Method for estimating traffic operation efficiency and time economic loss of waterlogged road section

Abstract

The invention discloses a method for estimating traffic operation efficiency and time economic loss of a waterlogged road section. The method comprises the following steps: establishing a waterlogged depth and distance relation model; according to the ponding depth of each point on the road section, calculating free flow vehicle speed and average vehicle speed before and after ponding; calculating passing time before and after ponding to obtain delay time generated by ponding of the road section; and according to the average delay time, the traffic flow, the number of passengers and the unit time value of each type of vehicles, estimating the total time economic loss of the ponding road section in unit time. According to the method, numerical calculation of the driving speed, the passing time and the delay time of the ponding road section can be realized, and a technical support is provided for evaluating the influence of ponding on road traffic operation efficiency and economic loss.

Description

Technical Field

[0001] The invention belongs to the technical field of traffic operation evaluation, and specifically relates to a method for estimating traffic operation efficiency and time economic loss on a flooded road section. Background Art

[0002] Road waterlogging will have many negative impacts on the operation of urban transportation systems. First, waterlogging will slow down the speed of vehicles and increase the travel time of vehicles; second, waterlogging will reduce the traffic capacity of roads, causing traffic congestion and driving delays; third, waterlogging will hinder pedestrians and cause certain damage to vehicles and roads. In severe cases, road waterlogging may paralyze the transportation system and affect the normal travel and daily life of citizens. Therefore, estimating the traffic operation efficiency and time economic loss of flooded sections has important research value and practical significance.

[0003] When roads are flooded, the speed of vehicles will be affected by factors such as road waterlogging, traffic density, and traffic flow. There is little research on how to establish a mapping relationship between the speed of vehicles at each point on the flooded road section and the depth of waterlogging, calculate the average delay of the section based on the waterlogging depth and the speed of vehicles, and estimate the time and economic losses. It is difficult to provide corresponding technical support for emergency decision-making and intelligent traffic control strategies in cases of road flooding. Summary of the invention

[0004] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, to provide a method for estimating the traffic operation efficiency and time economic losses of flooded sections of road, to realize the numerical calculation of the driving speed, travel time and delay time of flooded sections of road, and to provide technical support for evaluating the impact of waterlogging on road traffic operation efficiency and economic losses.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for estimating traffic operation efficiency and time economic loss of a flooded road section, comprising the following steps:

[0007] Establishing a waterlogging depth and distance relationship model, and obtaining the waterlogging depth at each point on the road section based on the waterlogging depth and distance relationship model;

[0008] According to the depth of water at each point on the road section, the free flow speed and average speed before and after the water accumulation are calculated;

[0009] Calculate the travel time before and after the waterlogging to obtain the delay time caused by the waterlogging on the road section;

[0010] Based on the average delay time, traffic flow, number of passengers and unit time value of each type of vehicle, the total economic loss per unit time of the flooded road section is estimated.

[0011] As a preferred technical solution, the establishment of a water accumulation depth and distance relationship model is specifically as follows:

[0012] Based on the water depth detection data, determine the relationship between the water depth x at each point on the road section and the distance l from the point to the starting point of the flooded section:

[0013] x=f(l)(0≤l≤L)

[0014] In the formula, the unit of x is cm, the unit of l is km, f represents the functional relationship of the water depth at the waterlogged location, and L represents the length of the flooded section in km.

[0015] As a preferred technical solution, the free flow speed and average speed before and after the waterlogging are calculated according to the waterlogging depth at each point on the road section, specifically:

[0016] The congestion density of the known road section is ρ j , the unit is pcu / km, the free flow speed when there is no water is v f , in km / h, using the Greenshields flow-density-speed model to calculate the average vehicle speed v q :

[0017]

[0018] In the formula, v q It represents the average vehicle speed when there is no water accumulation and the traffic flow is q, in km / h, q represents the average traffic flow, in pcu / h;

[0019] Using the "hyperbolic tangent function", calculate the free flow speed v at the point where the water depth is x fx :

[0020]

[0021] In the formula, v fx The unit is km / h, a represents the median value of the critical water depth for vehicle stagnation, in cm, and b is the attenuation elastic coefficient;

[0022] The free flow speed v corresponding to the water depth x fx , using the Greenshields flow-density-speed model to calculate the average vehicle speed v q,l :

[0023]

[0024] In the formula, v q,l It represents the average vehicle speed when the distance from the starting point of the flooded road section is l and the traffic flow is q, in km / h.

[0025] As a preferred technical solution, the travel time before and after the waterlogging is calculated to obtain the delay time caused by the waterlogging on the road section, specifically:

[0026] According to the length L of the flooded road section and the average vehicle speed v q , calculate the travel time t of the road section before the waterlogging, in h:

[0027]

[0028] According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after waterlogging P , in h:

[0029]

[0030] Calculate the delay time d caused by waterlogging on the road section, in hours:

[0031] d=t P -t.

