Kiomars Nassiri-CEE 517 Presentation

Interconnected Signals at

Railroad Crossings

Kiomars Nassiri

CEE 517-Traffic Signal Systems

What is a Grade Crossing and Why it’s important?

Interconnected Signals at Railroad Crossings 2

Definition of Level Crossing (Grade Crossing) By FRA: A Grade Crossing is a location where a public highway, road, street, or

private roadway, including associated sidewalks, and pathways, crosses railroad tracks at grade (same level as the street)

They’re pretty much common here in the U.S. and elsewhere around the

world (Railroad cities, …) In the state of Illinois: 7720 Public level crossings

There were more than 118 000 level crossings in the 28 EU countries in

2012.

What is a Grade Crossing and Why it’s important? (Cont’d)


Grade Crossings per se are associated with hazards and risks due to the limitations in train’s braking system, it’s high momentum, etc.

An interesting piece of statistics:

“More people die in level crossing accidents each year in the United States than die in level crossing accidents in India.” Why? United States has more than six times India’s total number of level

crossings Hundreds of times its motorization levels

In the Europe: The number of fatalities in all railway accidents has seen a distinct,

downward trend for all categories of accidents, except for level-crossing accidents. This can be partly explained by the continuous increase in road traffic across

Europe, which increases the likelihood of a level-crossing accident.

A Potential Threat Nearby Highway Intersections


Thousands of these crossings that are in close vicinity of highway intersections (1000 ft. and Closer) Why this close proximity is considered as a potential threat to the safety of

grade crossing users?

There are 2 main issues (shown in figure below) Type 1 : Influence Zone (signal to tracks) queue Type 2 : Gate Spill Back (tracks to signal) queue

What are the solutions to this problem elsewhere in the world?

Major area of focus in this presentation

A Potential Threat Nearby Highway Intersections (Cont’d)


Some influential factors: 1. Types of vehicle using the intersection and level crossing 2. General speed of transition of vehicles through the level crossing and/or

intersection 3. Distance between the level crossing and the intersection 4. Drivers’ line of sight and resultant perception of rail and vehicle warning

systems, e.g. signs, lights, bells.

A Potential Threat Nearby Highway Intersections (Cont’d)


Potential reasons: 1. A red light; or 2. Congestion; or 3. A pedestrian movement (controlled or uncontrolled).

Type 1:

Type 2: Potential reasons: 1. Long vehicles passing the intersection from south going through; and 2. Right turning vehicles from East

Actions to alleviate problem type 2:

1. Ensure that vehicles (particularly long vehicles) will have sufficient time to clear the intersection and the level crossing before the level crossing starts operating.

2. Prevent vehicles from entering the roadway between the intersection and level crossing when the level crossing is operating.

What’s going on in AUSTRALIA?


Traditionally, rail and road signals at level crossings in NSW have been separate installations, even when they have been in close proximity

Generalized configurations when a level crossing and a signaled intersection are in close proximity

What about AUSTRALIA? (Cont’d)


Some other notes: The road authority will specify the Train Demand Response Time required.

The worst case time for the traffic signals to reach Clearance Phase and the minimum

duration of the Clearance Phase are determined by the road authority for each intersection.

The signal controller should incorporate two sets of phases; A normal set that the controller is permitted to run when there is no train demand A train demand phase set when there is a train demand.

What’s going on in AUSTRALIA? (Cont’d)


They mitigate this problem by interconnecting railway and highway signals. (How?)

Some Key Definitions:

Clearance Phase: The traffic signal phase used to clear motor vehicles that may be queued across the level crossing.

Clearance Phase Start Delay: The time required by the traffic signal controller to cycle to the Clearance Phase after the Train Demand is applied.

Queue Clearance Time: The time elapsed from the commencement of Clearance phase that it takes for a motor vehicle that may be queued across the level crossing to completely clear the level crossing



Operation of Interface In order that the traffic signals can synchronize with the level crossing, an

advanced indication of train approach needs to be provided to the road authority. This is called the Train Demand (TD).

Once the Train Demand is applied, the level crossing will commence to operate after the elapse of the Train Demand Response Time.

