Climate Change Has Been and Is Clearly Existing on National Highways in the Central Region:

The overall effectiveness of standards can be significantly enhanced if combined with financial incentives and consumer information.

e) Transport demand management

Demand management is a measure taken to improve traffic congestion and air pollution on roads by reducing traffic density. Providing incentives to users to reduce the number of vehicles on the road, changing the frequency, form, location, route and travel time.

DISCUSS

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(i). Research on the impact of climate change on the transport sector and other sectors

In general, the road transport sector and other sectors are similar in studying the impacts of climate change today, using a systemic and interdisciplinary approach based on the ecosystem. According to the " Guidelines for assessing the impacts of climate change and adaptation solutions " implemented by the Institute of Meteorology, Hydrology and Environment in 2011, this approach simply includes the following steps:

(+) First, assess the impact of climate change at the present time (corresponding to current economic, social and environmental conditions);

(+) Then assess the impact of future climate change (corresponding to climate change scenarios and future economic, social and environmental conditions - according to the assessment time frame);

(+) Assessment of future climate change impacts should be carried out under different climate change and sea level rise scenarios and different local socio-economic development scenarios;

(+) Climate change impact assessment needs to be updated when climate change and sea level rise scenarios are updated or when there are important adjustments to strategies, policies, plans, and sectoral development planning and local socio-economic development.

Regarding the methods used in assessing the impact of climate change, survey, statistics, investigation and modeling methods are used.

Regarding the research space of climate change in the road transport sector, there is a difference compared to other sectors and fields in that the research space of the road transport sector spans across different geographical areas, different ecosystems, different river basins, different economic - social - environmental forms...; the research scope on both sides of the road is narrow, so assessing the impact of climate change is difficult.

For the agricultural sector, when affected by climate change, the yield of harvested agricultural products will be reduced, which will immediately affect the lives of farmers; on the contrary, for the road transport sector, when affected by climate change, a section of road may be flooded, landslides may occur... causing traffic obstruction and affecting traffic activities in the area but not directly affecting people's lives. Therefore, identifying the impact as well as assessing the level of impact of climate change is currently controversial.

The impacts of climate change can cause damage to other industries but can also create certain benefits. For example, flooding will cause crop failure but the land will be supplemented with nutrient-rich alluvium; flooding is also an opportunity to develop aquaculture... For the transport industry, the impacts of climate change only cause damage to the road network.

(ii). Similarities and differences between road sections on the same route

Through the investigation and survey data on the scope of the two research routes of the thesis, we can see the similarities and differences of road sections on the same route when affected by climate change as follows:

(-) Alike:

(+) Both are located in the same geographical area, terrain, and climate

(+) Both are affected by the same climatic factors (wind, rain, temperature...) (+) Both are designed, constructed and maintained according to the same standards and processes

(+) The types of land affected by climate change are the same (for example, roads in the plains are mainly flooded when affected by climate change).

(+) Solutions to respond to climate change are the same

(-) Different:

(+) The underlying geology may be different (+) The hydrological regime may be different

(+) Mining vehicle load may vary

(+) The level of impact of climate change is different (for example, section Km0 - Km25 is flooded more deeply and frequently than the remaining sections on National Highway 49B)

However, to determine the level of impact of leaks, whether they are severe or mild, serious or not, between sections of the same route, it is not only based on annual damage statistics but also other factors such as whether the design standards for each section are appropriate; whether the construction process ensures the same quality; and the vehicle load on each section is different. This is an issue that the Ministry of Transport is currently researching to determine the cause of damage and solutions to improve the road's operating life.

(iii). Similarities and differences between the two routes

A specific study of the two routes QL49B and Ho Chi Minh City shows the similarities and differences when affected by climate change as follows:

(-) Alike:

(+) Both are affected by the same climatic factors (wind, rain, temperature...)

(+) The impacts of climate change all cause certain damage to the road, affecting the road's operating life; costly maintenance and repair costs; affecting the transport capacity and safety of road users.

(-) Different:

(+) Designed, constructed and maintained according to different standards and procedures because of different road grades

(+) Geographical location, terrain, geology, climate and hydrological conditions are different.

(+) Different vehicle loads due to routes connecting different socio-economic centers

(+) The type of impact of climate change is different depending on geographical, climatic and topographic characteristics: National Highway 49B is an estuary area so it is strongly affected.

of flooding, sea erosion and inundation due to rising sea levels. Ho Chi Minh Road is mainly affected by landslides and flash floods because it is located in a mountainous area and is strongly affected by rainfall regimes that tend to increase in intensity due to climate change.

(+) Solutions to respond to climate change are different for each route.

CONCLUSION AND RECOMMENDATIONS

Through the specific research results in chapters 1, 2 and 3, the thesis comes to the following conclusions and recommendations:

CONCLUDE

1. Climate change has been clearly present on national highways in the Central region:

- Temperature change trend tends to increase in the entire Central region except Khe Sanh - Quang Tri. Absolute maximum temperature tends to increase by an average of 0.025 0 C/year.

- The lowest temperature in the Central region from Thanh Hoa to Deo Ngang increases insignificantly or tends to decrease. From Deo Ngang inwards, the increasing trend is faster.

- Daily temperature difference, highest and lowest monthly temperature difference tend to increase across the region.

- Average annual rainfall from Thanh Hoa to Deo Ngang tends to increase in Thanh Hoa and Nghe An but decrease in Ha Tinh.

- The average annual rainfall from Deo Ngang to Quang Nam tends to increase, especially strongly in the Hue area. The average annual rainfall increase rate is about 10.3mm/year compared to the maximum rainfall in 1999 in Hue.

