After initially purchasing an HO scale slot car racing set most racers quickly tire of the small circuits these sets provide, and start thinking about building a more challenging raceway. Several crucial design decisions need to be made early on in this process. The decisions you make will effect the ultimate success of your design, so weigh your options carefully.

The first decision you will need to make is the overall size of your HO slot car track table. While a challenging racing circuit can easily be built on a table as small as 36' × 80' most racers build a larger layout. Common sizes are 4×8 or 5×9 foot tables. These will normally provide enough room for a variety of turn radius sizes and several fast straights. Tables of this size can be constructed from standard-sized sheets of plywood.
If you have enough room for a larger layout then you may want to consider a 5×12 or 6×16 foot table. Keep in mind that whatever table size you ultimately select you will need at least an additional two feet on each side to move around when you have to re-slot your cars.
Tables that are wider than 6 feet will make it difficult to re-slot cars at the center, while tables longer than 16 feet make it very difficult to see the cars at the far end.
Unless your space is very limited you should try to build the largest table possible. Then, even if you do not initially fill it with track you will be able to expand your layout later on. A table of at least 5×9 feet would be an ideal starting point. A 5×9 foot table allows for much more track than a 4x8 foot table. The additional width of a 5×9 foot table makes it much easier to fill the center with an extra set of turns and straights. The extra foot of length also makes for longer and faster main straights.
See the Tables section of this web site for construction ideas on building any of the table sizes mentioned above. If your space is very limited you may also want to look a the Tuckaway section which describes a challenging race track that can be built on a small 36' × 80' table.
Whatever table size you ultimately decide on, keep in mind that you will have to live with your selection and its size restrictions for many years to come. Building a solid table requires time and effort so choose wisely.

Once you have decided upon the size of the table that you wish to build you will need to consider how many lanes your race track will have. Most home racers build race tracks with either 2 or 4 lanes.
Seriously consider building a 4-lane race track instead of a 2-lane circuit. The benefits of a 4-lane raceway are numerous. The outside edges of turns require guard rails or borders to prevent the outside lane's car from dropping off the edge of the track. The outside lane has an unfair advantage because the driver can simply 'lean' on the guard rail instead of driving through the turn. On a typical 4-lane race track three of the four lanes will not have this advantage.
When you have only two racers a 4-lane layout assures that the center two lanes will provide for fair and equal racing because neither racer has the advantage of being able to lean on the guard rails.
You may think that only two lanes will ever be used, but be assured that when guests see your race track they will want to try it, and over the holidays it's not unusual for all four lanes to see action.
If you are planning on building a race track with realistic landscaping a fair and equal 2-lane configuration is possible. Landscaped layouts normally include curbs or borders on the outside of most turns. These borders will allow the driver in the outside lane to hang the rear wheels off the racing line without falling off the track.

The diagram above illustrates a border added to the outside of a turn to allow the slot car in the outer-most lane to drive through a turn without falling off the track or gaining an unfair advantage by leaning on a guard rail.
Turn borders can easily be made by cutting and placing Foam-Core display board or Masonite hardboard around the outside of all turns. When painted red and white these borders can be very attractive and lend to the overall realism of a landscaped track. See the Borders section of this web site for detailed instructions to make your own track borders.

After choosing the table size and lane width of your race track you will want to consider the actual layout configuration. HO slot car tracks fall into two main categories; flat raceways and race tracks that employ an overpass, or over-and-under configuration, similar to the classic figure '8'.
A flat style raceway is much easier to build. Track sections simply need to be fastened to the table to complete the construction phase. Track designs that employ an overpass will require additional bracing to support the elevated sections of track. Layouts using an overpass can be designed to have a more equal lap length and will add more variety and interest to your race track.
If you are planning on building a landscaped race track by all means consider a track design that uses an overpass. The elevation changes required to accommodate the overpass will add realism to your track and make it more visually appealing. The grades leading up to and away from the overpass will present many interesting landscaping opportunities.
Winston Cup NASCAR fans may want to build a replica of their favorite stock car oval, but keep in mind that this simple type of track configuration offers very little in the way of variety. Oval and tri-oval superspeedways quickly become very boring in HO scale. Better to investigate a standard road course, with its wider variety of corner styles and straight lengths. In recent years NASCAR has sanctioned race events at road courses such as Watkins Glen in Upstate New York. The NASCAR fan can create an interesting and challenging road course and still run stock cars.
The Layouts section of this web site illustrates several race tracks using both a flat style approach and the overpass configuration.