The Train Demand Response Time (TDRT) is the maximum advance warning time required by the traffic signal controller of an approaching train prior to the level crossing commencing to operate (XE).



Another Issue: Safety of intersection users (Peds and Vehicles) If the controller is to transition to a train demand phase set or clearance phase

when a train demand is received, the controller should be configured so that termination of the running phase is as early as possible provided that the following safety times are observed:

1. a minimum vehicle green of 5 seconds; 2. pedestrian clearance times as set; 3. yellow times as set; and 4. All red times as set.

All level crossings that are interfaced to traffic signals are to be provided with booms



Fault Monitoring and Management

If the controller detects a fault in either the train demand or crossing operating circuits, the controller shall operate as if a train demand had been received.

A traffic signal controller interfaced with level crossing signals should be connected to SCATS to ensure that the site is monitored and alarms notified.

In the event that the controller detects a fault with the train demand, crossing operating or traffic light response signals a high priority alarm (e.g. SF alarm) should be generated and communicated through SCATS. SCATS should be configured to recognize these alarms and log relevant information.

Back to North America CANADA


In terms of Rules: The operation of traffic signals on a road approach shall be preempted by a grade

crossing warning system:

a) Where there is less than 60 m between the stop line for the traffic signals and the rail nearest the road intersection; or

b) If it has been determined that traffic queued for the traffic signals regularly encroaches closer than 2.4 m to the rail nearest the road intersection.

ROAD/RAILWAY GRADE CROSSINGS TECHNICAL STANDARDS and INSPECTION, TESTING

and MAINTENANCE REQUIREMENTS



A Study in Region of York:

Engineers placed a video trailer at the six signalized intersections to record footage of traffic queued at the intersection during peak traffic periods.

Analyzed queues and Gathered information on: The queue lengths at the end of

each signal cycle Time required for a vehicle at the

end of a queue to proceed forward Potential unsafe driver behavior

associated with the activation of the active warning system

Analysis done using Synchro 7



Problems and Solutions: 1. Changes to Access Management:

• Problem: Some accesses located just upstream of tracks were causing traffic obstructions at a railway crossing

• Solution: Turn or time based restrictions to accesses 2. Changes in Signal Timing

• Problem 1: At locations where the LOS on the cross street approach was considered adequate, they examined the reallocation of green time to the railway crossing approach

• Solution: Adding to the green time on the affected approach resulted in a modest decrease in the 95th percentile queue length in Synchro

• Problem 2: At one intersection, traffic in the left turn lane was observed queuing back to the tracks while at the same time there were only a few vehicles queued in the adjacent through lane

• Solution: When the length of the protected left turn phase was doubled, the 95th percentile queue length decreased significantly in Synchro.



Problems and Solutions: 3. Adding Turn Lanes:

• Problem: At two of the signalized intersections, both the turning movement counts and the video footage indicated a heavy right-turn movement, although a separate right turn lane was not provided.

• Solution: When modeling operations at these intersections with the addition of a right turn lane, there was a substantial decrease in the 95th percentile queue length

4. Queue Detection 5. Changes to Operations at Downstream Intersections 6. Installing Pre-signals: Prevent queues forming across the level crossing

(provide a controlling traffic signal on the approach to the level crossing).



7. Signal Pre-emption TxtDOT worksheet was used to determine if additional time is required for the traffic signal to move stationary vehicles out of the railway crossing before the arrival of a train

For one intersection, 22 seconds of additional warning time would be

required, which is considered feasible.

In the remaining intersections, 34 – 60 seconds of additional warning time would be required, which is considered to be infeasible at these locations due to:

What about NEW ZEALANDERS?


New Zealanders’ term for intersections in close proximity of railroad level crossings: Short Stacking

Where there is short stacking, consideration should be given to providing: 1. Auxiliary road space (slip lanes or shoulder widening) to allow a vehicle

to escape or wait clear of the railway line or road traffic.

2. Where an alternative route exists, partial closure (to vehicles over a defined length) or complete closure

3. Channelization, realignment or relocation of the road

4. Realignment of the railway line

5. Active control of the level crossing and intersection

What about NEW ZEALANDERS?


