Urban road side strip wedge-shaped entrance and exit design method

Abstract

The application provides a design method for a wedge-shaped entrance and exit of a city road side strip, which establishes a model of the wedge-shaped entrance and exit and a mathematical relation of the model according to analysis of a vehicle driving track, determines basic parameters and performs checking calculation based on the mathematical relation in combination with technical indexes and cross section conditions of the road, and finally determines each size parameter of the wedge-shaped entrance and exit meeting the requirements. The method provided by the application fills the blank of design, implementation and reconstruction of the wedge-shaped entrance and exit of the city road, can provide a scientific and reasonable basis for the wedge-shaped entrance and exit opening of a city traffic trunk road main road, and the entrance and exit set by the method can safely, comfortably and quickly pass, effectively reduces the safety hidden danger caused by unreasonable opening setting, effectively channels the in and out traffic, and ensures the side strip landscape effect.

Description

Technical Field

[0001] This invention relates to the field of urban road engineering design, and in particular to a design method for wedge-shaped entrances and exits in the median strip of urban roads. Background Technology

[0002] Urban expressways and arterial roads form the backbone of the urban road traffic system. Although expressways and arterial roads are now common in major cities, the design of wedge-shaped entrances and exits in the median strips of expressways and arterial roads still needs further improvement.

[0003] Wedge-shaped openings in the median strips of expressways and arterial roads are unidirectional openings controlling access to and from the main road. These openings should ensure smooth vehicle entry and exit while guaranteeing driving safety and comfort. In practical application, wedge-shaped openings cannot be too large. On the one hand, if the opening is too large, traffic channelization is not obvious, failing to guarantee the function of controlling unidirectional traffic flow and negating the purpose of the wedge-shaped opening. On the other hand, if the opening is too large, the small wedge-shaped ends will significantly impact the aesthetics and create difficulties in the installation of ancillary facilities. Conversely, if the wedge-shaped opening is too small, traffic flow will be obstructed, easily causing traffic congestion and posing significant traffic safety hazards. Currently, the design of wedge-shaped entrances and exits on the main lanes of urban expressways and arterial roads lacks clear and unified methods and theoretical basis, and the current design of wedge-shaped openings is still relatively arbitrary and lacks scientific rigor.

[0004] Therefore, there is an urgent need for a design method for wedge-shaped entrances and exits in urban road medians to fill the gap in the method for determining entrance and exit dimensions during the design, implementation, and renovation of wedge-shaped urban roads, thereby providing a basis for the scientific and reasonable setting of entrances and exits in urban traffic arteries. Summary of the Invention

[0005] In view of the above, it is necessary to provide a design method for wedge-shaped entrances and exits in urban road medians. This method fills the gap in the design, implementation, and renovation of wedge-shaped entrances and exits in urban roads. It can provide a scientific and reasonable basis for the opening of wedge-shaped entrances and exits on the main roads of urban traffic arteries. Moreover, the entrances and exits set by this method can not only ensure safe, comfortable and fast passage, but also effectively reduce the safety hazards caused by unreasonable opening settings, while effectively channeling traffic and ensuring the landscape effect of the median.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A design method for wedge-shaped entrances and exits in urban road medians involves establishing a model of the wedge-shaped entrance and exit and its mathematical formula based on vehicle trajectory analysis. Based on these mathematical formulas, and considering the road's technical specifications and cross-sectional conditions, basic parameters are determined and verified. Finally, the dimensional parameters of the wedge-shaped entrance and exit that meet the requirements are determined. The specific steps are as follows:

[0008] Step 1: Based on the road technical standards and the standard cross-section layout of the road, determine the main line design speed V0, the side median width D, the distance d1 from the center line of the outermost lane of the main road to the side median, and the distance d2 from the center line of the innermost lane of the auxiliary road to the side median.