[0032] As a preferred technical solution, the total economic loss per unit time of the flooded road section is estimated based on the average delay time, traffic flow, number of passengers, and unit time value of each type of vehicle, specifically:

[0033] Based on the average delay time, traffic volume, number of passengers, and unit time value of each type of vehicle, the estimate is:

[0034]

[0035] Where, L t It represents the total economic loss per unit time of the flooded road section, in RMB / h, n represents the number of vehicle types, d i represents the average delay time of vehicle type i, in h, q i represents the average traffic flow of vehicle type i, in pcu / h, m i represents the average number of passengers of vehicle type i, in persons / pcu, V i It represents the average value per passenger per unit time of vehicle type i, in Yuan / person / h, obtained from local economic data.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] 1. The present invention takes into account the impact of road waterlogging and flow on driving speed. By establishing a model for the relationship between road waterlogging depth and distance, using a model for the relationship between waterlogging depth and free-flow speed and the Greenshields flow-density-speed model, a method for calculating the average driving speed of vehicles on flooded road sections is provided.

[0038] 2. The present invention provides a method for calculating the travel time and delay time of a road section under the condition of road flooding. By using the water depth-position relationship model, the numerical calculation of the driving speed, travel time and delay time of any flooded road section can be realized.

[0039] 3. The present invention provides a method for quantitatively calculating the traffic operation efficiency and time economic losses of flooded sections, which can take into account factors such as traffic flow, number of passengers, and value per unit time, and estimate the total time economic losses per unit time of flooded sections, providing technical support for traffic management and emergency response. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A flow chart of a method for estimating traffic operation efficiency and time economic loss on a flooded road section according to an embodiment of the present invention;

[0042] Figure 2 A graph showing the relationship between water depth and distance at each point on a road section according to an embodiment of the present invention;

[0043] Figure 3 is a graph showing the relationship between water depth and free flow speed according to an embodiment of the present invention;

[0044] Figure 4 Graph showing average speed at each point on a road section according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0046] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application may be combined with other embodiments.

[0047] The embodiment selects a road section with a total length of 0.25 km as an example. It is known that the speed limit of this road section is 60 km / h and the traffic flow of a single lane in one direction is 400 pcu / h. Figure 1 A method for estimating the traffic operation efficiency and time economic loss of a flooded road section is shown, and the calculation is as follows:

[0048] Step S1: establishing a waterlogging depth and distance relationship model, and obtaining the waterlogging depth of each point on the road section based on the waterlogging depth and distance relationship model.

[0049] Furthermore, step S1 is specifically as follows:

[0050] Based on the water depth detection data, the relationship between the water depth x (cm) at each point on the road section and the distance l (km) from the point to the starting point of the flooded road section is determined as follows:

[0051] x=-1056l 2 +264l (0≤l≤L) (1)

[0052] In the formula, L represents the length of the flooded road section (km). Here, the relationship between the depth of water and the distance at each point on the road section is as follows: Figure 2 shown.

[0053] Step S2: Calculate the free flow speed and average speed before and after the water accumulation according to the water accumulation depth at each point on the road section.

[0054] Furthermore, step S2 is specifically as follows:

[0055] The congestion density of the known road section is ρ j (pcu / km), the free flow speed when there is no water is v f (km / h), using the Greenshields flow-density-speed model to calculate the average vehicle speed v q :

[0056]

[0057] In the formula, v q represents the average vehicle speed (km / h) when there is no water accumulation and the traffic flow is q, and q represents the average traffic flow (pcu / h). Here, according to the characteristics of the road section, the congestion density ρ is known j Take 150pcu / km, free flow speed v f Take 60km / h, single lane traffic flow is 400pcu / h, after calculation v q It is 57.2km / h.

[0058] Use Figure 3The "hyperbolic tangent function" shown in the figure calculates the free flow speed v at a point with a water depth of x. fx (km / h):

[0059]

[0060] In the formula, a represents the median value of the critical water depth of the vehicle stagnation (cm), and b is the attenuation elastic coefficient. Here, according to relevant domestic data, a is taken as 15 and b is taken as 6.

[0061] The free flow speed v corresponding to the water depth x fx , using the Greenshields flow-density-speed model to calculate the average vehicle speed v q,l :

[0062]

[0063] In the formula, v q,l represents the average vehicle speed (km / h) when the distance from the starting point of the flooded road section is l and the traffic flow is q. The average speed curve of each point after the flooding is drawn as follows Figure 4 shown.

[0064] Step S3: Calculate the travel time before and after the waterlogging to obtain the delay time caused by the waterlogging on the road section.

