Pedestrian suspension bridges for valley, canyon and stream crossings that need no intermediate piers: design, steel fabrication and installation. The deciding items are anchor capacity, sway control and access conditions.
The problem
In deep valleys and in stream beds with high flow, building an intermediate pier is often either impossible or disproportionately expensive: reaching the foundation level, bringing machinery down and working in the bed are risky and depend on the season. At such crossings, pedestrian suspension bridges built with cables tensioned between the two banks span the gap without intermediate piers and sit in the landscape with minimal intervention. They are used on hiking routes, rural settlement links, tourism routes and operational crossings at facilities.
The real problem is not load capacity but behaviour. A light, flexible structure sways with the rhythm of walking and with the wind; even if the sway does not bring the structure down, it makes users feel unsafe and causes fatigue in the connections. The second is anchorage: all the load gathers at the two banks, so the rock or soil quality at those two points decides the project. Signs of deterioration: rust and cracks at the anchor head, broken cable wires, slip marks at clamps, rot in the deck, settlement at the tower base.
How we decide
The data we measure and compile: span and level difference between the banks, rock quality and discontinuity orientation at the anchor points, flood level and bed mobility, prevailing wind direction and speed, expected pedestrian density, seismic parameters, access and material transport options, snow and ice load.
| Observation | Criterion | Decision |
|---|---|---|
| Sound rock on both banks | Anchor capacity is proven by pull-out testing | Rock-anchored solution |
| Banks covered with overburden soil | Rock is deep, anchor length grows | Reinforced concrete anchor block or deep anchor |
| Long span with a level difference | Sag and deck gradient make use difficult | Different tower heights |
| High pedestrian density | Sway may exceed the comfort limit | Deck stiffness and stabilizing cables |
| Prevailing wind and a narrow valley | High risk of lateral sway | Lower stabilizing cables, open-mesh deck |
| Bed rises in floods | Deck soffit close to the flood level | Raising the level or moving the towers |
The starting point of the design is anchor capacity; cable diameter, tower height and deck weight are calculated from it. Earthquake action enters under the applicable seismic code (TBDY 2018 in Türkiye); anchors are installed to the principles of EN 1537.
System family
| System | When suitable | Source |
|---|---|---|
| Main cable, hanger rope, clamps | Load-bearing arrangement | Artusa manufacturing and supply |
| Steel tower and bearing fabrication | Level difference and sag arrangement | Artusa manufacturing |
| Steel grating or timber deck | By use and maintenance preference | Artusa manufacturing |
| Handrail and lateral safety net | Pedestrian safety | Artusa manufacturing |
| Rock anchor and anchor block | Load-bearing connection at the banks | Artusa installation |
| Lower and lateral stabilizing cables | Sway control | Artusa manufacturing |
Corrosion protection is defined by hot-dip galvanizing under EN ISO 1461 and, for ropes, by the choice of coating class. The expected service life and maintenance interval are written in the project file: service life and warranty (Turkish).
Installation
Work proceeds in parallel on both banks. First comes the topographic survey and setting out of the anchor points, then anchor drilling, grouting and pull-out tests. Once the test results are accepted, towers and bearings are set, the main cables are pulled across and tensioned in a controlled way. Hanger ropes are fitted, deck modules placed, handrail and safety net installed. In the final stage the geometry is measured and cable tensions are compared with the design.
The first line across the banks, deck installation and cable work are carried out by experienced specialists on rope access; the work-at-height arrangement is set up under EN 795 and EN 365. Checkpoints: anchor drilling and grouting record, pull-out test results, tower verticality, cable sag and tension, clamp torque, hanger rope lengths, deck level and gradient.
Acceptance and maintenance
Measured at handover: as-built geometry (span, sag, deck level and gradient), anchor pull-out test reports, cable material certificates and breaking loads, clamp torque list, weld inspections, galvanizing thickness measurements, handrail and net openings, and the service load limit set in writing. A sign with the load limit and rules of use is placed at the entrance.
Maintenance consists of an annual visual inspection and a detailed inspection. Checked: broken wires and corrosion in the cables, clamp slip, rust and cracks at anchor heads, deck elements, connection torque, handrail integrity, settlement at the tower base. After a flood, an earthquake or unusual loading, the geometry is measured again and compared with the first acceptance values.
Frequently asked
- Is an intermediate pier really not needed? No; the load is transferred to the anchors on the two banks. In return, the project depends on the capacity at those two points, and that capacity is proven by anchor pull-out testing.
- Does the bridge sway? As a flexible structure, some movement is natural. Comfort is decided by deck stiffness and the stabilizing cables; these items are dimensioned separately.
- What information is needed for a quotation? Span, level difference, soil information at the anchor points, type of use and access conditions. The list: what data is needed for a quotation (Turkish); the measurement headings: what is measured on site (Turkish).
Field record
1 project in this family in our records: Uzbekistan. Under confidentiality agreements, project and client names are not published.