[0009] Step 2: Determine the basic parameters: nose radius r, lane width d, and speed coefficient k;

[0010] Step 3: Initially determine the chamfer radius R and the inlet / outlet gradient η, substitute them into calculation formulas (1)-(3), and calculate the limit value [R]' of the chamfer radius. Then increase η and recalculate until R < [R]' is satisfied, then proceed to the next step; where the calculation formulas (1)-(3) are:

[0011]

[0012] In the formula, L1 is the length of the wedge-shaped transition segment;

[0013] Step 4: Calculate the net width L0 of the wedge-shaped entrance / exit using formula (4). Substitute η back into the calculation and proceed to step 3 to re-verify R until L0 < [L0] is satisfied, then proceed to the next step; where [L0] is the limit value of the net width of the wedge-shaped entrance and exit, and the calculation formula (4) is:

[0014]

[0015] Step 5: Calculate the safe driving distance S0 at the wedge-shaped entrance / exit using formula (5), and calculate the length S of the straight segment of the driving trajectory at the wedge-shaped entrance using formula (6). If S0 > [S0] is not true, increase η and re-enter step 3; if S > [S] is not true, decrease R and re-enter step 3; if both S0 > [S0] and S > [S] are satisfied, then η and R are the values ​​that satisfy the conditions; where [S0] is the limit value of the safe driving distance at the wedge-shaped entrance / exit, and [S] is the limit value of the length of the straight segment of the driving trajectory at the wedge-shaped entrance. Formulas (5) and (6) are:

[0016]

[0017]

[0018] Step 6: Based on η and R determined in Step 5, calculate the basic parameters of the wedge-shaped entrance / exit planar dimensions: the length L1 of the wedge transition section and the tangent point road direction spacing L. Combined with the basic parameters r, R, and d proposed in Step 2, these are the structural parameter values ​​of the wedge-shaped entrance / exit. The length L1 of the wedge transition section is calculated using formula (1), and the tangent point road direction spacing L is calculated using formula (7). Formula (7) is...

[0019] L = L0 - 2·(L1 - r) (7).

[0020] Furthermore, in step 2, when determining the speed coefficient k, k is taken as 0.4 to 0.6.

[0021] Furthermore, when initially determining the chamfer radius R in step 3, it is necessary to satisfy R > [R], where [R] is the limit value of the chamfer radius.

[0022] Furthermore, in step 5, [S0] = V, where V is the running speed of the wedge-shaped inlet and outlet, V = k·V0.

[0023] Further, in step 5, [S] = V / 1.2, where V is the running speed of the wedge-shaped inlet and outlet, V = k·V0.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention analyzes the actual vehicle driving trajectory of wedge-shaped entrances and exits, combines factors such as vehicle driving safety and comfort with the functionality of wedge-shaped entrances and exits, and constructs a mathematical model of wedge-shaped entrance and exit design parameters. It proposes a design method for wedge-shaped entrances and exits in urban road medians based on functionality, safety, and comfort, thereby filling the gap in the method for determining the dimensions of wedge-shaped entrances and exits in urban roads for design, implementation, and renovation, and providing a basis for the scientific and rational design of median entrances and exits on urban traffic arteries.

[0026] 2. By using the method of this invention, combined with computational programming, the design parameters of the wedge-shaped entrance and exit can be determined simply, quickly, and conveniently, thereby enabling the design of the wedge-shaped entrance and exit. In addition, the wedge-shaped entrance and exit designed by this method can meet the requirements of vehicle safety and comfortable driving, and can effectively ensure the functionality of the wedge-shaped entrance and exit. The method is scientific, reasonable, and consistent with reality, and has strong feasibility, reliability, and recommendation. Attached Figure Description

[0027] Figure 1 This is a flowchart of the calculation process of the present invention.

[0028] Figure 2 This is a simplified model diagram of the wedge-shaped outlet (inlet) of the present invention.

[0029] Figure 3 This is a mathematical model diagram of the wedge-shaped outlet (inlet) of the present invention.

[0030] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0031] Please see Figures 1 to 3In a preferred embodiment of the present invention, a design method for a wedge-shaped entrance / exit in a median strip of an urban road is provided. Based on the analysis of vehicle driving trajectories, a model of the wedge-shaped entrance / exit and its mathematical relationship are established. Based on the mathematical relationship, combined with the road's technical indicators and cross-sectional conditions, basic parameters are determined and verified, and finally, the dimensional parameters of the wedge-shaped entrance / exit that meet the requirements are determined.