One more thing that you will want to consider early on in the design phase is whether or not you will be building a landscaped layout. A landscaped layout adds a certain realism to your racing. Landscaped layouts will normally require more green space between the different sections of your track though, so if you plan to landscape your layout in the future leave a little extra room between track sections to accommodate your landscaping and track-side buildings.
A happy medium between a fully landscaped race track and a bare board can be achieved though by covering the entire table top with a dark green indoor/outdoor carpet before mounting your track. Carpet glued to the table top will provide a much quieter running track and eliminate the toy-like click-clack sound that plastic track sections generate when mounted directly to a wooded table top. A dark hunter green colored carpet also closely resembles grass and foliage.
A minimalist approach to landscaping can also be quite attractive. A dark green carpet with only the minimum of foliage and track buildings can create a very appealing racing circuit. Try an approach similar to an Architect's model, where the track is the main attraction and the landscaping is only added to accentuate the racing circuit. A few pieces of model railroading lichen glued directly to the carpet to create colorful shrubbery and a few buildings will give your layout some height and color. The orange colored guard rails when combined with dark green carpet add a nice contrasting color scheme.
If you plan to build a fully landscaped race course then investigate the wide range of landscaping products available to HO model railroading enthusiasts. HO scale train scenery is ideal for recreating authentic and realistic race track settings. A fully landscaped race track can become a hobby in itself. Many racers take years to complete accurate representations of their favorite tracks. Watkins Glen in the fall is a favorite theme for many Formula 1 and sportscar fans.

The secret to a successfully designed HO scale race track is course variety. A variety of different types of corners, several long, fast straights, mixed with a few connecting chutes to join them all together will provide an interesting and challenging race track that will test both a driver's skill and ability to prepare a well handling HO slot car.
Try to include several different turn radius sizes in your race track design as well. A track comprised solely of 9' radius turns will become rather monotonous after only a short period of time. Instead, try to use the full range of turn sizes available; from the ultra-tight and slow 6' radius turns all the way up to the fast, sweeping 18' radius corners. See the Track section of this web site for a list of track section sizes available from the various track manufacturers.
A variety of turn radius sizes will make for a much more challenging race track. Different turn radius sizes will also provide you with an opportunity to fine-tune your slot car setup skills, not to mention your driving ability.
The selection below describes some of the most common corner types found both in the real world of road racing and also on well designed HO scale race tracks. Try to design your race track to include several of the different turn styles that are illustrated below.

The first corner style listed here is the Hairpin turn. Almost every road racing course and sportscar track has at least one of these. A hairpin turn is often found at the end of a long straight, forcing a driver to slow drastically after a long high speed run.
This corner's name comes from the shape of the turn itself. The most famous hairpin turns are found at the end of the Mulsanne Straight at Le Mans, Le Source at Spa-Francorchamps and the Station Hairpin at Monaco.

In the illustration above the cars would enter on the left side and turn left for 225 degrees, then exit through the final 45 degree right hand turn.
An HO scale hairpin turn can be created using 6' and 9' radius turns. From a track design standpoint the hairpin turn provides a simple means of folding the circuit back upon itself while using very little of the table's width.
A second type of Hairpin turn featuring a decreasing radius entry and expanding radius exit is shown below.

Using a set of 9' and 12' radius 1/8 circle turns followed by 6' and 9' radius curves at the apex and then another set of 9' and 12' radius turns at the exit is all that's required to create this type of Hairpin turn.
This turn configuration, while challenging, is much easier for younger racers and novices to negotiate.

The next corner type is the Parabolic turn. Parabolic turns come in two varieties; increasing radius and decreasing radius corners. In the illustration below, if the cars were to enter from the left side each turn section they encounter would have an increasing or wider radius. On the other hand, if the cars were to enter from the right side each turn section decreases or tightens.

An increasing radius parabolic turn requires a low entry speed and a progressively faster exiting velocity. The decreasing radius parabolic turn has exactly the opposite consequences, here the car can enter at a higher rate of speed, but must progressively slow as it goes deeper into the turn. Exit speeds from a decreasing radius parabolic turn are much lower than they would be for an increasing radius corner.
Use an increasing radius parabolic turn when the exit of the turn leads onto a fast straight. A decreasing radius parabolic turn is best used when the section following it is a slow speed section of the course.
Parabolic turns offer some of the most challenging corner configurations possible. Most track designers try to incorporate both an increasing and a decreasing radius turn somewhere in the circuit to challenge the driver and set the car up for the track section to follow.
Parabolic turns can be created using 45 degree (1/8 circle) track sections arranged so as to always use the next smaller or larger turn radius. The illustration above uses, from left to right, a 9', 12' and 15' radius turn section for the inner lanes and a 12', 15' and 18' radius turn section for the outer lanes.

