| The use of local materials for rural cycle tracks | | | | Some cycle way areas may have their own deposits |
| Where ever possible it is best to use materials which | | | | of gravel or other suitable material which can be dug |
| are obtained on site or near to the route of the | | | | and used for path construction. In some areas old |
| track. They have the advantage of being 'natural' to | | | | quarry workings or spoil from various industrial |
| the site, and of a colour and texture which should | | | | developments may provide material. |
| blend well with the local landscape. | | | | Old railways or pre-existing paths |
| They are also free. However, these advantages | | | | Where the track is to following old railway routes or |
| need to be balanced against the time taken to | | | | an existing path or track it is almost certain that the |
| gather or dig the material, and any weakness in the | | | | available site materials will be sufficient in themselves |
| available materials. The stability and usability of these | | | | with just added SMR to stabilise and bind producing a |
| on site materials can be improved dramatically by | | | | strong long lasting fit for purpose cycleway, although |
| mixing in a small amount of SMR soil stabilisation | | | | in some cases especially where the occasional vehicle |
| binder. Providing that the methodology of blending | | | | access is required a thin rolled wearing course with a |
| mixing, laying and final compaction stages are carried | | | | surfacing layer 50mm thick of 'fines', 'dust', 'blindings' |
| out correctly. | | | | or other material sized about 6mm down to dust |
| Streams | | | | would be beneficial. |
| Material from streams is often suitable as an | | | | Another material for use as a wearing course where |
| aggregate base mix providing the stones are still | | | | it is available is the waste material from the quarry |
| angular and have not yet been rounded by the action | | | | bottom this is the cheapest type of quarried stone. |
| of water. It would be best to use material from the | | | | It is obviously very variable, but should contain a lot |
| edge of the water or from shallow pools. Any fine | | | | of fine sediment and will bind easily to the SMR |
| sediment in the streams will also be useful for mixing | | | | treated surface if passed over with a vibrating roller |
| in as fines with the angular stone. Old buckets with | | | | or plate. |
| holes are useful for this job as they will quickly | | | | A total depth of 200mm for base and any surfacing |
| separate out any water. Always beware of taking so | | | | should be sufficient for cycle tracks, and this would |
| much from one place that the course of the stream | | | | normally be laid directly onto the soil or subgrade. |
| is altered. | | | | Tracks need sensitive treatment in their construction |
| Outwash deposits | | | | and repair if they are to blend into a rural or wild |
| Outwash deposits are a good source of path making | | | | landscape. They should be laid with variation and |
| material, and are usually conveniently graded during | | | | irregularity avoiding hard edges where possible, drains |
| deposition. | | | | and other features. |
| Scree | | | | The hydrogel polymers in the SMR will quickly bind |
| Scree material is usually very angular, and is excellent | | | | the recycled path material to the soils edging the |
| granular stock for the path base mix. | | | | path and it should be possible to avoid path edging or |
| Borrow pits | | | | revetments. Any edging that has to be used to |
| A traditional method of gaining material for path/track | | | | contain the path material will show up as a hard line, |
| construction was to dig 'borrow pits'. These were | | | | noticeable even after vegetation partly covers it. |
| small pits or quarries dug at intervals along the route | | | | These edgings, (e.g. railway sleepers), are only |
| of a track to provide suitable material for sub-base, | | | | necessary where the path has to be raised, for |
| base and surfacing. Borrow pits may still have a use | | | | example above a high water table. In all other cases, |
| in some locations where the natural soils are weak or | | | | it should be possible either to simply roll the surfacing |
| particularly organic and lacking granular quality. They | | | | into place right up to and including the untreated edge |
| are the traditional method of supplying material for | | | | soils to form the path. |
| stalkers' paths in the uplands of Scotland. These | | | | Uphill and downhill use |
| trackside mini quarries have now themselves become | | | | There is a physical and a psychological difference |
| valuable habitats. | | | | between cycling uphill and cycling downhill, both of |
| The location of the pit is chosen by careful inspection | | | | which tend to make downhill cycling the more |
| of the ground near to the path, and then by sinking a | | | | damaging to cycle tracks. |
| crowbar into the ground to find where there are | | | | Physically, the added braking when cycling downhill will |
| stony deposits near the surface. The material is then | | | | more cause more surface damage than does the |
| dug out using a crowbar, pick and shovel, and moved | | | | slow and careful tiring pedal uphill. Travelling downhill |
| in buckets or by power carrier to the path. | | | | the bike will also slide, dislodging any loose stones or |
| Depending on the depth of the stony deposits, the | | | | earth. Cyclists tend to move more slowly when |
| pit may be several metres square and up to 1m | | | | climbing uphill, because it is tiring, and the line of sight |
| deep. For safety reasons, pits must not be dug | | | | is limited to the area immediately in front. |
| deeper than 1m, and no 'tunnelling' should be done. In | | | | Downhill speed and wear is much more difficult to |
| suitable material, the sides of the pit should be stable, | | | | control. The view down is often clearer, and the line |
| as any liability to slump would indicate that the | | | | of path can more easily be seen encouraging |
| material was unsuitable for surfacing. When 'worked | | | | dangerous speed. Cyclists going downhill tend to be in |
| out', the pit is backfilled with the weak or organic | | | | a hurry, either racing each other, or just speeding for |
| material from the path, and covered with clumps of | | | | the thrill of it, |
| vegetation. Within a few days, the site of the pit | | | | With these factors in mind a harder path finish and a |
| should be hard to spot. Other borrow pits are dug as | | | | grippier surface will be required on all slopes, as a |
| necessary for other sections of path. | | | | downhill in one direction will be uphill on the return. |
| This method of working is cost-effective on remote | | | | Another factor to consider will be the number of |
| rural tracks, and for the sensitive and detailed type | | | | cyclists who need or choose to walk the slopes and |
| of path construction which these sites require. The | | | | extra width of track will be needed on slopes to |
| natural variety in locally-won material means that the | | | | keep all users safe. Whilst a mix ratio of 50:1 should |
| path has a very natural look and feel, as opposed to | | | | be adequate for normal path construction, increasing |
| a path constructed of imported quarried stone or | | | | the SMR ratio to 40:1 for track slopes will be |
| recycled type 1 aggregate. | | | | necessary. |