[0032] In this invention, the vehicle's trajectory is analyzed using the following method, and a wedge-shaped entrance / exit model and its mathematical relationships are established:

[0033] 1) Vehicle trajectory analysis and model establishment

[0034] (1) The process of a vehicle exiting the main road from the wedge-shaped exit:

[0035] First, drive to the outermost lane of the road according to the road exit advance notice or directional signs to prepare to leave. Combined with the exit confirmation sign, coast and slow down. When you reach the exit / exit position, observe whether it is safe to merge into the auxiliary lane and the situation ahead of the exit lane. Turn right into the wedge-shaped exit lane and be alert for the auxiliary lane merging situation. After merging into the auxiliary lane, straighten your direction and leave the exit.

[0036] (2) The process of a vehicle entering the main road from the wedge-shaped entrance:

[0037] First, based on the road conditions ahead on the auxiliary road (entrance advance notice or directional signs, drive to the innermost lane of the road) and prepare to enter. Maintain a constant speed in conjunction with the entrance confirmation signs. When you reach the entrance / exit position, observe whether it is safe to merge into the main road and the conditions ahead of the entry lane. Turn left into the wedge-shaped entrance lane and be alert to the merging situation into the main road. After merging into the outermost lane of the main road, straighten the steering wheel and accelerate to leave the entrance.

[0038] (3) Please refer to Figure 2 and Figure 3 Based on the driving trajectory of vehicles at the wedge-shaped entrance and exit of the side median strip, the driving trajectory is located in the center of the lane. Vehicles exiting (the entrance and exit are basically the same, only the direction is opposite; therefore, the entrance is referenced to the exit, and the following explanation uses the exit as an example) deceleration phase S. QA and exiting section S AB S AB Simplified to turning segment S R1 Straight segment S, Turning segment S R2 S R1 S R2 These are arcs with radii R1 and R2, respectively. The wedge-shaped transition section is extended to intersect the driving trajectory line at point C, and the driving trajectory line intersects the edge line of the auxiliary lane at point D. Set S... CD The wedge-shaped exit safety distance S0, as mentioned above, S determines driving comfort, while S0 primarily reflects driving safety. Deceleration phase S... QAThe starting velocity is the main line design velocity V0. To simplify the calculation, let S be... AB The running speed V of the section is a constant and is the same as the design speed of the auxiliary road. The speed V at point A is... A The velocity V at point B B Then V A =V B =V;

[0039] (4) Based on the design elements of the wedge-shaped entrance and exit dimensions: wedge transition section L1, end chamfer section L2, nose radius r, chamfer radius R, exit lane width d, entrance / exit transition rate η, side median width D, and wedge angle α, L0 and S, S AB 、S0.

[0040] 2) Establish a mathematical model and obtain the mathematical relationships within the model.

[0041] (1) From the geometric relationship of the wedge-shaped exit plane, we have:

[0042]

[0043] L0 = d / sinα - L1 + 2L2 - 2r,

[0044]

[0045] In the formula,

[0046] D – Side strip width (m);

[0047] α — Deflection angle of the transition segment (rad);

[0048] L—Distance between tangent points along the road (m);

[0049] L1—Length of the transition segment (m);

[0050] V – Operating speed of the wedge-shaped inlet / outlet (km / h);

[0051] k — velocity coefficient;

[0052] L0 — Net length of the wedge-shaped inlet / outlet cross section (m).

[0053] (2) Based on the simplified model of the wedge-shaped exit trajectory, establish the function calculation formula:

[0054]

[0055] In the formula,

[0056] W1—Width of the main road curb (m);

[0057] W2 — Width of the auxiliary road curb (m);

[0058] d1——The distance (m) from the center line of the outermost lane of the main road to the side median strip. The width of the outermost lane of the main road is set at 3.5m.

[0059] d2—The distance (m) from the center line of the innermost lane of the auxiliary road to the side median strip. The width of the innermost lane of the auxiliary road is set at 3.25m.

[0060] L0 — Clear width of wedge-shaped entrance / exit (m);

[0061] S—Length of the straight segment of the wedge-shaped travel trajectory (m);

[0062] S0 — Safe driving distance at wedge-shaped entrances and exits (m).

[0063] (3) Select key variables and establish the relationships L0 = f(η,d,D,r), S0 = f(η,d,D,R) and S = f(η,D,R). Substituting W1 = 0.5 and W2 = 0.25, we simplify to:

[0064]

[0065] To facilitate the calculation of dimensions for wedge-shaped opening design, η should be an integer or a single significant figure.