The next type of turn is the Carousel. This type of corner is usually a constant radius turn comprised of the largest turn radius sizes available. The 4-lane example below uses 15' and 18' radius turns for all sections of the corner. In the illustration below cars would enter from the left side and exit at the right.

Carousel turns provide an excellent means of connecting two long straights without losing too much speed in the turn itself. From a track design standpoint, the carousel turn, much like a hairpin, provides an excellent opportunity to fold the track back on itself without using too much of a table's width.

The Sweeping turn, or sweeper as it's often called, is a nice alternative to the standard 90 degree curve. By placing a short straight section between two 45 degree turn sections you can create a turn that is much more interesting and challenging to drive than a standard 90 degree left or right hander.
The overall effect of using a sweeping turn is to create two individual and distinct turns out of a the single 90 degree corner. For added variety you can use different turn radius sizes for the entry and exit as well.

The diagram above illustrates a 4-lane sweeping turn employing differing turn radius sizes for both the entry and the exit. If cars were to enter this turn on the left they would first negotiate a 12' or 15' radius turn section followed by a short straight section. Exiting to the right they would finally negotiate a 15' or 18' radius corner.
The dynamics of a changing radius sweeper are the same as those for the Parabolic turn described earlier. If the exit leads onto a fast portion of the track put the larger radius turns at the exit. Conversely, if the exit leads to a slow section of the course place the smaller radius turns at the exit instead.

The Kink is a gentle bend placed somewhere in the middle of a long straight. A kink forces a driver to lift slightly and then get right back on the power. This type of turn, while deceptively simple can test a driver's skill. Eau Rouge at Spa-Francorchamps is a classic example of a fast kink.

Kinks are normally found towards the middle of long, fast straights. Try to make the overall turn radius as gentle as possible so that cars can maintain a high rate of speed both on entry and exit. The idea here is to make the driver lift slightly and then get right back on the throttle. No braking is done for this type of turn, other than the slight slowing of the motor. Use 15' and 18' radius turn sections whenever possible to form kinks.

The 180° Turn is normally a constant radius curve that joins two fast straights. Cars brake well before the entry and then accelerate through the turn to the exit, but unlike the hairpin turn described earlier, this turn employs larger radius curve sections to allow cars to negotiate it at a much higher rate of speed. 15' and 18' radius turn sections are recommended for this type of corner.

From the track design standpoint the 180° turn allows the track designer to fold the racing circuit back upon itself. A short straight section can be added in the middle to create a pair of distinct turns, each with a separate braking zone and exit apex.

A Chicane is normally inserted into a fast straight to slow cars down. Chicane sections have become popular in recent years on real-world race tracks as a safety device to slow ever-faster race car designs.
Unlike the kink described above, a chicane has a distinct braking zone prior to the entry apex, followed by a steady throttle section leading up to the exit apex. A driver can not get back on the throttle until the exit apex is reached, making the chicane a challenging turn on any HO scale race track.

The entry and exit speeds for a chicane can be manipulated by the careful choice of the turn radius sizes you select. In the illustration above both the entry and exit sections are the same radius, but this could just as easily be adjusted to create a slower entry and faster exit with decreasing and increasing radius sections respectively.
A short 3' or 6' straight section of can also be added at the center of the chicane. This would prolong the steady throttle section of the turn, making it even more challenging to drive.

Classic Esses can be found on almost all of the worlds best known race tracks and road courses. This turn's name comes from its 'S' shape. Esses, like the chicane mentioned above require heavy braking prior to the entry. Esses work to slow a car down much more though than a simple chicane.
Esses, while often thought of as a single course element, are really two distinct turns placed end-to-end.

The diagram above illustrates classic esses with a constant radius entry and exit, but like the chicane, the entry and exit sections can be of different radius sizes to better facilitate a transition to whatever type of track section they proceed.

The Washboard turn is found on many commercial HO slot car tracks. Racers either love or hate this type of turn. While offering no real-world context they can be found in many HO slot car track designs. Purists normally avoid this type of turn configuration. Esses or Chicanes are usually a better choice, but it is included here because some racers find it interesting.