Emergency-escape zones on the departure side

These bays should be designed in such a way that they will only be used for the purpose intended. This generally means that exiting from the bay does not mean the driver can simply drive forward but is required to filter back into the queue of vehicles in the adjacent lane. To achieve this, the design would normally provide for no more than two cars or a single unit truck and have a physical island with non-mountable curbing terminating the bay.

Unresolved issues


Issue: This is pretty much common around the world to have flashing-light signals operate for at least 20 sec before the arrival of any train.

× While 20 sec might be adequate for railroad tracks that are within 200 ft. of signalized

roadway intersections, it is usually grossly inadequate for separations approaching 500’. Issue: Almost none of the codes offer any methodology for increasing this time. They only declare that an engineering study is needed.

Increasing the time of operation of flashing-light signals at railroad crossings may not be an acceptable method of providing longer times. Why?

× Motorist delays may become excessive tempting motorists to consider risky

behaviors. Instead, different types and arrangements of train detection devices may be required

Unresolved issues


Most of the time, hopefully, the first stage of preemption will be wasted because no roadway vehicle will be stopped foolishly in the pathway of a train.

Motorists who crossed the track may enjoy reduced delay from the traffic signal due to preemption by being allowed to proceed immediately.

This can be self-defeating if it induces motorists to try to avoid delay by

deliberately and recklessly crossing a track even though they are aware that sufficient storage space is unavailable!!

Recommendations & Conclusion


Many of the solutions identified, such as access management and making adjustment to signal timing can be implemented in a short time frame and are viable alternatives to signal pre-emption.

Other treatments, such as adjustments to lane configuration and queue detection, while higher in cost, still offer a solution that are viable alternatives to signal pre-emption

Signal pre-emption needs to be considered in the context of: • Distance between the signals and the railway tracks • The greater uncertainty that the queue would be completely cleared prior to the

arrival of the train; and • The distance upstream (on the railway tracks) that the advance warning would

need to be placed to activate pre-emption at the traffic signals.

Recommendations & Conclusion


Preemption circuitry usually can be installed only where a roadway intersection has a traffic signal and a nearby railroad crossing has active Warning devices.

Preemption can increase the risks to pedestrians and roadway traffic who are not expecting their green phases to be abruptly truncated with no apparent cause at the time.

Preemption settings involve a trade-off between the risk of deaths and injuries to motorists stopped stupidly and trapped in the pathway of an oncoming train and the delays imposed on all other motorists who are always in a hurry and intolerant of incurring much delay for the benefit of stupid motorists who (fortunately) are rarely present.


References

1. Australia. Roads and Traffic Authority (RTA). New South Wales. Traffic Signal Design (Appendix F-Level Crossing Interface Concept of Operation). 1st ed. N.p.: Roads and Traffic Authority, 2010.

2. Suggett, Jeff, and Paul Nause. Analysing and Mitigating Queues at Signalized Intersections Adjacent to Railway Crossings. Rep. N.p.: Associated Engineering, 2013.

3. New Zealand. NZ Transport Agency. Traffic Control Devices Manual (Part 9 Level Crossings). 2nd ed. N.p.: NZ Transport Agency, 2012.

4. ECONOMIC AND SOCIAL COMMISSION FOR ASIA AND THE PACIFIC. Evaluation of Cost-effective Systems for Railway Level-crossing Protection. New York: United Nations, 2000.

5. Timing Issues for Traffic Signals Interconnected with Highway- Railroad Grade Crossings. Rep. no. RC-1578. Lansing: Michigan Department of Transportation, 2013.

6. RAILWAY SAFETY PERFORMANCE IN THE EUROPEAN UNION. Rep. no. 4. 4th ed. N.p.: European Railway Agency, 2014.

7. Level Crossing – Traffic Signal Design Interface Agreement. Tech. 2nd ed. Sydney: RailCorp – Roads & Traffic Authority, 2010.

8. Level Crossing Design. Rep. no. ESD-03-01. N.p.: Australian Rail Track Corporation, 2012. Print. Engineering (Signaling)


Thank You

Kiomars Nassiri-CEE 517 Presentation

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