[0066] 3) Establish restrictions and control conditions

[0067] Considering driving comfort and safety factors, and taking into account the characteristics of the wedge-shaped opening (entry / exit), the wedge-shaped opening should ensure smooth vehicle entry and exit while guaranteeing driving safety and comfort. Therefore, limiting values ​​are determined for L0, S0, S, and R in this invention, namely [L0], [S0], [S], and [R], respectively. Wherein, [S0] represents the requirement for driving safety, [L0] represents the requirement for the functionality of the wedge-shaped opening, and [S] and [R] represent the requirements for driving comfort.

[0068] The wedge-shaped opening needs to have a certain width, but it cannot be too large. On the one hand, if the opening is too large, its traffic channeling effect will be insignificant, failing to guarantee the function of controlling the flow of vehicles in one direction, thus negating the purpose of the wedge-shaped opening. On the other hand, if the opening is too large and the wedge end is too small, it will have a significant impact on the landscape effect and the installation of ancillary facilities. To ensure the functionality of the wedge-shaped exit in controlling the flow of vehicles in one direction, while taking into account the landscape effect and the installation of ancillary facilities, based on practical application experience, [L0] is taken as 25m.

[0069] To ensure safe driving at the exit, this invention uses vehicle speed calculation in the exit section. Based on the actual situation, the operating speed is taken as the design speed of the auxiliary road. The design speed of the auxiliary road of urban roads is 0.4 to 0.6V0. Therefore, the actual operating speed is in the range of 40 to 20 km / h. The value of [S0] in this invention is taken as the operating speed V.

[0070] Regarding driving comfort, based on actual usage, and to ensure safety while minimizing the impact on the main road, and considering the operating speed, the [R] of this invention is typically set at a turning radius of 25-30, corresponding to the driving speed. A smaller value can be used at lower speeds, but generally [R] = 30. The straight section S of the exit segment is determined according to the minimum driving length requirements of the basic road segment planar elements, i.e.

[0071] In summary, the following relationship is established:

[0072]

[0073] The above is the model relationship of the wedge-shaped exit. According to the analysis of the actual driving situation of the wedge-shaped exit and entrance, the two are basically the same in the process of entering and exiting, only the direction is opposite. Therefore, the mathematical model relationship of the wedge-shaped entrance and exit is the same.

[0074] Therefore, based on the above analysis and mathematical model, the specific steps of the design method given in this invention are as follows:

[0075] Step 1: Based on the road technical standards and the standard cross-section layout of the road, determine the main line design speed V0, the side median width D, the distance d1 from the center line of the outermost lane of the main road to the side median, and the distance d2 from the center line of the innermost lane of the auxiliary road to the side median.

[0076] Step 2: Determine the basic parameters: nose radius r, lane width d, and speed coefficient k; where k is taken as 0.4 to 0.6.

[0077] Step 3: Initially determine the chamfer radius R and the inlet / outlet gradient η, substitute them into calculation formulas (1)-(3), and calculate the limit value [R]' of the chamfer radius. Then increase η and recalculate until R < [R]' is satisfied, then proceed to the next step; where the calculation formulas (1)-(3) are:

[0078]

[0079] In the formula, L1 is the length of the wedge-shaped transition segment.

[0080] It should be noted that when initially determining the chamfer radius R, it is necessary to satisfy R > [R], where [R] is the limiting value of the chamfer radius. For example, [R] can be 30.

[0081] Step 4: Calculate the net width L0 of the wedge-shaped entrance / exit using formula (4). Substitute η back into the calculation and proceed to step 3 to re-verify R until L0 < [L0] is satisfied, then proceed to the next step; where [L0] is the limit value of the net width of the wedge-shaped entrance and exit, and the calculation formula (4) is:

[0082]

