[EN] Timely Guardrail Repair: Road Safety and Resource Efficiency | G·SAVE Part 3

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When guardrail inspection and maintenance are delayed, a facility intended to limit the consequences of a vehicle collision may no longer perform as intended. Section loss caused by corrosion, missing fasteners, and deformation remaining after an impact are all priority items for safety inspections.

South Korea’s Ministry of Land, Infrastructure and Transport explains in its Guidelines for the Installation and Management of Road Safety Facilities that damaged or deficient barriers left unattended may fail to perform adequately in a collision, potentially leading to a serious accident. This is why the guidelines call for inspections of corrosion, rail deformation and damage, and the connections between posts and horizontal members, followed by restoration of facilities whose function has deteriorated.

Reducing the accident risks associated with inadequate maintenance requires inspection and repair to be included in maintenance plans after installation. It is particularly important to reduce the number of locations where identified damage remains unresolved because of budget constraints or construction conditions.

Road authorities must address these issues across long routes within limited budgets. Even along the same route, some members require replacement after impact damage, while others can remain in service after corrosion repair. Selecting a maintenance method according to the condition of each asset allows serviceable steel to be retained and funding to be directed toward locations where replacement is urgent.

Guardrail replacement involves more than purchasing new rails. It also requires dismantling and removing existing members, transport and disposal, installation crews, and equipment. Traffic control and delays to road users must also be considered. Assessing the economics of on-site repair therefore requires examination of these differences in construction processes as well as material prices.

KEMP’s G·SAVE restores corrosion protection by preparing the surface of existing hot-dip galvanized members in place and forming a zinc-based inorganic protective layer. It supplements corrosion protection on members that retain their shape and effective cross-section, enabling the existing steel to remain in service.

Rails with impact deformation or substantial section loss, together with damaged or missing fasteners, are identified for replacement. Coordinating structural and connection repairs with corrosion maintenance is fundamental to guardrail asset management.

Previous painting also affects the repair process. Any existing paint layer must be completely removed before G·SAVE is applied. For the first repair of a hot-dip galvanized member that has not been painted, stripping an existing paint film is unnecessary, allowing the work to focus on surface preparation appropriate to the corrosion condition and formation of the protective layer.

The on-site construction cost analysis gives the following costs for a single repair or replacement intervention.

Guardrail type	G·SAVE repair	Replacement	Repair cost as a share of replacement cost
2W guardrail	KRW 19,509/m	KRW 81,196/m	Approx. 24.0%
3W guardrail	KRW 25,000/m	KRW 87,747/m	Approx. 28.5%

Costing basis: roadside guardrails, treatment of the full front face, 4 m spans, including VAT. Figures are from the 2024 cost analysis.

The cost of a single intervention helps determine how much of a route can be maintained within the current year’s budget. Long-term maintenance planning also needs to consider initial installation costs, subsequent repair or replacement costs, and the service period assumed for each method.

The life-cycle model, including initial installation, assumed 15 years of service after new installation and 12 years after repair. The “initial installation followed by repair” option therefore covered 27 years, while “initial installation followed by replacement” covered 30 years. Average annual costs were calculated by dividing the total cost of each option by its respective period.

Guardrail type	Initial installation + G·SAVE repair	Initial installation + replacement	Reduction in average annual cost
2W guardrail	KRW 3,730/m/year	KRW 5,494/m/year	Approx. 32.1%
3W guardrail	KRW 4,176/m/year	KRW 5,941/m/year	Approx. 29.7%

These figures divide the costs of initial installation, subsequent repair or replacement, and disposal by the analysis period and include VAT. Project costs for an individual site are calculated according to the length to be repaired, the extent of surface preparation, the presence of existing paint, and traffic management requirements.

The benefits of timely repair extend beyond cost. Keeping existing steel in service reduces the corresponding demand for new steel manufacture and hot-dip galvanizing. Alongside recycling removed steel, there is good reason to consider retaining serviceable members in place.

Carbon emissions were compared for the production and galvanizing of new members and the operation of equipment used for G·SAVE on-site repair.

