Planning & Design

I. Pre-planning: data research and demand analysis

1. Multi-source data collection

Status quo research:

● Geographic Information (GIS): topography, hydrology, geological conditions (e.g. soft ground distribution);

● Traffic basic data: existing road grade, number of lanes, average daily traffic flow (obtained through geomagnetic sensors, UAV aerial photography);

● Population and land use planning: regional population density, nature of land use (residential / commercial / industrial), future development plans.

Demand forecasting:

● A four-phase approach (trip generation, distribution, modal split, and flow allocation) was used to forecast transportation demand over the next 10-20 years;

● Combined with the city's master plan, analyze the carrying demand of roads for new population and industrial parks.

2. Problem diagnosis and target setting

Identify the pain points of the existing road network: congested nodes, accident-prone road sections, cut-off roads, lack of non-motorized roads, etc;

Set planning objectives:

● Short-term: alleviate peak congestion and improve transit sharing ratio;

● Long-term: to build a “15-minute living circle” road network to support the expansion of urban space.

II. Road network structure planning

1. Design of hierarchical road network system

2. Functional road design

Transit priority lanes:

● Open up separate right-of-way BRT lanes with smart signal priority (extended green time when transit approaches);

● Harbor-type bus stops to reduce the impact of stops on arterial traffic.

Slow-moving pedestrian system:

● Continuous through non-motorized lanes (width ≥1.5m) and pedestrian lanes (width ≥2m), distinguished by colored paving;

● Crossing facilities are encrypted (e.g. crosswalk or footbridge every 300-500m), equipped with pedestrian crossing buttons and countdown lights.

Freight access:

● Planning of outer ring road to avoid large trucks crossing the city center;

● Nighttime access policy to reduce the disturbance to residents' life.

III. Key Node Design

1. Intersection optimization

Drainage design:

● Widen inlet lanes to add dedicated left turn / right turn lanes, and install guide islands to direct traffic;

● Smaller intersections use “reduced intersection area” design to shorten pedestrian crossing distance.

signal control:

● Complex intersections use adaptive signaling to adjust phase timing in real time;

● Coordinate the green light time of adjacent intersections to form a “green wave band” (e.g. when the speed of the main road is 50km/h, the green light interval is calculated according to the distance).

2. Three-dimensional transportation facilities

Footbridge / Underpass:

● Install footbridges with elevators in dense commercial areas and near schools to enhance accessibility;

● Underpasses combined with commercial development (e.g. connecting subway stations with shopping malls) to improve space utilization.

overpasses / tunnels:

● Cloverleaf interchanges are used where highways intersect with urban roads to reduce conflict points;

● When crossing mountains or rivers, the tunnel option is prioritized to protect the ecological landscape.

IV. Sustainable and Humanized Design

1. Integration of sponge city concept

● The sidewalk adopts permeable bricks (permeability ≥ 0.15mm/s), and the rainwater sinks into the green belt infiltration through blind ditches;

● The green belt of the road is set up with concave green space to retain rainwater and purify pollutants.

2. Ecology and landscape design

Plant configuration:

● Street trees choose varieties with good shading effect and anti-pollution (e.g., hanging bell tree, camphor tree);

● Separation zone planting low-maintenance flowers (e.g. cosmos) to enhance the aesthetics of the road.

Cultural elements are implanted:

● Historic district roads are paved with antique paving, and the street lamp style echoes regional culture;

● Tourism roads set up viewing platforms and signage systems to connect attractions along the route.

3. Barrier-free and ageing-friendly design

● The sidewalk edge slope adopts three-face slope design, with a slope ≤ 1:20;

● Blind alleys are continuous and uninterrupted, avoiding obstacles such as tree cavities and utility poles;

● Bus stops are equipped with seats and rain shelters to facilitate the elderly waiting for buses.

V. Digital tools and technology application

1. Traffic Simulation

Use Vissim, TransCAD and other software to simulate the planning scheme, the evaluation indexes include:

● capacity (hourly flow of lanes), delay time, queue length;

● Carbon emission prediction (vehicle fuel consumption simulation at different speeds).

Case: The simulation of a city's main road widening program shows that adding 2 lanes can reduce peak delays by 40%.

2. Application of BIM technology in the whole process

● Road 3D modeling: accurately present the spatial relationship of roadbed, bridge and pipeline;

● construction collision detection: discovering the conflict between underground pipe network and roadbed design in advance, reducing on-site changes.

3. Intelligent monitoring of pre-burial

● Reserve IoT sensor installation interfaces (e.g. traffic flow radar, weather monitoring equipment) in key road sections to lay the foundation for later intelligent management.

VI. Implementation and Evaluation

1. Phased construction strategy

● Prioritize the opening of broken roads and widening of bottleneck sections to quickly improve road network connectivity in the short term;

● Synchronize the construction of supporting roads and public transportation facilities in the long term with the development of new areas.

2. Effectiveness assessment indicators

● Quantitative indicators: road network density (urban built-up area ≥8km/km²), average commuting time (target ≤30 minutes), public transportation punctuality rate (≥90%);

● Qualitative Indicators: Pedestrian / Driver Satisfaction Survey, Decrease in Traffic Accident Rate.

Conclusion

Road planning and design need to balance functionality, safety and sustainability, and through the whole process control of “data diagnosis - hierarchical planning - fine design - technology empowerment”, to create a “highly efficient, accessible, green and low-carbon, people-oriented” road network. Through the whole process of “data diagnosis - hierarchical planning - fine design - technology empowerment”, we can create “highly efficient, accessible, green, low-carbon and people-oriented” road systems. For example, in the planning of new cities, intelligent networked roads can be laid out in advance to reserve interfaces, while the transformation of old cities focuses on micro-renewal and optimization of traffic micro-circulation, and ultimately realizes the dynamic synergy between roads and urban development.