Oaklane Caution Light

Yellow light in action

The Problem

The flagger controls the cars on a Quarter Midget racetrack using a series of flags. For the most part this works well. One of the problems is when a driver has passed the flagger, and won't see the yellow flag until after the accident. If the driver has just passed the flag-stand when the flagger throws the yellow flag, the driver is sure to go past the accident before he/she sees the flagger. Most if not all, professional race tracks solve the problem with a series of flashing yellow lights around the track to warn drivers when the flagger is not in the driver's sightline. This reduces the chance of a driver arriving at the accident at racing speed :-( QMA flagging guidelines permit a yellow light in turn three, which is controlled by the flagger. To increase the safety at the track the Oaklane Quarter Midget Racing Club decided to onstall a yellow caution light at their track. This page describes the selection, installation and use considerations.


The light needs to be: weatherproof, directed towards the drivers and easy to see in all lighting conditions. Three types of lights were considered: comercial strobes, emergency vehicle lights and traffic lights.

There is a local dirt track that uses a bunch of yellow strobes around the track. From the stands, they seem a little weak. Perhaps from the driver's viewpoint, the Fresnel lens works better. The cylindrical lens promotes reflection of sunlight, which would reduce the on/off contrast. Weatherproof strobes are quite expensive. A strobe light would need to have a housing to cover it to keep the weather and sunlight out. In addition, replacement strobe tubes are not easy to come by at the local hardware store.

Emergency lights from a wrecker could be made to work. They are easy to see and -- naturally -- flashing. They are weatherproof, but would still need to have a cover to keep the sun out and improve contrast in bright conditions.

A standard traffic light fills the all above requirements and is used by many quarter midget tracks around the country. They are quite large, over 100 square inches of illuminated area per element and specifically designed to signal vehicle drivers under all lighting conditions. The housings are weatherproof and designed on mount directly to light poles. A flasher can be added to make the light eye-catching when activated. The biggest advantage is the optical design of the light, as it provides a high degree of contrast between "on" and "off" in all conditions. The traffic light directs all the light toward the drivers so it won't be a distraction to others around the track. The sunshades insure the lights will have high contrast even in the direct sun that hits turn 3 at Oaklane every afternoon.

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2 unit traffic light
Two unit traffic light
mounted on pole
The light is made up of two standard 12-inch elements with yellow lenses purchased from Twin Green Traffic Signals. The folks there were very helpful in making sure we got the right thing. One special feature was the lower arm electrical entry, allowing us to run the wire outside the pole. This feature is normally used for wooden poles, even though we were mounting on a metal pole.

anatomy of a traffic light
Anatomy of a traffic light
The key to the high visibility of a traffic light is its efficient optical design. Light from a clear bulb is collected by a large reflector and pushed out through the yellow lens. A regular light bulb will work, but there are special traffic light bulbs. They are clear, have a heavy-duty filament and a small internal reflector to help push the light out the front, where it belongs. The large shade is important. It keeps the light visible when the sun is shining onto the front of the signal.

Solid State Flasher
Solid State Flasher
A bright, high contrast light is one component of an effective light. The other important item is the flasher alternating the two lights. A solid state flasher, mounted inside the light, from Lights to Go! flashes the two lights flash back and forth. The flashing is important in getting the drivers attention. A proper flash-rate is important. The drivers are looking in the direction of the light for a short time. If the flash-rate is too high, the lights will appear to be half-on and half-off. The solid state flasher is adjustable to get the most effective rate. In addition, the flasher is designed to continue to flash even when one bulb is burned out.

The Switch

Switch Box
Flagger's Switch Box
Even the brightest light won't do any good if the flagger can't turn it on. The switch needs to be easy to operate with the flagger's hands full. Two switches are provided so the flagger can use the method they prefer. One switch is a sealed push-pull emergency switch with a large red button. The other switch is a heavy-duty foot switch. The foot switch attaches via a short cord so it can be positioned to the flagger's preference. It can also be removed at the end of the night to be stored indoors. Both switches are maintained-contact type, so the light stays on until turned off.