[0065] Furthermore, step S3 is specifically as follows:

[0066] According to the length L of the flooded road section and the average vehicle speed v q , calculate the road section travel time t(h) before the waterlogging:

[0067]

[0068] Here, t is calculated to be 0.0044h, or 15.73s.

[0069] According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after waterlogging P (h):

[0070]

[0071] Here, it is calculated that t P It is 0.0074h, or 26.80s.

[0072] Calculate the delay time d(h) caused by waterlogging on the road section:

[0073] d=t P -t (7)

[0074] Here, d is calculated to be 0.0031h, or 11.06s.

[0075] Step S4: Estimate the total economic loss per unit time L of the flooded road section based on the average delay time, traffic flow, number of passengers, and unit time value of each type of vehicle t (Yuan / h) is:

[0076]

[0077] In the formula, n represents the number of vehicle types, d i represents the average delay time (h) of vehicle type i, q i represents the average traffic flow of vehicle type i (pcu / h), m i represents the average number of passengers of vehicle type i (person / pcu), V i It represents the average value per passenger per unit time of vehicle type i (yuan / person / h), which can be obtained from local economic data.

[0078] Here, only ordinary passenger cars are considered. According to the passenger car traffic flow of 400pcu / h, the average number of passengers is 3, and the local average hourly time value per person is 55 yuan, it can be calculated that the economic loss of time per lane of this section due to road waterlogging is 202.8 yuan per hour.

[0079] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0080] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for estimating traffic operation efficiency and time economic loss in flooded road sections, characterized in that: The following steps are involved: Establishing a waterlogging depth and distance relationship model, and obtaining the waterlogging depth at each point on the road section based on the waterlogging depth and distance relationship model; According to the depth of water at each point on the road section, the free flow speed and average speed before and after the water accumulation are calculated; Calculate the travel time before and after the waterlogging to obtain the delay time caused by the waterlogging on the road section; Based on the average delay time, traffic flow, number of passengers and unit time value of each type of vehicle, the total economic loss per unit time of the flooded road section is estimated.

2. A method for estimating traffic operation efficiency and time economic loss in a flooded road section according to claim 1, characterized in that: The establishment of the water accumulation depth and distance relationship model is specifically as follows: Based on the water depth detection data, determine the relationship between the water depth x at each point on the road section and the distance l from the point to the starting point of the flooded section: x=f(l)(0≤l≤L) In the formula, the unit of x is cm, the unit of l is km, f represents the functional relationship of the water depth at the waterlogged location, and L represents the length of the flooded section in km.

3. The method for estimating traffic operation efficiency and time economic loss of flooded road section according to claim 1 is characterized in that: The free flow speed and average speed before and after the waterlogging are calculated according to the waterlogging depth at each point on the road section, specifically: The congestion density of the known road section is ρ j , the unit is pcu / km, the free flow speed when there is no water is v f , in km / h, using the Greenshields flow-density-speed model to calculate the average vehicle speed v q : In the formula, v q It represents the average vehicle speed when there is no water accumulation and the traffic flow is q, in km / h, q represents the average traffic flow, in pcu / h; Using the "hyperbolic tangent function", calculate the free flow speed v at the point where the water depth is x fx : In the formula, v fx The unit is km / h, a represents the median value of the critical water depth for vehicle stagnation, in cm, and b is the attenuation elastic coefficient; The free flow speed v corresponding to the water depth x fx , using the Greenshields flow-density-speed model to calculate the average vehicle speed v q,l : In the formula, v q,l It represents the average vehicle speed when the distance from the starting point of the flooded road section is l and the traffic flow is q, in km / h.

4. The method for estimating traffic operation efficiency and time economic loss of flooded road section according to claim 1 is characterized in that: The travel time before and after the waterlogging is calculated to obtain the delay time caused by the waterlogging on the road section, specifically: According to the length L of the flooded road section and the average vehicle speed v q , calculate the travel time t of the road section before the waterlogging, in h: According to the average vehicle speed v after the water accumulation q,l , calculate the travel time t of the road section after waterlogging P , in h: Calculate the delay time d caused by waterlogging on the road section, in hours: d=t P -t。 5. The method for estimating traffic operation efficiency and time economic loss of flooded road section according to claim 1 is characterized in that: The total economic loss per unit time of the flooded road section is estimated based on the average delay time, traffic flow, number of passengers, and unit time value of each type of vehicle, specifically: Based on the average delay time, traffic volume, number of passengers, and unit time value of each type of vehicle, the estimate is: Where, L t It represents the total economic loss per unit time of the flooded road section, in yuan / h, n represents the number of vehicle types, d i represents the average delay time of vehicle type i, in h, q i represents the average traffic flow of vehicle type i, in pcu / h, m i represents the average number of passengers of vehicle type i, in persons / pcu, V i It represents the average value per passenger per unit time of vehicle type i, in Yuan / person / h, obtained from local economic data.

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