[0083] Step 5: Calculate the safe driving distance S0 at the wedge-shaped entrance / exit using formula (5), and calculate the length S of the straight segment of the driving trajectory at the wedge-shaped entrance using formula (6). If S0 > [S0] is not true, increase η and re-enter step 3; if S > [S] is not true, decrease R and re-enter step 3; if both S0 > [S0] and S > [S] are satisfied, then η and R are the values ​​that satisfy the conditions; where [S0] is the limit value of the safe driving distance at the wedge-shaped entrance / exit, [S0] = V, [S] is the limit value of the length of the straight segment of the driving trajectory at the wedge-shaped entrance, [S] = V / 1.2, V is the speed of the wedge-shaped entrance / exit, V = k·V0, and formulas (5) and (6) are:

[0084]

[0085] Step 6: Based on η and R determined in Step 5, calculate the basic parameters of the wedge-shaped entrance / exit planar dimensions: the length L1 of the wedge transition section and the tangent point road direction spacing L. Combined with the basic parameters r, R, and d proposed in Step 2, these are the structural parameter values ​​of the wedge-shaped entrance / exit. The length L1 of the wedge transition section is calculated using formula (1), and the tangent point road direction spacing L is calculated using formula (7). Formula (7) is...

[0086] L = L0 - 2·(L1 - r) (7).

[0087] To fully illustrate the design method provided by this invention, the following embodiments are provided for further explanation:

[0088] Example 1

[0089] A main road in a city is a standard six-lane road in both directions, with a design speed of 50 km / h, a road red line width of 50 m, a four-slab cross section, a main lane width of 11.5 m, a side lane width of 2 m, and an auxiliary lane width of 7 m.

[0090] ① Based on the cross-sectional layout, we know that: V0 = 50km / h, D = 2m, W1 = 0.5m, W2 = 0.25m, d1 = 2.25m, d2 = 1.875m;

[0091] ② The basic parameters are initially determined to be r = 0.5m, d = 4.5m, and k = 0.5;

[0092] ③ It is initially determined that R is 40m and η is 10. According to the calculation formula (1)-(3), [R]'=198.01, which satisfies R<[R]', so proceed to the next step;

[0093] ④ Calculate L0 = 44.274 > 25 using formula (4), which does not satisfy L0 < [L0], so adjust η and recalculate;

[0094] ⑤ Take R as 40m and η as 5. Recalculate according to formulas (1)-(3). [R]' = 48.03, which satisfies R < [R]'. Proceed to the next step.

[0095] ⑥ Calculate L0 = 22.045 < 25 using formula (4), which satisfies L0 < [L0], and proceed to the next step;

[0096] ⑦ Calculate S0 = 34.125 > V = 25 using formula (5), which satisfies S0 > [S0]; calculate S = 25.482 > V / 1.2 = 20.833 using formula (6), which satisfies S > [S];

[0097] ⑧ The dimensions of the wedge-shaped inlet / outlet plane are: R = 40, r = 0.5, L1 = 10, L = 12.95, d = 4.5.

[0098] Example 2:

[0099] A main road in a city is a standard eight-lane road in both directions, with a design speed of 60 km / h, a road red line width of 60 m, a four-slab cross-section, a main lane width of 15.5 m, a side lane width of 2.75 m, and an auxiliary lane width of 6 m.

[0100] ① Based on the cross-sectional layout, we know that: V0 = 60km / h, D = 2.75m, W1 = 0.5m, W2 = 0.25m, d1 = 2.25m, d2 = 1.875m;

[0101] ② The basic parameters are initially determined to be r = 0.5m, d = 4.5m, and k = 0.5;

[0102] ③ It is initially determined that R is 60m and η is 4. According to the calculation formula (1)-(3), [R]'=53.69, which does not satisfy R<[R]'. R is adjusted and recalculated.

[0103] ④ R is recalculated to 50. According to the calculation formula (1)-(3), [R]' = 53.69, which satisfies R < [R]'. Proceed to the next step.

[0104] ⑤ Calculate L0 = 14.667 < 25 using formula (4), which satisfies L0 < [L0], and proceed to the next step;

[0105] ⑥ Calculate S0 = 30.582 > V = 30 using formula (5), which satisfies S0 > [S0]; calculate S = 15.997 < V / 1.2 = 25 using formula (6), which does not satisfy S > [S], so increase η and recalculate;

[0106] ⑦ η is taken as 6 for calculation. According to the calculation formula (1)-(3), [R]'=123.66, which satisfies R<[R]', proceed to the next step;

[0107] ⑥ Calculate L0 = 21.955 < 25 using formula (4), which satisfies L0 < [L0], and proceed to the next step;

[0108] ⑦ Calculate S0 = 45.415 > V = 25 using formula (5), which satisfies S0 > [S0]; calculate S = 33.931 > V / 1.2 = 25 using formula (6), which satisfies S > [S];

[0109] ⑧ The dimensions of the wedge-shaped inlet / outlet plane are: R = 50, r = 0.5, L1 = 16.5, L = 10.87, d = 4.5.

