitive than bus lanes.

Other complementary actions such as “restricted crossing U-turns” can speed up the bus by removing delays at minor intersections.

Local road authorities should consider converting existing bus lanes into metered segments and installing metering to benefit priority vehicles at all sites where there is congestion.

Do you think metering will help mitigate congestion? If yes or no, tell us your reasons in the comment section.

Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.

How to Mitigate Congestion with Two Phase Signals

Turns at intersections waste everybody’s time – better to process them on the approaches in parallel with cross traffic. Fifty percent more traffic capacity means shorter queues and less delay.

It has been known for forty years that no turns at intersections will allow more traffic through, not only because turn phases in series waste time, but because fewer phases mean less amber and red. When you wait for a turn arrow, your time is being wasted, get two phase intersections.

For the continuous flow option, re-position the front half of the turn lane on the target side of opposing traffic, connect it up like a plait and it fits within the existing footprint. Driving decisions are easier, but there are now five sets of signals, each with only two phases, one at the intersection and one on each approach.

For the P-turn option (for drive on left), turn left then U-turn or go through, U-turn and turn left (both shown). This saves a turn lane, but involves extra travel distance and passes the intersection twice so is only for minor movements.

Do two phase intersections really work

On Bangerter Highway in Utah, there are a number of sites with partial implementation on the major approaches, sufficient to demonstrate that capacity is increased, drivers accept the concept and the operation is safer than conventional intersections.

It has been evaluated for thirty three of the most congested intersections in Melbourne, Australia, including some multi-leg sites and the capacity increase is consistently around fifty percent. As with any new concept, there is continual learning and a number of options for further improvements including tandem or tridem approach cross-overs and pedestrian staging with refuges.

Every capacity increase at congested sites will immediately be filled by increased demand, but only as a response to reduced trip time. More trips made by car mean a higher living standard, but this must be limited and is for later articles on metering and queue jumping.

What about your local congestion

Local road authorities should consider converting a problem intersection into two phases using a continuous flow arrangement similar to those in Utah. For a typical signal phasing, sixty nine percent increase in throughput for both through and right turn should be possible.

There is no valid reason why road authorities cannot dramatically, economically and within the existing footprint, mitigate congestion at any site and it would be interesting to hear of any response. In this modern era with aerial photos, librecad, counts from traffic signals, and analysis tools such as Sidra it is possible for any professional to check the potential operation of any intersection, anywhere.

Do you think two phase intersections will help mitigate congestion? If yes or no, tell us your reasons in the comment section.

Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.