If you decide to incorporate a washboard turn in your track design don't overdue it, a pair of left-right transitions will be sufficient. This type of turn configuration can become very tedious to negotiate, and because the entry and exit sections do not line up, it will be difficult to remove and replace with straight track sections later if you change your mind.

The next corner style listed here is actually a series of turns combined to create a distinct course element. Its name comes from the Bus Stop turn at Belgium's Spa-Francorchamps.

In the illustration above, cars enter the esses from the top and exit towards the bottom through the chicane section. The Spa-Francorchamps circuit was originally created using public roadways that cut through the Ardennes Forest. The Bus Stop section was just that, a bus stop on non-racedays. WW II History buffs will recall that this is were the 'Battle of the Bulge' was fought.

The last corner style listed here is a Banked Turn. Banked turns allow a car to travel much faster than they normally would through a flat turn. Banked turns work best when placed before a long straight. This arrangement allows the cars to exit the banked section at a higher rate of speed, and consequently travel down a long straight faster than they would if they exited a flat turn.

The picture above illustrates the proper placement of a banked turn section to create a faster straight following the banking. Placing a banked turn at the end of a long straight does little to improve the speed of a car unless another long straight follows it as well.
Tomy AFX banked turn sets are available in 9' and 12' radius sizes. They can be combined to form a 4-lane high-bank turn. Short straight sections can also be inserted between banked turn sections to create interesting NASCAR-style super speedway turns.
Note: If you plan on running older vintage Aurora ThunderJets you'll need to increase the length of the straight leading up to the bank so that these older, slower cars can get up a good head of steam to make it through the banking.
You'll probably need three or four full 15' straights before the banked section. If older T-Jets aren't traveling fast enough when they enter the banking they may not be able to make it around the banked section without sliding down to the bottom of the turn.

The race track below illustrates several types of turns combined to make a challenging racing circuit. This layout fits on a single 5×9 foot table and provides a lap length of just over 50 feet per lane. This layout uses 12' and 15' radius turns whenever possible.
Driver's stations are placed along the left edge of the table, where they can easily view the entire circuit. Turn marshals stand around the other three side of the table so as not to block the drivers view.

Cars travel down the main straight on the left side of the drawing and enter a decreasing radius 90° left hand turn.
Upon exit a short chute leads to a tight left hand turn feeding into a 180° hairpin. Exiting the hairpin, cars are then required to negotiate an increasing radius sweeping turn punctuated with short connecting straights leading on to a long infield straight.
The infield straight leads into a 90° right hand turn, short straight and then another 180° medium radius turn. A pair of right/left hairpins feed out onto a short straight running up to a wide radius carousel and then out onto the back straight.

Here's an inventory of the Tomy AFX track sections required to build this layout:

Straights

(32) Tomy AFX 15' Straights

(16) Tomy AFX 9' Straights

(16) Tomy AFX 6' Straights

(2) Tomy AFX 3' Straights

Turns

(6) Tomy AFX 15' 1/8 Circle Turns

(20) Tomy AFX 12' 1/8 Circle Turns

(28) Tomy AFX 9' 1/8 Circle Turns

(14) Tomy AFX 6' 1/8 Circle Turns

See the Borders section of this web site for detailed instructions on fabricating your own track FIA borders.

Several track design methods are available. The easiest way to design a track though is to use slot car track design software. Design software allows you to try numerous configurations until you have a track you really like.
If you have a large inventory of HO scale slot car track sections on hand you can physically lay out your proposed track design ideas on your table and try them out. However, this will only work if you have all of the possible track section types on hand and in sufficient quantities to complete your designs.
If you have some HO track sections available you can lay these out, and mark their location on the table top. Then pick them up and use them on another section until you have the entire track laid out.
Another alternative is to use graph paper and a compass to sketch out your various design ideas on paper. You can also make full-sized cardboard track sections and use these to physically lay out your proposed designs. See the Track section of this web site for track dimensions to use when making your templates.
Whatever method you decide to use, once you have a track design you like and track sections on hand to recreate it, test it before you mount it permanently to your table. Driving the actual race course you have just designed will allow you to verify that the circuit is challenging and the very best that you can come up with. What looks good on paper may not be nearly as challenging to actually drive. It's important to test drive your proposed layout for several days before committing to it.