Installed Light
Installed Light
Conduit Entry
Conduit Entry
The light is mounted on the light pole in between turns 3 and 4 using standard mounting arms. These are typically fixed with stainless bands. We used large hose clamps from the hardware store instead. They worked quite well. The light is rotated on the pole a bit to prevent the shades from protruding beyond the wall. This also keeps the light in "turn three" per QMA guidelines.

Switch Box
Flagger's Switch Box
The hand/knee switch is a sealed industrial emergency switch mounted in a weatherproof steel box. The wires are shown coming through a shallow cut in the pavement. The cut was sealed with hydraulic cement. The foot switch connects via a weatherproof outlet. This allows switch removal at the end of the night and out of the weather storage.

Installing Conduit
Installing Conduit
Conduit Entry
Burying Wire
Light power is supplied from the scoring tower. It travels around one side of the track via UF cable buried in a ditch. It then runs in a shallow pavement cut, to a short conduit, to the weatherproof box. The switched circuit runs in conduit along the outside of the track wall. Waterproof compression fittings join the conduit together. The conduit is fastened next to the ground so that it won't get damaged when a person stands on it. Drilling a 17/64-inch hole in each I-beam was a pain, but the installation should provide years of trouble-free service.

So, how does it work?

Driver's View of Light
The Driver's View
Drivers have no problem seeing the light from the back straight even with the tiny 60W bulbs. The light stands out even in full sun. A pair of 90W bulbs is planned for future installation to make the light even brighter. While the light works well, it will take some time for the flaggers to become used to working with the light. It is a major change to their routine. All of the flaggers interviewed prior to this project that had a light at their track liked them. We think it will be the same at Oaklane. Check back later in the season and find out...

light from driver's view
Here is a video of the light in action from the driver's view taken while sitting on the back straight looking into turn 3. Mission accomplished.



For the first few races of the season the flaggers tried to use the light. Turning it on was not a problem and the drivers saw the light from the back straight as designed. There were two big problems: the flagger would occaisonally bump the switch, turning on the caution light during a race. The flagger would often forget to turn the light off before a restart. Both of these problems caused confusion on the racetrack. These problems caused the club to decide to discontinue using the light during racing.


Club members discussed the problem at length, both on race night and on the e-mail list. Several members came up with the idea of using a timer to turn the light off. In addition, the maintained contact switch on the front of the box was replaced with a momentary contact switch on the top to prevent accidential activation. Since the drivers were reacting well to the light on the track it was decided to try changing the switch gear to prevent the light from being on at the wrong time.

New Switch
Improved Flagger's Switch Box
The hole for the original switch was covered over with a stainless plate and the new switch mounted on the top of the box. The new switch is a normally open momentary contact type with a mushroom style button. It is a common item at an insustrial supply house.

NEMA 4X actuator with red Button (MSC Part Number 54100706)

Contact Block
Normally Open contact block for actuator (MSC Part Number 54104914)

The new switch gear has been used for one race night and there were no problems. The light was never accidentally deployed and was never on when the green flag fell. So far, so good.

Timer being placed in switch box.
The timer just fits into the weatherproof box. It is set to 15 seconds which equals 2-3 laps depending on the class. During racing this worked well as the light is on long enough for all the drivers to see and still turns off long before the cars are ready for a restart.

Delay off, 0.6-60 sec timer (MSC Part Number 54023486)

11 pin octal socket for timer (MSC Part Number 54038666)


It was a huge job to run all the wire to complete the installation. Thanks to Chris, Nick, Dave, Jim, Larry, Mark and Tom for all the hard work to get the light installed during work day. Thanks to Brian for helping with the research phase of this project including taking pictures of the Bayands and Tri-Valley tracks.

Parts Sources:

New traffic lights and solid state flasher from Lights to Go!
Used traffic lights in all configurations Twin Green Traffic Signals.
Weatherproof electrical box and other electrical components MSC Industrial Supply.

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