KEMP calculated production-stage emissions for new members using 2.00 kg CO₂/kg for steel manufacture and 0.23 kg CO₂/kg for hot-dip galvanizing. Together, the two processes account for 2.23 kg CO₂ per kilogram of steel. Manufacturing and galvanizing one new 60 kg member therefore produces a calculated 133.8 kg CO₂.

G·SAVE retains the existing member, avoiding the need to manufacture and hot-dip galvanize a new member in its place. KEMP calculated emissions from operating the generators, vehicles, and other equipment used for on-site repair at 0.9 kg CO₂ per 60 kg member.

Applying the same basis to 1 km of median barrier containing 46 tonnes of steel gives the following results.

Processes compared	CO₂ emissions per 60 kg member	CO₂ emissions for 1 km containing 46 tonnes of steel
Steel manufacture and hot-dip galvanizing of new members	133.8 kg	102.58 tonnes
Operation of G·SAVE repair equipment	0.9 kg	0.69 tonnes

For the processes compared under these conditions, carbon emissions decrease from 102.58 tonnes to 0.69 tonnes, a reduction of approximately 99.3%. These figures reflect the difference between producing and galvanizing new steel and retaining existing members through on-site repair.

Calculation scope: production of new members compared with operation of on-site repair equipment. Manufacture and transport of the repair materials, among other items, require separate assessment.

Repair that keeps existing steel in service reduces the resources and energy needed to manufacture new members. Timely maintenance of repairable members increases the extent to which new material production can be avoided and can also reduce the logistics required to remove dismantled members and deliver replacements. A site survey that distinguishes replacement quantities from repair quantities provides a basis for managing both budgets and carbon emissions.

Productivity and work-zone management are also important during on-site construction. The G·SAVE vehicle-mounted continuous coating system is configured to work while moving along extended guardrail sections. Field application in Ulsan demonstrated a coating repair output of 1.1 km per day.

Working without dismantling existing members can reduce the handling and transport of heavy components and the need for reinstallation. It also helps minimize sections left without a barrier between removal and replacement. Work sections must be planned around traffic volumes and available space, with safety managed for both workers and passing vehicles.

The equipment incorporates a coating booth and an extraction unit to control overspray during application. Environmental benefits need to be assessed through both reduced production of new materials and environmental controls during on-site work.

The condition after application was also inspected. Records from a November 2023 inspection of a section treated in December 2022 reported no coating delamination or additional corrosion. KEMP subsequently carried out demonstrations over a cumulative distance exceeding 10 km with multiple local authorities, confirming performance in field applications. Based on this application experience, G·SAVE is available for supply and on-site application to repair aging hot-dip galvanized infrastructure.

Guardrail maintenance plans should reflect actual corrosion, impact damage, and connection condition as well as the installation year. Sections exposed to more corrosive conditions, such as coastal environments or deicing salts, may need maintenance at different times even when the facilities are the same age. Using inspection findings to identify the scope and quantities for urgent replacement, connection repairs, and preventive corrosion maintenance makes budget priorities clearer.

Within this approach, G·SAVE on-site repair restores corrosion protection to hot-dip galvanized members that can remain in service. It reduces unnecessary wholesale replacement, allowing budgets to be allocated to needed maintenance, while continued use of existing steel reduces the resource demand and carbon emissions associated with new production.

Applications extend beyond road guardrails. On-site repair can also be considered for steel masts on high-speed rail lines, transmission tower members, posts, and hot-dip galvanized steel structures at industrial facilities. Where dismantling and reinstallation are costly or operational shutdowns are difficult, a maintenance strategy that restores corrosion protection in place after confirming structural integrity becomes particularly valuable.

To discuss the scope of application and a construction plan with KEMP, prepare overview photographs and close-ups of corrosion and connections, together with the installation year, previous painting history, and the length of the proposed repair section.

Sources: on-site construction cost analysis, field application records, and carbon emissions calculations in the 2024 final report, PDF pages 11, 32–35, and 83–86. Cost analysis: 한국기업연구원. Before and after photographs: Iksan G·SAVE field application records. Connection survey photograph: 2019 comprehensive guardrail survey.
Guidelines for the Installation and Management of Road Safety Facilities

G·SAVE Part 1: Field Applications and Evidence · G·SAVE Part 2: Guardrail Safety After Installation
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