[0110] The above description is a detailed description of the preferred embodiments of the present invention. However, the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications made under the technical spirit of the present invention should fall within the patent scope covered by the present invention.

Claims

1. A design method for wedge-shaped entrances and exits in urban road medians, comprising: establishing a model of the wedge-shaped entrance and exit and its mathematical formula based on the analysis of vehicle driving trajectories; determining basic parameters and verifying them based on the mathematical formula, combined with the road's technical indicators and cross-sectional conditions; and finally determining the dimensional parameters of the wedge-shaped entrance and exit that meet the requirements. The method is characterized by... The specific steps are as follows: Step 1: Based on the road technical standards and the standard cross-section layout of the road, determine the main line design speed V0, the side median width D, the distance d1 from the center line of the outermost lane of the main road to the side median, and the distance d2 from the center line of the innermost lane of the auxiliary road to the side median. Step 2: Determine the basic parameters: nose radius r, lane width d, and speed coefficient k; Step 3: Initially determine the chamfer radius R and the inlet / outlet gradient η, substitute them into calculation formulas (1)-(3), and calculate the limit value [R]' of the chamfer radius. If R≮[R]', increase η and recalculate until R<[R]' is satisfied, then proceed to the next step; where calculation formulas (1)-(3) are: In the formula, L1 is the length of the wedge-shaped transition segment; Step 4: Calculate the net width L0 of the wedge-shaped entrance / exit using formula (4). If L0 ≮ [L0], reduce η and substitute it into the calculation, then proceed to step 3 to re-verify R until L0 < [L0] is satisfied, then proceed to the next step. Wherein, [L0] is the limit value of the net width of the wedge-shaped entrance / exit, and formula (4) is: Step 5: Calculate the safe driving distance S0 at the wedge-shaped entrance / exit using formula (5), and calculate the length S of the straight segment of the driving trajectory at the wedge-shaped entrance using formula (6). If S0 > [S0] is not true, increase η and re-enter step 3; if S > [S] is not true, decrease R and re-enter step 3; if both S0 > [S0] and S > [S] are satisfied, then η and R are the values ​​that satisfy the conditions; where [S0] is the limit value of the safe driving distance at the wedge-shaped entrance / exit, and [S] is the limit value of the length of the straight segment of the driving trajectory at the wedge-shaped entrance. Formulas (5) and (6) are: Step 6: Based on η and R determined in Step 5, the basic parameters of the planar dimensions of the wedge-shaped entrance and exit are calculated, namely the length L1 of the wedge transition section and the distance L of the tangent point in the road direction. Combined with the basic parameters r, R and d proposed in Step 2, the structural parameter values ​​of the wedge-shaped entrance and exit are obtained. Among them, the length L1 of the wedge transition section is calculated by formula (1), and the distance L of the tangent point in the road direction is calculated by formula (7). Formula (7) is L=L0-2·(L1-r)(7).

2. The design method for a wedge-shaped entrance / exit in the median strip of an urban road as described in claim 1, characterized in that: In step 2, when determining the speed coefficient k, k is taken as 0.4 to 0.

6.

3. The design method for a wedge-shaped entrance / exit in the median strip of an urban road as described in claim 1, characterized in that: When initially determining the chamfer radius R in step 3, it is necessary to satisfy R > [R], where [R] is the limit value of the chamfer radius.

4. The design method for a wedge-shaped entrance / exit in the median strip of an urban road as described in claim 1, characterized in that: In step 5, [S0] = V, where V is the running speed of the wedge-shaped inlet and outlet, V = k·V0.

5. The design method for a wedge-shaped entrance / exit in the median strip of an urban road as described in claim 1, characterized in that: In step 5, [S] = V / 1.2, where V is the running speed of the wedge-shaped inlet and outlet, V = k·V0.

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