- The highest sea level rise due to climate change in 2100 for the National Highway 49B area is about 60 - 71 cm for the average scenario.

2. The increase in natural disasters is the most obvious and serious manifestation of climate change in the Central region.

2.1. The following major natural disasters will pose a threat to National Highway 49B (coastal) in the future:

- Storms with their increasing intensity and irregularity will pose a great risk of destroying structures along the route.

- Increased rainfall intensity in the future will cause coastal erosion and landslides; flooding and landslides on slopes; damage to road surfaces, bridges, signs and other works on the route.

- Rising sea levels increase the risk of flooding; seawater accelerates the corrosion of concrete, reinforced concrete bridges, culverts, and asphalt roads. Rising sea levels also increase the risk of coastal erosion in the Thuan An - Hoa Duong section and Tu Hien estuary.

- Saltwater intrusion will corrode concrete, reinforced concrete bridges, culverts, and asphalt roads. However, this area currently has a system of sand dykes and casuarinas to block waves, and on the Huong River, Thao Long saltwater dam has been built, limiting the impact of saltwater intrusion.

- Increased temperature, prolonged, increased temperature difference during the day, increased temperature difference between seasons will cause continuous tensile and compressive stresses in the structure and eventually destroy the construction due to the phenomenon of "fatigue". Increased temperature also increases fuel consumption of vehicles, tires wear out and age quickly, traffic participants get tired on hot days leading to unsafe traffic. Increased temperature also increases humidity, increases seawater vapor affecting constructions on the route.

- Floods on the Huong River combined with high tides cause inundation, landslides on slopes; damage to road surfaces, bridges and culverts.

- Landslides on the section Km94+00 - Km104+800 will continue to be at risk due to the increasing frequency and intensity of rain and storms.

2.2. The following major natural disasters will pose a threat to the Ho Chi Minh Trail (mountainous areas) in the future:

- Storms and storm circulations with stronger intensity will increase the risk of landslides and flash floods affecting roads and structures along the route.

- Heavy rain with increasing intensity will cause soil erosion, flooding, landslides on slopes; damage to road surfaces, bridges, signs and other works on the route.

- Increased temperature, prolonged temperature difference during the day, increased temperature difference between seasons will cause continuous tensile and compressive stresses in the structure and eventually destroy the structure due to the phenomenon of "fatigue". Increased temperature also increases fuel consumption.

Vehicle fuel, tires wear out and age quickly, traffic participants get tired on hot days leading to unsafe traffic.

- Floods on rivers cause inundation, landslides on slopes; damage to road surfaces, damage to bridge and culvert systems.

- Flash floods on rivers can completely destroy a section of road, bridge, or culvert when the flood carries soil and rocks across the route.

- Slope landslides continue to occur at many locations on the 9km long Da Deo-Khe Gat pass; the 31km long Cong Troi pass (Ngan Thuy, Le Thuy, Quang Binh and Huong Lap, Huong Hoa, Quang Tri); the 22km long Sa Mu pass (Huong Phung, Huong Hoa, Quang Tri); the over 25km long Hai Ham pass (A Roang, A Luoi, Thua Thien Hue); the 25km long Song Bung pass (Dong Giang and Nam Giang, Quang Nam) due to the increasing frequency and intensity of rain and storms.

3. Climate change response orientations for national highways in the Central region.

3.1. Solutions to adapt to climate change.

3.1.1. Policy solutions and investment demand calculation.

a. Policy solution

Policy solutions are the most important solutions in responding to climate change in the transport sector because they can adjust the sector's development planning, investment in the construction of transport infrastructure, types and quality of vehicles, fuel used by vehicles... in a direction that is beneficial for reducing greenhouse gas emissions and increasing the adaptability of road transport infrastructure to climate change.

b. Solution for investment capital needs

Finance is always an important issue in every program, so it is necessary to carefully study investment needs and investment capital sources to respond to climate change in a way that is both economical and suitable for socio-economic development.

3.1.2. Solutions to cope with the impacts of extreme weather phenomena on road transport

a. Policy and propaganda solutions

Use policy tools in promulgating legal regulations on protecting road traffic infrastructure from the impacts of extreme weather events.

Organize education, disseminate knowledge and legal regulations on potential hazards to road transport projects as well as methods of adaptation and mitigation of impacts to management levels, as well as to each locality and people where the route passes through.

b.Technological solutions for landslide treatment

Classify landslides according to scale and provide temporary solutions to ensure traffic and permanent treatment measures.

c. Solutions to prevent saltwater intrusion

This solution combines all elements from planning, design to the use of seawater resistant materials to increase the stability of the structure against the impact of rising sea levels on coastal structures.

d. Solutions to prevent saltwater intrusion

3.1.3. Solutions on road traffic design standards

The solution to design road transport is the solution to analyze a series of statistical data on hydrometeorological conditions to come up with appropriate design options. To adapt to climate change, the analysis and forecasting of data must have new approaches to forecast unusual weather factors in the future.

3.2. Solutions to minimize the impact of climate change

Many technologies and strategies are proposed to reduce and ultimately eliminate greenhouse gas emissions from transportation. Greenhouse gas emissions can be reduced by the following four main groups of solutions:

(+) Reduce vehicle load, thereby reducing operating fuel;

(+) Increase fuel efficiency by improving drive system efficiency and reducing energy loss;

(+) Switch to low-carbon fuels (alternative fuels); (+) Solutions for traffic management and organization.